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Hardware IDE/SCSI RAID for Windows 2000 Servers?
reezle asks: "Mostly I was wondering what other sysadmins have been doing for Mirroring or RAID-5 in their w.2000 servers. I really don't like the M$ 'Enhanced' disks that allow for RAID, since I've actually lost a volume during the conversion from 'basic' to 'enhanced', and also I worry that I will get locked out of the volume if the OS goes belly-up on me. There is also the idea that software RAID is much slower, but it's cheap, and so are some of my customers. What kinds of solutions are being used successfuly? What kind of recovery nightmares have people run into? Is IDE RAID ready for the real-world server market yet?"
Seriously, Ask Slashdot question for this??
Toms Hardware IDE RAID review
IDE RAID without hardware
Exercise left up to reader: Finding SCSI RAID reviews
What would it cost for your company to reconstruct the lost data?
Risk Analysis argument over!
Seriously, the Win2K volume management and "enhanced disk format" you worry about are a subset of the Veritas VM, licensed by MS. It's crippled without many of the data-recovery features, and doesn't include the file-system enhancements.
When you convert a Windows volume from "Basic", you are essentially performing the same operation as "Encapsulating" a native volume with Veritas on Solaris or HP/UX.
"Flyin' in just a sweet place,
Never been known to fail..."
Well, I've never had the problem you had when going from Basic to Dynamic, but when I was doing software mirroring, it was on a HP LPr rackserver with a pretty simple 2 disk setup. All done through Windows, never noticed any before/after performance loss. In my testing, I had to do was move the original disk out of the slot, put the mirror copy in it's place, and it booted right up. Then if I broke the mirror it was ready to start all over again.
Right now (moved on to a different - less technical - company), I have a Dell PowerEdge server that I inherited using a PERC 2/Si RAID 5 config. Windows 2000 (just upgraded from NT4) is none the wiser as to how it's setup, and lists the disk as Basic. Downside is, the Dell RAID setup is pricey, and if your customers are cheap, well...
If worse came to worse, I'm sure booting off of the Win2k CD and going into the Recovery Console with a will save you if the drive does act flaky, but I dunno the specifics on that.
Here at my company we have a devel win2k server with RAID5. I believe the card is a Mylex DAC-960 of some variation. It works pretty well. The real pain with that machine was the onboard SCSI controller and Win2k not dealing well with it(something about a Zero-Channel RAID Storage controller & SCSI Interrupt Steering Logic). But the Mylex(now owned by IBM i think) card just pretty much worked.
Seriously - don't bother with anything else if you're gonna do IDE RAID. Drivers for lots of OSes besides Windows, too (including Linux). I just wish they did OS X!
Keep in mind that unlike the SCSI RAID you can get from Dell and the like, IDE RAID is NOT HOT-SWAPPABLE.
This means that if a drive fails, and you want to replace it, you must take down the system if you use IDE RAID. With SCSI RAID, and the apropriate controller, You can literally pull the dead drive and replace it with a new one, and the machine doesn't even skip a beat (well, it slows down a little bit as it rebuidls the array, but...).
First - 3ware makes an excelent line of IDE hardware raid cards if your too cheap for SCSII.
Secondly - Windows Software raid will blow up in your face - especially Microsoft's version. If 'lost' three RAID arays to Promise, and four to Microsoft before getting a clue and forever forsaking crappy software. Windows Software RAID sucks so hard, that even if they fix it now, it's suckyness will caryover for years.
So you really have two choices for Windows RAID - SCSI or 3Ware.
Aside: Too bad Microsoft and Promise are too stupid to review NetBSD's RAIDframe - this is software RAID done right. Totally abuseable - you can pull out an IDE cable and it just keeps chugging along. Easy to set up as well - no guessing if it's going to work, it just does.
Moneyed corporations, non-working 'poor' and criminal prisoners are turning productive citizens into tax-slaves.
$300 will buy you a decent 3ware Escalade 7410 card, which comes with both Windows and Linux support.
Promise IDE RAID is a lot cheaper, but unreliable; I would get kernel trap exceptions all the time and it wasn't worth the trouble. Asides from a problem setting it up where the onboard motherboard ATA-100 driver was conflicting with the 3ware card, I haven't had so much as a hiccup. There's an erroneous report that says they only work on 64 bit PCI, but they work fine on 32 bit as well.
With CPU speeds being what they are, IO is really the bottleneck in your average computer. I've seen dramatic since the card went in -- I'd guess compilation time has halved.
If you're starting fresh, see if you can get a Tyan motherboard and 64 bit PCI and you should have no problems for the forseeable future.
Software RAID-1 is actually quite fast. In my benchmarks it is as fast or faster than a hardware RAID-1 solution on Linux. I'd expect that MS's implementation performs similarly. It is very cheap to implement :)
If you're doing raid 5 (or 10) you could benefit from more horsepower. You have a few options. They are (in rough order of cheaper cost --> better performance and reliability)
- Buy faster CPUs to make up for the overhead of software RAID-5 or RAID-10. They will still not be as fast as a hardware solution, and it might be a real pain to deal with in a disaster situation. Make sure you have lots of backups.
- Use the 3ware 7850 card to get you cheap IDE RAID-5. Obviously the benefit of this is that you can save a ton of money on disks. In my experience the card performs reasonably well and is stable, but I have to admit I've only been using it for non-critical fileservers over the past 6 months. It may not be a mature solution for all uses.
- Buy a classic SCSI hardware raid card (like a Mylex AccellaRAID 320) with a large battery-backed RAM cache. This type of card will give you the highest performance, and you can safely enable write caching as well, which will tremendously improve your RAID-5 write performance if that is the RAID level you want to use. It's a rock solid, but expensive solution when you count the cost of the scsi drives.
Some pitfalls:
Don't use IDE (hardware or software) RAID with Promise controllers. I don't really have any proof, just lots of annecdotal first and second-hand reports of craptapular performance and instability.
is promise really that bad, or is it just bad like using athlon CPUs in a business server would be bad?
I use Promise FastTrack RAID controllers in a mirror configuration (two drives, one on each cable) in 15 Novell servers. I have both 66 and 100TX2 models in service (most of them for over a year) with no problems.
I also used one on my workstation (striped, two 7200RPM 20GB drives) for the better part of last year and it sped up my computer substantially with no problems.
When a server has gone down then usually both hard drives have good, valid data. When one hard drive goes down the other keeps trucking until I replace it (offline - I didn't get hot-swap enclosures, it happens so infrequently it's not worth it).
So for the low end (ie, CHEAP) hardware RAID from Promise is right on the money. If you want something without such bad anecdotal evidence (as attested by other posts in this story) then you will have to pay more.
As always, your customers get what they pay for. So far my company's investment has paid off over and over again - I don't have to recreate the entire server from the ground up (or from a backup) when at least one hard drive is good. I've had to replace 4 servers in the last year and one or both hard drives have always survived whatever caused the server to go down. (These are low usage, but physically punished servers)
-Adam
The real answer is to use server class hardware from a real supplier. Both Dell and Compaq have rather solid server offerings with hardware raid built in. No need to worry with MS's implementation. And if you're doing RAID 5, you really should be in hardware anyway, or performance will kill you.
If this is for home use, or for fun, then play all you want. But since you're paying for windows anyway, you might as well poney up for real hardware. Your life will be happier for it.
Zapman
If you're working for a company just get a decent server with hardware RAID. Dell's servers use Perc2 or 3 cards which can support upto a metric buttload of drives (12-16? not including 2-4 external connectors). Win2k can use all of the cards nicely and will let the controller do its thing. Most Linux distros come with drivers for them too if you want to make sure you aren't stuck with win2k.
Poweredge 2550's can carry 4 drives and are fairly cheap by company standards (~$5k decked out).
Notice: I do not work for Dell, but I am a Windows admin for a company that does buy from Dell
The nature if IDE is Synchronous transfer..Only one drive can talk at a time. RAID is ok on ide for redundancy but will never be anywhere near as fast as a SCSI drive. I would never implement IDE RAID in an enviroment other then just to play.
Well this seems to be as good a place as any to ask this question. Has anyone out there tried one of those SCSI -> IDE RAID arrays? I only know of a couple of companies making them:
Promise UltraTrak series
ACS-8xxx
Anybody know how well these things work?
The other thing I like about these is that since they have a SCSI interface to the array you could get a SCSI RAID card and RAID the RAID arrays. Not sure what that would do but it would be fun trying it.
I myself am running sucsefully a RAID5 system based on the software solution of Win2K.
I use 5 Maxtor 60GB drives (don't ask me for the type, I am too drunken to remember) having a redundant failsave 120GB online.
It's fast enough for my pr0n collection and I allready had a harddrive failure, so I just exchanged the drive by a new one with a harddisk of the same type (my vendor exchanged it without asking) and all I had to do was a right-click and 'enable' in the drive-manager.
I just like it to have the opportunity to create a RAID5 system by software without worries about controlers, harddisks, drivers, etc.
Yes, sure, software-based allways is slower than hardware-based, so I wouldn't use it in a webserver (especially if it could get slashdotted). But it's fine for a fileserver in your company as (backup-)server or for your machine at home.
I only ensured to use 5 identical HDs...
Just look for hardware RAID cards with Windows 2000 compatibility. A monkey could do this for you, if you feel like training the monkey for a few hours.
Here is what my monkey found.
"Remember when the U.S. had a drug problem, and then we declared a War On Drugs, and now you can't buy drugs anymore?"
There have been some bumps with the hardware, but 3Ware has been responsive to our bug reports, and our current revs of the drivers/firmware have been solid. The drivers have been incorporated into the main kernel, and you can download the latest driver from 3Ware's site.
The 3dm software is great for managing and monitoring the arrays. It has a web interface, email notification, and SNMP access (I think).
Give them a fair evaluation and you should be impressed.
Method of processing duck feet
There are some rules you must follow:
1) If you have a server NEVER EVER EVER used IDE for Harddrives!! SCSI consumes a lot less resources than IDE and it is fast. IDE raid will never be ready for realworld servers as it uses the CPU too much, SCSI has it's own CPU.
2) Software RAID is evil. It is too unpredictable. Use a good quality (read Adaptec) SCSI RAID controler, we use the Adaptec 2100S
3) Don't skimp on hardware for servers, they may cost a lot but it's better to spend now than later. If you are using M$ windows, invest in a REAL server motherboard (Intel), ECC RAM, SCSI RAID, IBM Hot Swap, Harddrives, good backup tape drive.
The one rule I have learnt with servers is that when the server goes down at 9:30am, you want good hardware not the cheap piece of crap.
Intel motherboards are the bees knees of motherboards. They almost never fail, are over engineered, and have the best management features around.
There are also ATA drive chassis available that have some onboard electronics that allow the drive, mounted in the chassis, to be hotswapped into the appropriate recepticle, although I am not as familiar with these as I am with the SCSI drives (I have 3 of them in my desktop machine that I built and learned a great deal about SCSI in the process of getting everything working).
UNDER NO CIRCUMSTANCES SHOULD ANY DRIVE, ATA OR SCSI, BE "HOT SWAPPED" IF IT PLUGS DIRECTLY INTO THE BUS AND POWER SUPPLY. THIS WILL RESULT IN DAMAGE TO YOUR DRIVE AND QUITE POSSIBLY YOUR DRIVE CONTROLLER.
Friends don't let friends use multiple inheritance.
SCSI vs IDE
1) SCSI drives have low seek times and higher transfer rate for three reasons.
1.1) The SCSI bus operates faster (around 160mb/s)
1.2) SCSI drives spin faster
1.3) SCSI does not use the CPU to transfer data. It uses DMA
2) Hard vs soft
Hardware raid is invisible to the OS (almost). So in recovery situations it is better. Plus hotswap is just cool.
As an interface, the difference between SCSI and IDE is small. Yes, Scsi has a few more controllability and asynchronous features, but these are not a big deal. The difference is that the manufacturesers use Scsi is a marker for a generally higher level of build quality and testing. Just as PCs marketed as servers are built better than desktop workstations, SCSI drives are simply better built than IDE ones. The price difference is not the trivial/zero cost of the different interface, it is better bearings, stronger actuators, more rigid cases, bigger buffer rams, cleverer firmware, extra levels of ECC, more vibration testing and so on. Check the MTBF figures - when I last looked, SCSI drives had 5 times the MTBF of comparable IDE drives from the same manufacturer. Basically, IDE is designed down to minimum cost for the cutthroat desktop/home market, while Scsi is designed up to beat the competition in the less price sensitive server market. [Most of this derived from talking to the tech support of a major disk manufacturer]
Which means that if you really, really, want your data to stay there, the delta of SCSI is probably worth it. OTOH, I would go for Raid-ed IDE before non-Raide-ed SCSI - drives fail, even the best.
There is no technical reason why IDE cannot be made host-swap - but not in an ordinary PC case. You need a mounting enclosure designed to make/break contacts in the right order, and a controller designed for hot swap. These cost money, and people tend to put that money alongside the premium features already in Scsi rather that the minimum-cost IDE.
Consciousness is an illusion caused by an excess of self consciousness.
The Hardware scsi was by far the easiest and best performing of all of them. The controller (adaptec 1000U2 series) had a nice simple menu and was the only one which allowed me to include the system partition in the raid 5.
Our software raid 5 had to be setup once we had the machine up and running, so we couldnt include the system partition, and it ran very slow when do large file transfers.
Our Ide one we did the least testing on, since by the time we got around to it, we had decided to go with the hardware scsi. It ran ok, faster than the software scsi one, though still slower than the hardware scsi. It also wasnt hot swapable either, but that was only a minor concern for us
Check out the ARCO IDE Raid Controllers ... they build a number of devices that basically sit between your iDE controller and the hard drive and mirror the hard drive transparently.
... but seems quite solid.
It's only RAID 1, and there isn't any performance benefits
You setup the controller with 2 or 4 drives on it, and your system basically sees 1 or 2 drives. All writes done to a drive is automaticlay done on both drives of the mirrored pair.
It's a hardware solution, so it's OS independant.
mm
We have a Promise RM8000, an external SCSI device that houses an IDE RAID unit with 8 drive bays.
When we first installed it, we put four 160 gig drives in it and created a RAID 5 array formatted as an NTFS volume. We needed the space right away, so we started using it.
When the remaining four 160 gig drives came in, we converted the disk to a Windows "dynamic disk". This allowed us to simply plug in the four new drives and extend the existing volume onto them.
After a day or so of whizzing and whirring the RAID 5 array was happy with its reorganization and we had a happy little 1 terabyte volume. And in case you are wondering, yes, it really did take almost 24 hours before the RAID array stopped shuttling data around. The volume was available for use immediately, however.
A couple of weeks later we added a high-speed SCSI scanner onto the same SCSI chain as the RM8000. Suddenly the drive was not visible in Windows anymore. We checked for proper SCSI termination, etc., but it wouldn't show up.
We removed the scanner and put all cable and termination settings back to their previous values. The drive showed up again, but Windows said that it was Unallocated!!!
That's right...our 1 terabyte drive was gone...poof! We had 600 gigs of data on that thing!
Promise told us that what we were describing was "impossible". Microsoft also had no explanation. Thanks...thanks a lot.
I probably won't touch IDE RAID or dynamic disks ever again, unless I see some real proof that they have become much more reliable.
"Scientists prove we were never here."
-- Devo
I have a Highpoint Rocket Raid 100 in my stereo, working fine so far, with 4 drives in 0+1 config for 160 Gb under NT 4sp6a.
Haven't (yet) tried to replace one of the drives, but the initial install was ez.
Cheap customers hmmm...
Give me a second, I'm having trouble with the concept of Windows(AnyVer) and reliability.
Nope, can't do it 2K is more reliable than Win3x or Win95 or Win98... But I just can't put reliability with it.
Have you considered using a *nix system for backup of the Win system?
Cost being a deciding factor, the trade is going to have to be in potential loss of data,
depending on the load you could give the customer tiered options for recovery of data.
You sir, have a very impressive monkey.
XML is like violence. If it doesn't solve the problem, use more.