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IDE RAID Examined
Bender writes "The Tech Report has an interesting article comparing IDE RAID controllers from four of the top manufacturers. The article serves as more than just a straight product comparison, because the author has included tests for different RAID levels and different numbers of drives, plus a comprehensive series of benchmarks intended to isolate the performance quirks of each RAID controller card at each RAID level. The results raise questions about whether IDE RAID can really take the place of a more expensive SCSI storage subsystem in workstation or small-scale server environments. Worthwhile reading for the curious sysadmin." I personally would love to hear any ide-raid stories that slashdotters might have.
IDE can only handle one or two hard drives per channel, which makes the cabling a real nasty hassle as opposed to SCSI-based RAID.
Even those so-called rounded cables can clutter the hell out of a tower case if you have a 4-channel RAID controller.
In my case it's the Adaptec 2400A four-channel, with four 120GB Western Digital hard drives, RAID 1+0.
Whats the point in having SCSI-Raid in most workstations these days? I mean, ram is so cheap now you can throw in a couple gigs for much less then the price diffrence between SCSI RAID and IDE raid.
I mean, I know the hest drives are SCSI flavor, but it seems like there's so many other things you could spend money on first that would get you way better performance, like getting a Dual Athlon CPU or something.
autopr0n is like, down and stuff.
At the company I work for, IDE RAID has become somewhat standard because we're basically cheap... At least it's standard on the servers that are fast enough to support it. The rest use dd to copy partitions between backup drives. My boss calls it "RAID point five" We lovingly refer to it as the ghetto network.
I ran an IDE RAID, one of the first, a few years ago. It was a 3ware RAID-1 controller. I thought it would be useful because I had gotten sick of losing data on a drive failure. I didn't have the money (or patience :) for a good backup solution and Linux RAID hadn't matured.
... never have I seen 2 drives go down simultaneously. Nor have I seen a controller malfunction in a way that damaged the drives (though I've heard of it from other people).
Everything was fine for awhile. After a few months I lost a drive, replaced a drive and it remirrored fine. Same thing happened a year or so later.
Then one day my controller fried. Nothing else in the system went down, but some kind of surge hit the 2 drives from the RAID controller. The controller still worked but neither drive was accessible, either as RAID drives or as single drives. Tried numerous tricks, eventually gave up.
I've run SCSI RAID in boxes I admin at work
All in all, I decided it wasn't worth it. I am currently doing Linux mirroring in combination with journaling filesystems on one box, and Windows mirroring on another.
It is more productive to voice thoughtful opinions (reply) than to judge (moderate) others.
---- El diablo esta en mis pantalones! Mire, mire!
I've got a RAID-5 machine made with 5200 RPM WD 120 GB drives. Works great. It's a light server, and I built the thing for under 700 bucks, dual procs and all.
I didn't use a RAID card, just a couple of IDE cards. And it was amazingly simple to set up.
Linux - Because Mommy taught me to Share.
I personally would love to hear any ide-raid stories that slashdotters might have.
Once upon a time, in an array far, far away, there lived a young princess who was worried about the integrity of her data...
My favourite quote from the article : As an added bonus, the lights sometimes flash in a side-to-side in a pattern reminiscent of Knight Rider's KITT.
I'd be happy if I could find a decent external IDE RAID enclosure at a good price. So far, the only ones I've seen cost waaaaaaaaay too much money. Is there anything similar to a Sun 711 Multipack for IDE? (Hopefully something I can buy on the cheap through Ebay?)
I don't quite understand where this Inexpensive crap came from. RAID was around long before IDE RAID controllers started showing up and of course SCSI RAID arrays almost always use very expesive disks. It's Redunant Array of Independent Disks, always has always will be.
You would think that after 130 graphs comparing the controllers he could come up with a stronger conclusion than "I cant really decide which one is the best"
"The defense of freedom requires the advance of freedom" - George W Bush
I work in a 24x7 shop and we've been using the 3Ware Escalade series as well (using Slackware here). They're really nice: the drivers are in the kernel - none of this add a binary driver that might or might not work with later kernel updates stuff. Painting oneself into a corner is for the birds.
A friend of mine set up a raid0 (striped array) using the built-in raid-controller in his motherboard. Later, this motherboard had to be changed. To our great surprise, the raid information was only stored in the motherboard and thus permanently lost. This could be a good thing to know ... Make sure the data is not lost if the controller fails.
Personnally, I run several software RAID arrays under Linux and it works very well. It's easy to manage and gives me decent performance on my rather old machine.
I feel very confident in mirroring system/boot partitions on my linux machines =)
My experiences with IDE RAID have been pretty darn good. Benchmarking my Desktar 60GXP drives in Windows 2000 last year showed that I was getting read speeds in striping mode (between two drives) at faster rates than the fastest seagate Cheetah SCSI drives. Times have probably changed now though.
I started with a KT7A-RAID mobo. The important thing is that you get the cluster sizes just right for your particular partition. I used Norton Ghost to image my drive and try all sorts of different variables. In the end I had very satisfying results. Since I switched to Linux, I stopped using RAID-0 (yes, it is supported with this device!). I found that ReiserFS and the multi-drive Linux filesystem on these drives seemed to be just about as fast without having to hassle with soft-RAID controllers. It is probably due to my system RAM though. I couldn't seem to get Windows 2000 to make the most of 1024 MB without using that swapfile. Linux seems to avoid the swap altogether and uses static RAM instead. It is very nice having the extra IDE channels though. Without them, I probably wouldn't have 4 HDs hooked up right now.
I can't remember how I got by without IDE RAID ...
In fact I love IDE RAID so much I reccommend it to everyone I see on the streets ...
I even bought one for everyone in my family, just in time for the hollidays ...
Thank you IDE RAID, THANK YOU!
Ignore the "p2p is theft" trolls, they're just uninformed
True, but both cheep IDE drives and expensive SCSI drives are cheep compared to something like a 7133 Serial Disk System today. And especially cheep compared to "enterprize" storage solutions of yesteryear when RAID was coined.
You are wrong.
The orignal meaning was inexpensive.
When RAID was invented disk size was scaling up more slowly than demand and there was a huge price premium for the largest drives available. Economies of scale meant that smaller drives meant for the PC market were rather cheap, while larger drives remained very expensive. The epiphany of the RAID inventors was that since the price/storage unit was so much lower with smaller drives, it made sense to eschew large drives and stack multiple smaller drives together to achieve the same space with higher performance and lower price.
I bought that about a while ago when the maxtor 160GB 5400RPM drives started to ship.
:) Reminds me when I plugued my first gigabyte drive in my amiga and saw big numbers :)
:).
I had to build a datacenter and storage price was the main issue. I had to have something cheap, yet hold a LOAD of data. Problem is personally I hate maxtor drives, I always found the more or less reliable (but drive experiences varies from a person to another so..). Anyways at that time maxtor were the only one offering 160GB drives, at a decent price/meg, and although 5400RPM is quite slow for access time, the main issue was cost so I could take a hit on access speed as long as "streaming" speed was fast enough.
the Adaptec 2400A card was the best at the time, simple, cheap efficient, it had 3 bad sides for my application, no 48Bits LBA support (130GB+), no 64bits PCI version (I was using a K7 thunder, and that chipset will slow down the pci bus to the slowest card connected to to bus, and since I wanted all available bandwidth to be thrown to the 64bits gigabit card, I couldn't accept using 32bits), and finally, no more than 4 drives. I wanted to break the terrabyte limit, so let's say I would have used 2 of those cards, it wouldn't have been price-performance-wise since the 2 would have shared the bus and I would have lost 2 drives for raid-5 instead of one with a 8 drive setup. but the performance of the Adaptec 2400A was the best. Still looks like the best overall today, yet I dunno if they are supporting 48bits LBA?
Anyways the 3ware 7850 was an excellent choice. Although their tech support is more or less good (like most tech supports) especially for real bugs and not just standard drivers reinstallation issues, the response time and sales people were very nice and professionnal. I got surprising results from the array, where I thought it would run like molasse, I was getting over 50MB/sec sustained non-sequential reading if I recall correctly. And the tools are very good, rebuild time is about 3-4 hours with 8x160GB @ 400GB filled on the drives, there are email alert tools and web interface to the host machine to check diagnostics. Overall it's a nice system and I'm sure the 7500 series are even better.
Oh and on a "funny" note, windows shows 1.1TB available in the explorer window, not 1134GB
As for the maxtor drives, I didn't take any chances, I ordered 10 to get 2 spares, 2 blew off in less than a month, but didn't have any problems since then, I guess if you can afford the time, doing a 1 month burn-in test with non critical data isn't overkill. usually they SHOULD blow up one by one so you could rebuild the array
--- Metamoderating abusive downgraders since my 300th post.
Thats bullshit. Post some links to benches that back that up.
Two 80GB WD special edition drives in RAID 0 (7200RPM, 8mb cache) rarely burst over 90MB/s. They usually have a sustained transfer of ~50-65MB/s.
Additionally, your seek time is going to suck. I gaurantee its not going to be under 11ms. You cpu utilization during transfer will prolly be around 4% in the asolute best case senario and 11% on average. This is becuase, no matter what you think, all raid cards under ~140$ do the calculations for the transfers in software, not hardware. All you have is a controller card with special drivers. You wont come even close to beating the overall performance of a scsi 160 drive, or SCSI 160 RAID 0 setup.
HP has developped a pretty cool type of RAID. An automatic RAID-level that automatically organizes your disks for best performance while maintaining security.
When a friend explained it to me, it sounded like a mixture of raid 5 and 0+1. For example, if you replace a disk with a larger one, the extra capacity will be used to duplicate some other part of the array.
White papers here
We've run several big RAID-5 setups on 3ware cards. When I say big I mean 1TB+ on each card. To do this we've used the 100GB+ drives available (120GB - 160GB) The biggest problem has been drive failures. Out of the 40 drives I think we've lost 6 in less than 1 year. In only 1 case have 2 drives gone bad at once (RAID-5, we're covered if 1 drive fails), but lost around 1TB of data. Luckily the data could be reproduced but took two weeks to regenerate.
It's WAY too easy to build massive arrays using these devices. How the hell are you supposed to back them up? You almost have to have 2, one live array and 1 hot spare array. If you think you're going to put 1TB on tape, forget about it. If you have the cash to buy tape technology with that capacity and the speed to be worthwhile, you should be buying SCSI disks and a SCSI RAID controller.
Using IDE Raid is like using a winmodem. Unlike with modems, where everyone has one, RAID has a basic educational entry point. I seriously doubt IDE Raid will ever overtake SCSI in any area where knowledgeable people are doing the administration.
I have about 5 TBs of RAID5 storage online at various customer sites. They are all using Linux software RAID and Promise ATA66/100/133 controllers. Even when using two drives per IDE channel, we still see very good performance. An RAID5 system with eight 120-GB 5400-RPM Maxtor drives gives about 55 MB/sec write and 80 MB/sec read performance under Bonnie. Those eight drives were on two Promise ATA100 controllers. Cabling is fairly easy if you use 24" UltraATA cables. And it will get much easier with Serial ATA.
One customer ordered a system from a vendor who insisted on installing an ATA raid card, and it was a remarkable disappointment. Linux was able to indentify the array as a SCSI device and mount it. Then, for some reason, the customer rebooted his system. During the BIOS detection, the raid card started doing parity reconstruction and ran for over 24 hours before finally allowing the system to boot! For comparison, the same sized array would resync in the background under Linux in about 3 hours.
Also, the reconstruction tools built into the raid cards are pretty limited. If you have a problem with a Linux software RAID array, at least you can use the normal low level tools to access the drives and try to diagnose the problems. Just MO.
Yep, seconded. 3Ware have been good in my experience. Nice mgmt software also.
I've used software RAID1 in linux for a couple of years and while it does work, it can be tricky sorting out bootloader issues. I've settled on 3ware for IDE RAID from now on.
SCSI is nice, but IDE has better bang for the buck.
No, I did not read the f***ing article!
Here's a mod I posted before that converts a cheap Promise ATA-100/133 or ATA-66 controller into a RAID unit. http://www.tweakhardware.com/guide/raid100/ The last time I checked, Maxtor was selling the Promise unit as their own brand as well. This means that it's in wide distribution.
RAID 5 can be a pretty poor performer, even with a dedicated RAID card with processor and cache memory.
(writes in particular)
I can't imagine doing software RAID 5, as the overhead is quite high.
Promise controllers have a quirky setup display. About two years ago they said they would fix it, but haven't done that.
Anyone have comments about the others?
Is this a troll? You're bitching because your el cheapo HighPoint RAID controller (software RAID, I might add) isn't up to running a production mail server?
In any case, we use software RAID-1 so that the system can survive a drive crash. We started using RAID-1 on SCSI with the AIX Logical Volume Manager, and began using Linux RAID-1 on IDE when the Promise PCI controllers were supported in RH72.
We have lots of AIX and Linux systems, and have had a dozen drive crashes over the years.
I don't quite understand where this Inexpensive crap came from. RAID was around long before IDE RAID controllers started showing up and of course SCSI RAID arrays almost always use very expesive disks. It's Redunant Array of Independent Disks, always has always will be.
It probably comes from the original reseach paper... A case for redundant arrays of inexpensive disks in the Proceedings of SIGMOD International Conference on Data Management, 1988. (Pages 109-116.) SCSI drives were an inexpensive option compared to other storage technologies that offered high performance and fail over safety.
Over time the acronym expansion was changed to become "redundant array of independent disks" as RAID become more popular (and affordable) for smaller systems.
Some references: here, here and here
Having made the investment, I'll be wringing every last drop of sweat out of my homebuilt Linux/SCSI-160 network attached storage array thank you very much! I'm hoping that by the time that is on its last legs I'll be able to drop in a SerialATA RAID controller and a whole bunch of cheap drives to build the multi-terabyte storage array everyone will inevitably want by then.
UNIX? They're not even circumcised! Savages!
Holy cow. Sistina LVM (Logical Volume Manager) rocks. It is a partition system/file system of the future that really makes RAID sort of unnecessary. It is true that it is done by the host OS, but when integrated right it does not matter.
Documentation for LVM is great. It is stable and works without quirks. It does all of the things that I would typically desire from a RAID 0,1,5 setup. Administration tools are awesome and give output just as I hoped. Expand partition sizes LIVE (ext2resize needs to unmount though, that is not LVM's problem), move a file system to another physical drive, mirror partitions, spread partitions over various devices. LVM is NUTSO!
It is built into the Linux kernel past 2.4.7 (or somewhere around there), though I have heard that it was inspired from LVM for HPUX. I can't say much about this.
Understanding the concept of how LVM works can be a little hard at first, but once you get past that and then actually use it on a system, you will be totally blown away by what it does and the performance.
Here is the website for LVM
http://www.sistina.com/products_lvm.htm
I personally use Sistina LVM on a Debian Gnu/Linux system that has two IDE 60GB hard disks. I can change the sizes of partitions, move data around, move to a new hard drive on the fly, and tons of things that I don't even think I could do with the highest end of RAID controllers. As for performance, it is software RAID, but it does not have any of the typical software RAID slowness or cruft factor. I initially chose LVM as a cheap alternative to buying an IDE RAID card. Now, I don't even want an IDE RAID controller.
...so be alert.
Each IDE controller can support up to two drives, a master and a slave. What happens if you hang two drives off one controller, and the "master" drive dies?
If it dies badly enough, the "slave" drive can go offline. Now you've got TWO drives in your array that aren't talking. There goes your redundancy.
If your purpose in using RAID is to have a system that can continue operating after a single drive failure, then you better think again before you hang two drives off any one controller.
As it points out in the Linux software RAID docs, you should only have one drive per IDE controller if you're really concerned about uptime. That would imply that "4 channel" RAID cards should only be used with a maximum of two drives, both set to "master", and no "slaves".
Note that this does not apply to SATA drives, as there isn't really a master-slave relationship with SATA -- all drives have separate cables and controller circuits. SATA drives are enumerated the same way as older drives for backwards compatibility with drivers and other software, but they are otherwise independent. (At least that's what I hear, I haven't actually seen one of these beasts yet...)
And of course none of this touches on controller failures, which is another issue. But if you are worried about losing drives and still staying up, then better take this into consideration when you design your dream storage system.
(I don't know about you guys, but I have lost several drives over the years, and not one controller...)
It just means that the first 24 people didn't thorougly read the article.
But this is slashdot. You're not trying to tell me that we're meant to read the articles are you?
I would not suggest it to the average Joe, unless they run Windows...
/. will pay for your controller.
/dev/md0) than it did in Windows98SE/ME/2000/XP. And if anyone HAS used IDE RAID on Windows every last one of the controllers have the same problems. They CAN'T maximize the throughput without the lost of stability & reliability.
I've used IDE RAID since I purchased an Abit KT7-RAID. I've used the HighPoint HPT370 onboard as well as an Adaptec 1200A, the HPT-372/372A and now I'm using a Promise IDE RAID on an MSI KT3 Ultra.
With all the buzz words in this article for the techno geek, shuffle your buttocks to closest place to get one of these bad boys, spend that $100 bucks. If that controller benchmarks better than the SAME IDE DRIVES setup on your normal IDE controller using Linux RIAD..... well
I've went so far as to purchase 4 identical drives (as close as I could for your obssesive perfectionist boneheads). 4 Maxtor 40G ATA-100 7200 RPM drives, put them on the IDE RAID (RAID-0) controller and benchmarked them using SiSoft. Put the same drive on Mandrake 8.2/Redhat 7.3 and it showed higher drive throughput under Linux (using hdparm -Tt
For those who've lose multiple drives in IDE RAID, your victim to another reason IDE will never overtake SCSI in ANY insured business. HEAT. If you can't take the HEAT get the hell outta the real server market.
Those are the facts from someone who USES what the article "tests"
I've nothing of importance to say, now go away before I taunt you with a second sig!
What kind of hardware raid is that?
I'm using IDE raid on my home desktop right now, but I'm using software raid as opposed to a hardware controller. I have two Seagate Barracuda ATA IV 40GB hard drives hooked up as masters to my primary and secondary motherboard IDE ports. I also have a DVD-ROM hooked up as secondary slave, and a Promise Ultra133TX2 controller with a CD-RW hooked up to its first port. Both hard drives are sectioned into a 3GB primary 1st partition and a 34GB (yes, the drives are only 40GB when you're in marketing land) 2nd primary partition. Windows 2000 is installed on the first drive's 3GB partition, and redhat linux 7.3 is installed on the second drive in the same place. Both OSs share the combined 68GB RAID 0 set, which is formatted with NTFS, made from the combined second partitions. The only problem is that linux can't write to the array because NTFS write support under linux is currently "DANGEROUS" according to the driver's author and I keep important data on there. (Yes, I know about the dangers of using RAID0 and I back up regularly.) It'd sure work a whole lot better if that driver were finished, though. (hint hint, Legato Systems, Inc.) ;)
:D After a quick format with NTFS (the partiton was too big to format with FAT32), I was in business.
/dev/md0
/dev/hda2 /dev/hdc2
/etc/raidtab, ran raid0run /dev/md0, and added a line to /etc/fstab. (I read online that WinNT 4.0's software raid driver uses 64K chunks.)
;) As a bonus, I also get to keep my standard partition table as well as compatibility with non-M$ disk editing/management/recovery tools.
Getting the two OSs' software raid drivers to play nicely together was an "adventure", mostly due to Win2K's insistance on turning the disks into "dynamic disks" before letting me use its built-in RAID functionality, meaning it wanted to wipe out my old partition table, replace it with a single partition taking up the entire disk, and create a new system of partition organization inside the dummy standard partition. After a lot of reading, I found out that Windows NT 4.0 supported "stripe sets" using standard partitions, and that Windows 2000, when installed over an old copy of NT4, would support the "legacy" software RAID drive. Windows 2000 would not, however, allow me to create new legacy stripe sets for compatibility with other OSs. Stupid Micro$oft. So all I had to do was fake Win2K into thinking it had been installed over an old copy of NT4 which had been using its stripe set functionality.
The first thing I had to do was create partitions. I opened up linux fdisk and allocated 3GB on each disk to my OSs, one for linux and one for windows, and created two partitions, each one taking up the rest of the space on its disk, and set their types to 87h (NT stripe set [thanks to whoever put the L command in linux fdisk!]). After installing Windows 2000 on the first disk's first partition, I needed to get my hands on a couple of tools that didn't come with windows 2000: Windows NT 4 Disk Administrator and MS's fault tolerant disk set disaster recovery tool, FTEDIT. After spending about 6 hours searching online, I finally found a download site for FTEDIT - MS's web site says you can get it free from them, but it provides no download link. NTDA was a bit easier. Since MS service packs replace OS files, and somewhere in NT4's history a bug or problem had been found in NTDA, that file was in the service pack 6a for NT4. Service packs check to see if you're using the correct OS _after_ they decompress themselves, and they're nice enough to display an error message telling you this ("Whoops. You just wasted a whole bunch of time downloading a huge file you didn't need. Sorry!") before they delete the decompression directory. Figuring that out took a while, but snagging the executable during decompression was easy.
I ran NTDA, which populated the "missing" DISKS key in the windows registry (Win2K stores disk information in a different place from NT4), and told FTEDIT that, yes, I really did already have a software RAID 0 set on those drives, and that windows NT had died on me and I had to restore it. After a reboot, "Drive D" appeared in my computer. 68GB and unformatted. YAY!
Getting linux to see the array was much easier. I added
raiddev
raid-level 0
nr-raid-disks 2
persistent-superblock 0
chunk-size 64
device
raid-disk 0
device
raid-disk 1
to
Btw, yes, I know linux has support for MS's dynamic disk scheme. I enjoy tweaking and doing new things, even if it means days spend reading about Windows.
"So," you're probably wondering, "why did Erpo spend all that time setting up a RAID0 set (presumably for extra performance) and then go and do a stupid thing like put a DVD-ROM drive on the same ata cable as one of the disks when he has an extra ata port on his add-in controller that he's not using?" Thanks for asking. It's because Promise's bios on the Ultra133TX2 card was broken. The company "Promised" me it would allow me to boot from CD, but in reality it only will let me do so when I want to boot from a windows installation CD. Not just any windows installation CD, either. It had to be Windows 2000 Professional or XP, which I refuse to use.
It wouldn't recognize my Windows 98 SE cd, or any of my linux distros. I didn't have a choice about the DVD drive if I wanted to install linux. Just now, months after I got the card and sent promise and email, they released a bios update that claims to fix the issue. If it works I'll be moving my optical drives around. Even with the DVD drive, the performance isn't too bad - about 80MB/sec at the beginning of the disk, and it slowly drops to 50MB/sec at the end.
Promise RAID is actually a software RAID. Don't let the fancy BIOS thiny fool ya. Here's a little story:
:) Those jokers are REALLY SLOW to recompile their kernel modules.
I had a Promise Ultra 100 controller in a system and loaded Linux on it. I tried to get the thing ot run RedHat 7.3. This was back when 7.3 was pretty new... like about 3 months old. I wanted to use the RAID controller since I had nothing else to do with it at the time and I knew Promise was supporting Linux.
Turns out they didn't have a driver for 7.3... just 7.2. I went around and around with them asking them to recompile the driver for me after I was mentioning the merits of oper sourcing drivers and such. Finally I gave up and bought some Maxtor PCI IDE controller out of the CompUSA bargain bin for like $10. It looked familiar...
I pulled the Promise card out and was about to put the Maxtor card in when I realized they were both the SAME DAMNED CARD! It was then I realized the RAID controller depended on software and not some fancy hardware thing. It was then I understood why Promise doesn't want to open source their driver!
Anyway, I put the bargain controller in and used a Linux software RAID. Short end to the story. I got my RAID and it worked. Better end, it was software and I could configure it using Webmin! That probably what you should do. Let the system see the two drives and then do the Linux software RAID... there is a redhat 7,3 driver out on the promise website... but I don't see a redhat 8.0
Here at work our main R&D server's been using a SCSI Mylex960 with RAID1 36GB drives. This has worked dandily for the past several years. This machine gets hit pretty had with tons of small IO, so I wouldn't consider IDE for it.
However, more recently we needed more builds/CDimage space so we picked up a Promise FastTrak100 (TX2) raid controller ($150CA) plus a couple 7200rpm 80GB Maxtors (~$150CA each), and have been living happily ever since. Now for sure we'd never put this in the main server, but for a cheap, reliable solution that gives you tons of space on a server that has only medium load, it can't be beat.
The point is, examine your needs and see what fits!
-Malloc
___________________ I want to be free()!
Our test of the promise raid under redhat linux with the "open source" drivers (2.4.19 vanilla) compared with the 3ware product were VERY different.
I don't have the exact numbers off hand, but the 3 ware product was roughly 3 times faster at reading (raid 0+1 and raid 1). The 3ware was also faster at writing albeit the numbers were much closer. The number that DOES stick in my head was the postmark benchmark from netapp we ran. The promise did 2500 files, from 2 to 200k with 500 operations in about 35 seconds. The 3ware product did the same in 12.
The moral of the story is TEST TEST TEST, these types of articles only give you an idea. Promise worked great for me personally in several applications. After testing it for a production machine at work, we went with the 3ware because the promise did not perform well for our application. Test for youself, or forever be dissapointed.
Cluge
"Science is about ego as much as it is about discovery and truth " - I said it, so sue me.
This "Crap" is because, in ages past, a bunch of smaller drives were WAY cheaper than one large drive.
IT was a way to get large storage space out of small drives, originally. The redundancy issues are there to reduce the failure rate of the array to something matching a single drive (as opposed to say, 20 times as likely if you add 20 drives)
In 1988 SCSI was still bloody cheap compared to, say DASD.
RAID 5 in software can be dangerous. If a parity write fails (disk/system dies), you'll likely have data corruption and not even know it. Best to trust reliable hardware to do the XORs.
Then again, a RAID _card_ may not help here, since the disks are at the mercy of the system power. Best to use a real array, if you have the bucks.
Do you mean it woudn't boot the linux cds at all, or it would boot the kernel and then not mount the root, because the kernel didn't recognize the device[?]
It wouldn't boot the linux cds at all. The card's bios would not detect that the CD was bootable, that is it would totally miss the ElTorito-compatible 2.88MB floppy disk image on the cd if the CD was not a Windows 2000 Professional or XP install disc. Once I moved the DVD drive over onto a motherboard controller, redhat 7.3 installed perfectly. It even loaded linux's pdc202xx driver, detected my CD-RW (which was still on the controller with the buggy bios), and configured ide-scsi emulation so that cd burning would work.
Wow. I'm surprised at all these stories of hard drives going south. I've never had a hard drive die, in many years of use. I still have a badly abused 10 year old 210MB harddrive that still works great. Ditto for the slightly younger, but still badly abused 1GB drive. That said, I don't worry about data loss anymore. Data is far too important to keep on your working machines. Thus, I've got a Linux server where I keep all my data. I've gotten into the habit of putting everything under subversion (it's alpha software, but remarkably stable) so I get everything version controlled for free. Throw in the occasional backup, and not only is my data (all versions of it) acessible anywhere I've got an internet connection, but it should stay accessible in the event that I kill my main machine by abusing it like I do.
A deep unwavering belief is a sure sign you're missing something...
well, if you only had two drives and they were in a raid setup it was either raid 1 or raid 0. if it's raid 0, removing one of them will crash the machine. hard.
if it's raid 1, you can do what ever you want, really.
Everyone say it with me: there are lies, damn lies, and benchmarks.
Free messageboards and more! Your girlfriend's seen myWang
First off, they've failed to note that some of their contestants are in fact just IDE controllers, with the RAID functionality implemented in the software driver (WinRAID, like WinModems), whereas others are Hardware. I don't know all four products well, so I'm unsure on at least one of them as to which are which.
They tested CPU utilization, and seperately various speed tests, but never a comprehensive "loaded system" test. As expected they ranked the Adaptec (a true hardware RAID) lowest, while ranking the WinRAID's higher. This couldn't be further from the real truth. Sure, the idle P4 cpu does a great job of fast software RAID compared to the embedded RAID ASIC on Adaptec's card. However, if you had a heavily loaded server machine, where the processors were loaded down doing other things (say SSL-encrypting for an secure web server), the machine with the Adaptec would trounce the others, as the RAID processing speed will not decrease while your applications are using most of the CPU (or depending on the device driver's pre-emptability, it could be the other way around, that the CPU simply wouldn't be as available to your CPU-hungy SSL server as it's busy with the RAID).
11*43+456^2
The Seagate barracuda IV had a problem when connected in RAID-0; it actually performed worse than as a single drive. There was a problem with caching on them that made RAID controllers gag. There is a firmware fix; you can contact Seagate and they will replace your drives for you! I currently have 5 Barracuda IV drives connected to my highpoint RAID controller (abit at7) but they are running as single; I use the speed advantage of each being on their own IDE channel.
If you're using Kernel 2.4.19 or later, it's got built-in 20276 support. I've got a GA-7DXR+ and I can use the Promise RAID just fine with my Debian setup.
I just ran modconf to load the appropriate module.
Look, I got modded down! And I didn't even say 'IN SOVIET RUSSA...'
Here's the thing with raid 0.
You no longer have one single point of failure for your data, you have 3 single points of failure: the card (which, it has been noted in the thread, stores the config info internally) and each drive. The failure of any one of these three components wipes out ALL your data.
If you take the two drives and use them as seperate volumes, you'll still retain the data on the drive that didn't fail.
You SHOULD gain a read performance benefit from a raid 0 config. Which makes it a more palatable solution for an application where you are keeping a seperate copy of data somewhere else (such as a web server in a farm that serves mostly static content.
We ended up going with the Promise UltraTrak SX8000, which is an external RAID cabinet that holds up to 8 IDE drives and connects up to the host computer via SCSI. We then got 8 120GB Western Digital drives for around 150$ each. The RAID set up quickly, and within an hour we had a formatted 7-drive RAID 5 array with a hotspare for if things went badly.
The cabinet has, in the 4 months since installation, given us zero problems, and worked flawlessly, with quick transfer rates, and extremely easy setup. Considering the price compared to an equivalent SCSI system, we feel that we got 90% of the value of a SCSI system (the only difference being that IDE drives break sooner than SCSI drives, and that SCSI drives are moderately faster, both of which weren't quite necessary for us.)
If your system contains mission-critical data, go the more expensive route and get a full SCSI raid system with multiple hotspares and pay a guy to sit in a corner and maintain it. If, like us, you just need a large amount of very-reliable storage without much hassle, go the IDE RAID route. It's working great for us.
Me too. I walked out on a limb and chose an 8-port Escalade (in 0+1) instead of spending more on SCSI.
I did have a week from hell when the disk system became unstable. I'm pretty sure now that cabling was the problem. 3Ware provided EXCELLENT support.
I've got 5 servers (one is an Exchange 2000 server) at a school with about 200 users. All servers are running some form of promise ATA raid 1 setup for boot drives and some also use an ATA raid 1 for their data drives. The file server and mail server use Adaptec 2400A raid controllers with four 100GB drives in a RAID 5 configuration. All hard drives are western digital 7200 RPM drives.
No one complains about speed issues. Everything seems to work very well.....at a fraction of the cost of SCSI.
I love the look on visitors' faces when they see our servers have 300-600GB of available storage...for very little cost. (Backing up all that data still requires SCSI tape arrays...not cheap.)
I've had a couple of drives tank on me here and there, but no data loss yet...just replaced the failed drive...rebooted and in about 20 minutes the array was completely rebuilt.
I am a fan of SCSI (got plenty of SCSI raid at my house) but when you've got to stay under a budget, you can't beat ATA raid.
-ted
The RM8000 from Promise is excellent for read performance, and a joy to manage. It's cheap, and has an Ultra160 interface, and can be managed either from the LCD menu on the front panel, or from a serial port on the back.
There is one caveat, though: I build one to use for a predominantly archive server (so used RAID 5). While Bonnie and solaris iostat confirm excellent read perfmance, with throughput limited by the host's ability to process data, the write performance is lousy (Bonnie shows 100MB/s+ for reads with the V120 pegged at 100% CPU; but write is only 10-20 MB/s).
From the Slashdot story: "I personally would love to hear any ide-raid stories that slashdotters might have." I also would like to hear about this.
Here's my story: I have extensive experience with Promise controllers. An IDE mirror makes data reads faster. If you are about to do a possibly damaging operation, it is good to break the mirror, pull out one of the hard drives, and do the operation on the other drive only. Then, when craziness happens, the other drive is a complete backup.
A mirroring controller is a convenient way to make a Windows XP operating system hard drive clone. Windows XP prevents this; normally third-party software that runs under DOS is needed to make a useable full hard drive backup. See the section "Backup Problems: Windows XP cannot copy some of its own files" in the article Windows XP Shows the Direction Microsoft is Going. (The article was updated today. To all those who have read the article, sorry for the previously poor wording of the section "Hidden Connections". Expect further improvements later in this section later.)
But Promise controllers are quirky. Sometimes things go wrong, and there is no explanation available from Promise. Promise tech support is surprisingly ignorant of the issues. The setup is quirky; it is difficult to train a non-technical person to deal with the controller's interface.
Mirrors are a GREAT idea, but Promise is un-promising. That's my opinion. I'm looking for another supplier, so I want to hear other's stories.
WTF is it with people thinking RAID 0 is a good idea? You have my sympathy, but who/what made you think it was a good idea?
True, but you'd also think that after 130 graphs and countless pages of whining about how the RocketRaid 133 had only two controllers he would've realized that the Highpoint 404 would've been a more appropriate choice for this benchmark!
(Still and all, the "404" is a lousy name for anything that's intended to make sure your data can always be found)
Am I the only one who heard Roxette to sing "I'm gonna get blitzed for some sex"?
> I don't quite understand where this Inexpensive crap came from.
RAID (Random Array of Inexpensive Disks) was as opposed to SLED
(Single Large Expensive Disk). (The term "Random" means the same
as in RAM -- i.e., that you can access any part (any drive, in this
case) at any time.)
> RAID was around long before IDE RAID controllers started showing
> up and of course SCSI RAID arrays almost always use very expesive
> disks.
"expensive" is relative. (Instead of thinking of SCSI as the only
other option besides RAID, try to remember that there were larger
and more expensive disks at one time.)
> It's Redunant Array of Independent Disks, always has always
> will be.
It's not necessarily "redundant" at all; some RAIDs are done just
for performance reasons, with no redundancy. (Personally, I am
more interested in the redundancy, however.)
Cut that out, or I will ship you to Norilsk in a box.
I've passed this feedback onto the author of the ide raid-roundup - i figured i might as well post it here too.
I just thought i'd share some of my experiences with promise support.
Frankly, they have been terrible. I would not voluntarily buy another promise product again at this stage based on my experience with them.
I have been attempting to get support for the Promise FastTrack which is a popular embedded raid controller option, under Linux.
Promise indeed "support" RedHat but do so with a binary only, closed source module that in the end turns out to be useless.
Promise hard code a supported kernel version for this driver such that you can run it under say RedHat 7.3, but only the initial 2.4.18-3 kernel, which has a number of critical bugs which have been addressed in later (errata) kernel updates.
Needless to say, promise's driver will not run on any later kernel or at least they are unwilling to answer questions on how to do this.
A comparable analogy would be if they had released Windows XP drivers and then your hard drive failed to work if you installed a hot fix or a service pack because the driver is keyed to only the specific intial installed released of XP. Promise don't treat windows users this way, so why do they do this for linux users ?
I've managed to get two responses out of their support, none of which will address my problem - support the hardware under linux by releasing the source or provide updated kernel drivers for the released kernel images that will actually work.
In terms of driver support for Linux/FreeBSD, 3ware wins hands down in this group.
regards,
-jason
No kidding. Especially with a cost-capacity ratio. On SCSI, to get anywhere near the large amount of IDE capacity, you need multiple drives. And of course, drives in SCSI are not cheap by any stretch of the imagination.
I'd rather shell out for a few 80/120GB drives than be nickel&dimes by a lot of smaller ones, although in the case of SCSI it's more like quarter-and-loonied (dollared for you Americans)
I just saw this:
I'm getting one for my house with 200GB drives....they also make an 8 drive version....mmm....
-ted
Windows 2000 Advanced server on a 486? Are you one of those guys that enjoys pain?
Seriously...if you want the PR 233 and the AT motherboard (with AGP...maybe even 64 or 128 MB memory), reply to this and we'll figure out the shipping address thing. I can't let you suffer like this man!
-ted
HERE
Incidentally you will get both a read and a write performance benefit from raid0. This can be a real boon when you're doing video capture. Capturing a raw AVI at NTSC DVD resolution is roughly 41,472,000 bytes per second. With a single IDE drive, you simply can't achieve this continuous data rate (at least, I couldn't in my setup with ATA/100 drives). Just to check it out, I set up software RAID0 in Win2k on my two extra drives. Handled the capture with 0 frame loss.
Incidentally, the better solution to this particular problem is the HUFFYUV video codec, which is basically lossless compression at roughly a 3:1 ratio of AVI data. Still not suitable for transmitting, but compressing before writing it to disk means you can capture to a non-raid setup.
I can vouch for the stability and speed of one pre-built IDE-RAID Product. RaidZone OpenNAS They use a special raid controller that allows increased IDE Raid speed, and IDE Hot-Swap capability. This one had a total of 1.2TB (plus hot spare). The project involved a unique (to this project) Application that required a proprietary Database System that could only run on an MS Win2k Server, therefore we didnt fully utilize the sytems capabilities. It served as a file server for images (ranging in size from 60kB to well over 100MB per image) (and as I recall the Image Store is now around 500GB), MS SQL Server, confidential proprietary DB system (indexed images, among other things), and several small services (and the chunky MS GUI). It even has a 900GB native backup system attached. The load ranges. Since we put it into action early 2002 it hasn't missed a beat. I would recommend it highly for most applications, though there does come a time when higher speed drives are needed.
Why hasn't the ArcoIDE solution caught on like wildfire? It provides mirrored disk capability with absolutely no visibility to even the motherboard, much less the OS. I've been running it for years and it's great. Mine is the PCI slot model that simply uses the slot to get power to the card. One IDE cable from the motherboard to the card, two cables to the two hard drives.
And there's all sorts of alarming options -- LED's on the card, LED's on a front panel bezel, audible screech, Form C contacts for you industry types ...
I don't get it.
One simple rule for its versus it's
actually, you could solder a resistor on to the promise ultra66 cards and flash it with the fasttrack 66 bios and it worked exactly like the fasttrack.
Of course it was still a shitty card.
-Chris
--an unbreakable toy is useful for breaking other toys--
It looks like these particular adapters take their power independently of the drive so you have to squeeze a power splitter into the drive container.
See my journal, I write things there
Wouldn't your (raid 3) array performance be bounded by the overhead of parity calculation? Wouldn't the write performance be made worse by restricting all parity writes to one hard drive? It seems by distributing parity among all drives raid 5 still carries the parity calculation overhead, but is faster at writing the parity simultaneously to all drives. Am I just splitting hairs here?
-ted
So I was surprised reading the review to see the Adaptec and 3Ware neck and neck in the RAID 5 area. 3Ware's usually have no competition in RAID-5 since their firmware and HW rock.
Then I found out WHY they were so close:
The 3Ware cards are 64-bit cards while the Adaptec's are only 32-bit. 3Ware cards can hit 70MB/sec writing and over 150MBsec reading with 8HD's! If they ever get to 66MHz, I expect their performance to go even higher.
If you want to see better benchmarks that fit with reality, check out the XBit Labs Review
Top Most Bizarre/Disturbing Error Messages
Utilizing eBay and a few vendors that I dug around for, I was able to assemble a blazingly fast fibre channel RAID system for home for around $500. If you take a look at http://www.nuxx.net/gallery/fibrechannel you can see the assembly of the box. There are also benchmarks detailing the RAID 5 array bursting to >160MB/sec (image at http://www.nuxx.net/gallery/fc_benchmarks/aad).
The box is set up as follows:
o Mylex eXtremeRAID 3000 ($200 via eBay)
o Crucial 256MB DIMM for Cache (~$50 from Crucial)
o 4 x Seagate ST39102FC 9GB 10,000 RPM drives ($9/ea on eBay)
o Venus-brand 4-disk external enclosure (~$35 on eBay)
o Custom made FC-AL backplane for disks (~$200 from a site I can't remember at this time)
o 35m FC-AL cable (HSSDCDB9) (~$40 for two on eBay)
The best part? The box is located in my basement, so I have this incredibly fast disk disk access, with no noise and no extra heat inside my case. That also allows me to cool the case more efficiently. Sure, IDE RAID may be cheaper, but the performance, per-disk, coupled with the reduced noise in my office and the reduced heat in the case is a big plus. Also, I might eventually pick up a second backplane for another four disks and do RAID 0+1. Since each channel is capable of 100MB/sec (without caching), the use of a set created across two channels would be amazing.
One correction: the computer sees it as as many SCSI disks as you feel like configuring if the IDE RAID unit is any good; this is certainly the case with Promise equipment).
Thus you could use an RM8000 to provide, say, a 2 disc mirror for a boot volume and a 6 disc RAID 5 for data.
I saw the LVM stuff, and was going to use it on a new install with two 80GB drives (and a separate boot/OS drive). But I wasn't sure about redundancy. How does it handle that? I mean, can I use a "RAID1-esque" pairing with it? Does it do that already? From what I saw, the LVM stuff is really just a move away from BIOS partitions (and terribly cool for those times when /usr/local starts to run low). I'm looking for data security through redundancy, but like the features LVM has.
The machine I'm talking about is a samba/NFS fileserver on a 100mbit (full-duplex, switched) LAN, so I'm not all that concerned about speed as much as I am about recoverability -- as long as disk reads and writes are faster than what comes in over the network I'm plenty happy. The ability to grow "partitions" would be a wonderful added bonus.
It's certainly interesting stuff...
-B
Ash and Hickory, straight-grained and true, make excellent bludgeons, dandy for the cudgeling of vegetarians.
Thanks.
today is spelling optional day.
Sure, it's a parallel cable. But only one device can communicate with the host at once. It's a lot harder to squeeze 100% of the theoretical bandwidth with 8 slow devices than with 4 fast ones. So the parent's comment was mostly accurate.
THIS THING CAN TURN ON A DIME, MACROSSZERO STYLE ALSO FUCK BETA, ~NYORON
It's software raid because you need a driver. A lot of the operations that would normally be performed on the controller in a real RAID controller are passed off to the CPU.
They're all hooked up to a 3ware Escalade 7500-12 card, RAID5, with a hot spare. Application is storage of large amounts of raw digital images 7-8MB each.
Been going for a few weeks now, no problems, 2.4.19 kernel's built in drivers lights the array right up as sda1.
I would show you more but I'm ssh'd in and the power just went out. The 300VA ups running this box while I'm testing it probably just let its smoke out. Doh.
Anyway I like it. If its not fried.
--------------------------------
Not all who wander, are lost.
At our business we use the 3Ware 7500 with a 3x 120GB (1200JB) Western Digital RAID5 configuration on Linux RedHat 7.2. The machine is a dual P3/1GHz on a SuperMicro 370DER motherboard. We use the machine as our primary file server/compilation box, so data integrity and fast failure resolution is critical.
The cited benchmark page has excellent information (130 graphs!), and it confirms my first hand experiences of everyday use of the 3Ware 7500. The read times in RAID5 are outstanding, but there are sometimes significant delays on file creation. In addition, it seems that IO is single piped, or serialized on writes at times.
Since the 3Ware 7500 is based on an FPGA (Field Programmable Gate Array, (see http://www.xilinx.com/), with LOTS of extra ECC processing power, the problem with writes is not likely to be related to the "CPU", but rather part of the internal IO structure of the card. I hope it is amenable to correction with a microcode upgrade to the FPGA, but it may be related to the memory architecture of the card.
Overall, I'm pretty happy with the controller, especially the ease of installation and rebuild time. I have high confidence in the data integrity, and the price is good. I also recommend the drive cage that 3Ware sells, even though it is expensive at $200, it's well worth it because it fits 3 drives in the space of 2 5 1/4 inch bays, and it is hot swap proven.
I'd like to see a shoot-out between the 3Ware and some SCSI/Fibre Channel RAID 5 configurations!!!
Comments?
---- Luke "To boldly go where no one has gone before..."
I always do..
Was running RedHat, using generic I2O drivers, not the Promise drivers, no big deal, though performance wasn't probably as good as it could have been. My main concern was data integrity, not performance.
So anyway, this system is in my bedroom (which sounds like a busy airport, but i like it) and one night I woke up because it was beeping, which means something no worky. I had noticed a few days earlier that I was getting pauses during reads from the disk, which was unusual -- I was going to put the Promise drivers on and see if that made any difference. But then the beeping came. So go in, system still running fine, shutdown and go into the raid bios. It says it's trying to rebuild, and it's failing, it isn't saying it has a bad disk, and even if it did say that, it couldn't tell me which disk because they didn't think that info would be important when they made the product. So, shut it down and pull out each disk, run WD diags on them. Found that one of the disks, during the sector walks, was pausing every now and then for no good reason. Fine, put the working disks back in with a new disk so the array can rebuild. Array rebuilding.. Array fails during rebuild.. WTF? I tried about a dozen configurations and the thing simply wouldn't rebuild. Well, @#$&*!, I'll just rebuild everything from scratch, so back up the data elsewhere on the network. Boot up (i boot from the raid array, I know bad bad), kernel panic after about 3 minutes (it's still trying to rebuild in the background -- and failing, why the panic though i have no idea, might have been the i2o drivers). Take out the new (blank) drive, no more kernel panic (because no more trying to rebuild). So... copy data to network. Put new OS on (this time Gentoo) on a 4GB hard drive for booting only. Rebuild the raid array (which takes f-o-r-e-v-e-r). Copy data back, install apps, lalala, big pain in the ass.
So, bad disk and bad raid controller IMHO. Should have been able to rebuild. However, I did not lose any data. New system has been up and running now with no further problems. Also, performance seems better when using the actual Promise driver, go figure.
Stupider like a fox! - H.S.
Do you know exactly what the problem is? I've never had a problem with my software raid setup.
Personally, I've used RAID (both SCSI and IDE) for a number of systems - and my current workstation is a P4 1.8Ghz i845 board (made by MSI) with integrated Promise EIDE RAID.
Just a few days ago, my system started randomly freezing up - but only when doing lots of disk access on the C: drive. I've seen this behavior once before, when I first built the system; I had a defective IDE drive that was getting read/write errors. I'm pretty sure I have another drive starting to go out.
This type of behavior is disappointing to me, for a system that's supposed to reduce downtime. IDE drive errors while the drive is still mostly functional (EG. spins up ok and works, other than timing out here and there when doing writes) seem to wreak havock with IDE RAID controllers. It only flags a drive as "down" if it's completely unresponsive.
While I haven't seen a higher-end SCSI RAID array behave in this fashion (freezing the whole machine if a drive temporarily malfunctions), I've had plenty of other reliability issues with them.
For example, we had numerous Dell Poweredge servers using their older PERC II RAID cards - and the controllers all started dying off after a couple years of use. The hard drives could be perfectly fine, but if you lost the controller card - you were down until you got it replaced.
It seems like a really worthwhile RAID array would include dual redundant controllers. Otherwise, the controller is your single point of possible failure.
Most IDE RAID setups seem like a gimmick to me, more than a useful feature. People just like to say they have RAID on their home PC.
I have a somewhat amusing story. Just happened yesterday, as a matter of fact. I've got an integrated Highpoint Raid controller, and an Array (Raid - 0) of 2 WD Special Edition 80GB drives. I've got all my information on the drive (with key information backed up onto an additional 40GB drive -- just in case).
Anyway, I went to use my machine the other morning, after waking up. You know, check the mail, play a little music, so and so and so. Only, when I went to access the Array, where the music is, the machine promply locked. Hard. After a reboot, the Highpoint card simply couldn't detect anything past my primary drive (a 20GB drive, has the OS and backups of drivers) and wouldn't even continue or allow me to boot. Now I'm thinking "Shit. One of the drives is fried." or worse. My room and my case are not exactly the most well ventilated.
I opened it up later that night, and, get this, the cables had been knocked loose. Like, very loose. As in, not attached to the controller. It turned out that everything was fine, except that I was extremely paniced for about half an hour during the day.
BTW, the computer is at the end of what amounts to a secondary bed, under a loft. The cables, I assume, got dislodged when my SO and I were playing around there. The case got kicked a few times.
That's my story. Enjoy.
for my money its IDE raid all the way
---- Put Sig here:
I have three 40gb hard drives and am looking for a similar solution. Basicly, I want 20gb for NTFS (win2k), 20gb for ext3 (linux), and 80gb of shared fat32 (raid0) space.
I'm gonna play around with this over the next few days. If I need info, can I send you an e-mail?
Have you thought about drafting a howto?
I'd rather you do it wrong, than for me to have to do it at all.
But this is probably Adaptec's fault, since they label RAID 1+0 and RAID 0+1 opposite from standard convention.
I connect different power supply lines to each of the mirrors' halves, so that one half of each mirror is powered by one line, and the other half is supplied by another line.
If a power supply fails only partially, it usually does so on one of the peripheral power lines. With the right power supply wiring, and the 2400A set up in RAID 1+0 mode, a power supply failure will not usually result in any lost data, since it will be isolated to one half of each mirror.
Power supplies have been failing on me more often than drives have lately, even when they are used well within their rated limits.
Don't power both drives of a mirror with the same peripheral power cable!!! On many power suppplies, those separate peripheral power connector lines are on separate circuits, which means one may fail while the other doesn't. It's best to spread the chances of failure out as evenly as possible across the RAID.
Two-channel IDE RAID cannot support RAID 1+0, only RAID 0+1. Four IDE channels are necessary for RAID 1+0 to be effective, because if one drive fails in a two-channel configuration, the other drive sharing the same channel can stop working too, especially if the failing drive was the master.
Adaptec also offers open-source drivers for the 2400A, while the article neglects to mention that, and in doing so implies that only 3ware and HighPoint do.
Also, the article's table has read/write speeds of the Promise FastTrak shown backwards (133 vs 100).
Nonethless, the article's comments about the 2400A's slow rebuild time are accurate. It takes around 8 hours to rebuild my 120 GB 1+0 RAID (four 60 GB 7200 RPM drives).
And keep in mind that the 2400A is a SCSI RAID solution retrofitted onto an IDE interface -- some of the 2400A's firmware is shared with Adaptec's SCSI RAID firmware. So the 2400A is not really built or optimized for IDE from the ground up.
But if you need RAID 1+0 or RAID 5 data protection, and you have 4 inexpensive IDE drives to use, the 2400A is nice. It's twice saved me from losing any data. Don't expect blazing-fast performance, though -- just consistently good performance, very low CPU usage, and very strong reliability.
I built a Pentium 3 gaming system from almost the ground up and decided as games seem to be having longer and longer load times, I'd get an ABIT motherboard(SA6R) with highpoint raid onboard. I matched it with 2 40gig IBM drives (the ones that don't suck) and the speedup in desktop response time even in non-gaming tasks was immediately noticable. To help offset the statistically halved reliability, I have the drives mounted in a cage with 2 case fans blowing cool air over them.
That motherboard died slowly as the capacitors blew out one by one, but it didn't kill the RAID array. Since I didn't have a full backup of the entire volume, I replaced the motherboard with another ABIT motherboard (KR7A) using the next edition of the same highpoint controller, but using an Athlon CPU this time. The RAID volume was fortunately recognized immediately, however the old windows install was unrecoverable because I never could convince windows98SE setup that I was now using a VIA chipset instead of the Intel 815. I ended up deleting the windows directory, re-installing windows, and then re-installing all my software over the old installations which saved all of my data and most of my non-registry application settings. This process was reasonably quick due to the high speed of the drives.
On the VIA chipset motherboard the RAID array is slightly slower than on the Intel board, however VIA released a driver that recovered most of the RAID speed. It's still easily the fastest responsing computer in the house out of 4 systems, primarily due to the hard drive speed.
I don't recommend RAID 0 for anyone but the hard-core hardware tweakers because the potential for rather amazing difficulties is rather high. If the motherboard dies, I will lose the array if I can't find another motherboard or controller card that recognizes the existing array format. That's easy now, but might not be easy next week or next year. Add double the statistical failure rate on top of that (remember I'm running IBM drives, ugh), and it's definately not a solution for a system that must be reliable with quick failure recovery times.
The RAID array also makes overclocking somewhat more of a gamble. I nearly doubled my disk score under PCMark2002 with a mere 3 mhz FSB overclock, however the system also became slightly unstable and I couldn't tell if it was bad memory or the drive subsystem becoming flaky at the increased speed. Some hard drives and drive controllers are notorious for being finicky about running at higher speeds, and I've read that IBM drives in particular do not tolerate PCI bus speeds much over standard.
It sure is fast though, enough so that I don't have anything but the video card overclocked. 20-30 day uptimes on a win98SE gaming rig speaks for itself. That's horrible compared to linux, but it's outstanding for a win9x gaming rig.
I haven't had the time to try Linux on this machine and since it's both my game rig and daily-use machine and the games I play (flightsims and driving sims) don't run all that well under linux, and I don't feel like dual-booting my main rig. I run it 24/7 and in 2 years I've lost one power supply, one 80mm case fan, and one stick of DDR memory in addition to the failed ABIT motherboard. Speed is great, reliable speed takes careful parts selection.
I wonder if people here have experience with random read to RAID systems. Usually I only see specs for the sustained read/write performace for the system.
We have a couple of fileservers with RAIDs attached, usually SCSI-IDE RAID systems, some SCSI-SCSI. While the sustained read is usually equally good, i.e. only depends on the host-interface, the random read under heavy load is really crappy for the RAIDs with IDE discs. And with crappy I mean ~10MB/s not 150MB/s with sustained read on the very same system. Is that expected?
The pseudo randomness of the access pattern commes from a cluster. As clusters are popular these days, and almost always produce rondom like access patterns, shouldn't people pay more attention to that?
Any experience/insight would be welcome.
Cheers, Peter
KdenLive/PIAVE - non-linear video editing
This is when you realize how scary it is that i and o are right next to eachother on the keyboard =)
I seem to remember that there is something about the NTFS file system and Windows XP that prevents doing this. However, I would like to know more about it. There are free SID changers, so that is not a problem.
I like reading the comments here, I am humble enough to know I can always learn something. But there's something I didn't see mentioned, in all these IDE RAID setups that people describe: can you have a hot spare disk? Hot spare is critical for data reliability. If you have a large RAID 5 or RAID 0+1 (not advised, always do 1+0, whenever possible), you can do the math and see how darn important it is to have the host spare.
What good it is to have a RAID 5 without a hot spare, when you can only guard against single drive failure? So, I really hope IDE RAID supports hot spare, otherwise I question the saity of mind of the admins who implement such solutions.
As for IDE vs SCSI drives, I have to say that I will always go with SCSI, as long as I am in a multuser environment where seek times are critical. Apparently (experience shows), if you put your database space on a RAID, seek times are critical for the performance of your application. In this context, I think this review/coparison would have benefitted from a real-life aplication's benchmarking, with a database hosted on the RAID.
Sigged!
Do you _need_ to boot from CD as a requirement? I am sure you know, but you could load from floppy or loadlin and even if loadlin doesn't work, you could install an older version (Win98?) of Windows and load it from there. In this extreme case, you could initially use the same partition you'd use for Linux for the Win98 install, and go on from there.
Not really. It's more a matter of convenience since I try every major distro every few releases.
You're missing the idea that many (most?) RAID 0 setups use 2 identical drives. My RAID controller documentation specifically indicated 2 issues regarding the drives used. First, it indicated that performance would suffer if two different drives would be used. Not MIGHT, but WOULD. Second, it said that if drives of two different sizes were used, the total capacity would be twice the size of the smaller drive.
Based on those two issues, it seems reasonable to think that many (most?) people making RAID 0 arrays would use two identical drives. I know I did in my RAID 0 setup.
I have three 40gb hard drives and am looking for a similar solution. Basicly, I want 20gb for NTFS (win2k), 20gb for ext3 (linux), and 80gb of shared fat32 (raid0) space. I'm gonna play around with this over the next few days. If I need info, can I send you an e-mail?
You can send me an email, but I can't guarantee I'll be able to respond right away. It's the end of the semester and I have finals coming up.
Two things you might want to keep in mind:
-From the numbers you gave, it sounds like you want to split one 40gb disk between the two OSs and set up the other two in raid0 (just because everything divides up so nicely). It's more awkward with two OSs and three disks (I have two OSs and two disks), but if you can manage to involve all three disks in the array you'll get a significant performance boost. You won't quite max out a 32 bit 33MHz pci bus, but you'll come close (at least in sustained read transfers).
-Theoretically, you should be able to format partitions of up to 2TB with fat32; however, windows 2000 and xp will only let you format partitions of up to 32GB -- well below what you need. If you end up formatting it with ntfs, be aware that linux write support for ntfs can destroy your data, so don't enable it. Also, some distros (redhat at least) don't ship with ntfs support for legal reasons. You have to hunt around on the net for an add-in rpm or compile the kernel yourself.
Have you thought about drafting a howto?
Sorry, but I don't think there are enough people that want to share win/lin software raid setups to make it worthwhile.
so bad that I can only suggest to avoid it when possible ! Sometimes cost-considerations force one to use IDE RAID, which is the only reason for it to exist IMHO because so far I had only trouble with it.
:-).
Well, to be precise with Promise IDE RAID, that's all I can talk about. Problem is they only release binary drivers, and if you need to run a Linux distro or just a kernel that isn't supported by them you're lost.
We had to install several servers with Promise FastTrak 133 IDE RAID controllers, and we had to run Linux and VMWare with Windows 2000 Servers on it (don't ask
Problem was, those machines where dual-processor, and the normal SuSE 8.0 SMP kernel uses PAE (aka 64 GB RAM support), but VMWare doesn't support this. But Promise only provides modules for the SMP-64GB and Uniprocessor kernel. No support for Debian or SuSE 8.1 or SuSE SMP-4GB. To make a long story short, in the end we were forced to use software RAID, which is an ugly solution but one that works.
If we had used those excellent Adapted SCSI RAID adapters from the beginning we would have saved us a LOT of trouble and time, and with time=money we would probably have spent the same amount of money plus have a solid solution that we planed from the beginning.
Which files in particular can't you copy? Can you not access the data, or does the file not work when written to the target system?
--
Benjamin Coates
Did your IDE setup have a decent UPS and power supply? If it didn't then you may be blaming the wrong thing for the problem.
RAID is only for disk failures, not other failures. Backup is for other failures.
18GB SCSI 10K rpm drive vs 120GB ATA 7200 rpm drive.
;).
Partition 120GB drive so that you only use the fastest 18GB of it.
Now compare random access seek times. Only seeking 15% of 120GB drive
If 120GB ATA drive is too expensive. Test with an 80GB drive.
Not sure what the results will be, but it's worth trying don't you think?
Some drives would probably be better at short seeks than others (settling time etc). Don't see much info on this tho.
Using 2.(2, 4, 5).anything, and two different Abit RAID motherboards with either a Highpoint 370 or 372 chip, and either ReiserFS or Ext3, all I've had is endless hassles, data corruption, data loss, unrestorable boots, unmountable RAID arrays (both 1+0 and 5), an endless cycle of mkraid --dangerous-no-resync, mkraid --really-force, etc. etc. and of course, the obligatory restore-from-tape. Not to mention the endless VIA hassles with DMA, hd timeouts, and now, trying to restore, osst drivers dying and panicking where they once worked. ...I think the extent of it is RAID and IDE don't work reliably on Linux. I'm *completely* losing my faith in it. OSST (OnStream tape drives) are no longer supported (the old ones haven't been updated since mid 2001), and Linux in general is starting to become more hassle than it's worth for serious use.
There are valid performance and reliability reasons for using SCSI drives instead of IDE drives; the question is whether these gains are worth the cost, not whether they are there at all.
Reasons why SCSI might be worth it:
- Spin rate. Until IDE drives gain 10k and 15k spin rates, SCSI drives will always be king in multitasking and random-access situations. 3ms seek time is so much better than 10ms that you have to use it to believe the difference.
- Reliability. IDE drives have one year or at best three year warranties. SCSI drives have five year warranties. You can run modern 15k scsi drives stacked next to each other with zero additional case fans and expect to outlast your warranty. Try that with IDE.
- Hot swap. Does anyone here know of a hot-swap IDE raid solution? I think not.
- Tagged command queuing. A SCSI drive can collect multiple drive requests and reorder them to optimize the actual physical retrieval of the bits in question. IDE drives, even if the box lists this feature, have never done TCQ particularly well. This kind of thing is impossible to benchmark because its benefits only show up under heavy multitasking, not single-tasking benchmarks.
For most people, I would agree that you would be better off buying 2GB ram or two CPUs before spending money on SCSI. However, if you already have 2GB ram and two CPUs, and you still need more, then that's when you should look into high end SCSI.Something very odd about the single-drive ATA 100 results here. Anybody have a theory? To me, it looks as though the test is broken.
Have you got your LWN subscription yet?
You can't simply add the MTBF together
depending on the system it would be similar to the form
(1/Msys)^exp = (1/Ma)^exp+(1/Mb)^exp
Msys being system MTBF
Ma being for element a
Mb for element b.
Failure mode and distribution affects the exponent.
And this is only approximate, and loaded with assumptions.
More often than not, something ends up going wrong that would/could not have occurred had they followed my advice in the first place, and then I hear about it.
Having been there and done that, the most important thing (at least in a professional environment) is to make sure you document your recommendations! You may also wish to document your specific concerns with respect to the course being followed that's against your recommendations.
Not so important with friends (hopefully), but in a professional relationship it can be crucial to be able to whip out the e-mail/printed report you sent six months ago when the client comes back all miffed, especially if you perform regular maintenance on their network (for example) and they're now blaming you for their data loss.
It could be worse : you could be telling me damn lies about your benchmarks.
I personally would love to hear any ide-raid stories that slashdotters might have.
This one time, at IDE-RAID camp, a girl stucka f lue up her pussy.
I've been working on x86-based servers a long, long time.
:-)
There are many reasons one should choose SCSI over IDE, but I want to counter a few of the arguments I've read through the many messages here:
Argument #1:
SCSI can have 15 devices per bus, but why buy more smaller and more expensive SCSI drives instead of getting fewer large IDE drives?
Answer: Bigger isn't always better. On large RAID systems (real servers, here people...not Mp3 servers) one of the concepts of RAID5 is to spread out the data among as many drive spindles as possible. This keeps each drive's load level under control, and eliminates hot-spots on individual disks. If you sit down with any SAN vendor, like EMC, they will tell you the same thing.
Argument #2
Sustained IDE Raid performance can equal SCSI
This is absolutely incorrect. This may be true on a server with no CPU load. Try this again on a server running SQL and averaging 85% load. You will NOT see the same performance out of an IDE disk layer. There is simply too much CPU overhead on an IDE-based RAID system for heavy-load systems. The idea behind a SCSI controller is that it is free of the system's CPU as a bottleneck. The money saved on non-SCSI hardware will instead need to be spent on faster CPUs.
Argument #3
IDE Disks are just as reliable as SCSI
Again, completely false. You get what you pay for. SCSI disks have logic on each disk to control the operations OF that disk. In a RAID array, you want each disk to be completely independant of the others. IDE RAID requires the controller to do all the monitoring (if there is any) of each disk, lowering performance of its primary function--controlling disk I/O. Anyone who has worked on a Compaq server and used Insight Manager will be able to see the advantages of SCSI disks directly. SCSI disks will be more reliable since they are built to be more reliable. IDE disks are meant for cheap deployment on cheap systems.
Thank you, have a nice day
-brain
Do you have any product to recommend for IDE-SCSI adapters? I only found this, but they don't seem to be distributed too well, esp. in Europe. If it works well, $100 per drive is quite cheap.
Windows XP will not copy its own registry file, for example. Without the registry, the OS is useless.
However, this behavior does not affect the ability to do a sector-by-sector partition copy under Linux. I don't know if that is possible, or what Linux tools to use.
yes, I use them and have good results. I was surprised that the review got the worst write performance of any system on them. Really bad. It was very unclear why.
I don't quite understand where this Inexpensive crap came from.
I though RAID was developed back when a pc's hard drive was called a winchester, and it floppies were 8 inches. Professional hard drives were the size of a washing machine and had removable disk packs.
At that time anything less than $50K for reliable mass online storage was inexpensive.
Apocalypse Cancelled, Sorry, No Ticket Refunds
I agree. Can you recommend some software to me? I'll try it.
This would be my 801st. Hehehe, check out # 800, it'll be Mod-riffic!
Is it less prone to media errors like regular IDE devices are. Also, does it lower CPU usage? IIRC the actual drive media is the same for scsi and IDE drives, only the electronics are different.
... Governments are instituted among Men, deriving their just Powers from the Consent of the Governed...
There is third-party software that does work (mostly) for copying Windows XP sector by sector. Looks like that is better.
> Where would random come into it?
... at any time.)
Well, like I said,
>> (The term "Random" means the same as in RAM -- i.e., that
>> you can access any part
In other words, you can read or write the data in any order (Just
like you can with a SLED, BTW.) These days, a non-random disk
array is neigh unto inconceivable, of course.
> Alluding to the fact that if one drive fails you still have two
> others that have a complete set of the data in the array.
No, that isn't how it works. The original concept was "redundant",
but not _that_ redundant. Actually, what you describe is close
to the kind of redundancy I want -- Federation redundancy, i.e.,
everything in triplicate. But current RAID designs are mostly
not that way, and RAID 0 implementations have no redundancy at
all; if any of the drives go bad, you'd better have backups.
RAID 1 (and higher) are correctly described as "redundant array
of inexpensive disks", but RAID 0 is non-redundant. This is
what I meant when I said some RAID are done just for performance
reasons.
If you want to understand partial redundancy better, read the
article. In brief, RAID 1, 0+1, and 10 give you two copies of
each piece of data; RAID 3 and 5 give you parity, which uses
less disk space and can be just about as good.
Like I said, though, what I really want is everything in triplicate.
I guess that's where offsite backups come in... which is better
anyway, because if the building burns down, your whole RAID is,
like, gone, man.
Cut that out, or I will ship you to Norilsk in a box.
I will soon be trying the newest version of Ghost. I've been trying PowerQuest Drive Image and DeployCenter, and it is rather flaky the way it is designed. The old version of Ghost (4 years ago) were worse.