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How TF are you getting RAID-10, which requires 4 drives, out of two drives? I'm guessing you mean RAID-0 built around two drives. Maybe you have something funky like RAID-10 built from four partitions on two drives, but that makes your redundancy moot.

How TF are you getting RAID-10, which requires 4 drives, out of two drives? I'm guessing you mean RAID-0 built around two drives. Maybe you have something funky like RAID-10 built from four partitions on two drives, but that makes your redundancy moot.

Actually if you use RAID level 10 you get speed and mirroring. You'll lose 50% capacity (same as a normal mirror) and need 4 drives to implement.

Sorry, but you seem to have raid's 5 and 10 reversed in your post.
Only raid 0 is faster than 10 (without proprietary equipment). Raid 5 is quite slow and 6 is even slower, especially for writing.

http://www.pcguide.com/ref/hdd/perf/raid/levels/mu ltLevel01-c.html

general RAID info (pictures)

http://www.acnc.com/04_00.html

http://www.pcguide.com/ref/hdd/perf/raid/levels/in dex.htm

RAID 0 = No data security, fastest reads, fastest writes.
RAID 1 = Redundant data, moderate reads, slower writes. Depending on setup, can sustain multiple concurrent drive failures
RAID 5 = Better than 0 for data security (but not as good as 1) and faster than 1 for read / write but not as secure. Cannot sustain multiple concurrent device failures.
RAID 1+0 = Stripes over mirrors. Requires a minimum of 4 drives to implement, but has the same data security as RAID 1 (in a similar configuration). Better read/write performance than RAID 1.

Hope that's helpful

-FB

There's an excellent guide to RAID levels (with pretty diagrams and such) at http://www.acnc.com/raid.html

Actually, for RAID 5 you'd need a minimum of 3 drives.

http://www.acnc.com/04_01_05.html
http://en.wikipedia.org/wiki/Redundant_array_of_in dependent_disks

First, always rip in a lossless format. Other people have mentioned some. Just pick any one that's open source and popular (I recommend FLAC).

Second, store them on a RAID. I recommend RAID 6 . It's a lot like RAID 5, which is becomming more popular with real archivists and can sustain mutliple drive failures without outrageous performance and storage overhead. It requires some investment in hard drives, but honestly they're so damn cheap that's no big deal.

Your cheapest solution will be to go SATA as there are several very large drives available for little money and more and more hardware RAID cards. Quite frankly the system will be fault tolerant so spending lots of money on more reliable SCSI drives is a waste. And do buy an excellent hardware RAID 6 card. Software RAID 6 has incredible overhead making the computer a dedicated file server that can do little else.

Check out RAID solutions. Particularly RAID 6 (which is very similar to RAID 5).

As other posters have mentioned, software raid is fine for RAID 0, 1, 0+1. As you get to RAID 3,RAID 5, and RAID 6, however, your processing requirements go up quite a bit.

A SATA RAID 5 card with hardware XOR engine and a DIMM slot for cache might be a cost-effective option for you. (Goes for ~$180 on Pricewatch, or ~$240 on Dealtime)

Oh, and I would have goine with HGST, Western Digital, or Seagate for your drives... but I suppose hardware failure is what RAID 5 is for :)

As other posters have mentioned, software raid is fine for RAID 0, 1, 0+1. As you get to RAID 3,RAID 5, and RAID 6, however, your processing requirements go up quite a bit.

A SATA RAID 5 card with hardware XOR engine and a DIMM slot for cache might be a cost-effective option for you. (Goes for ~$180 on Pricewatch, or ~$240 on Dealtime)

Oh, and I would have goine with HGST, Western Digital, or Seagate for your drives... but I suppose hardware failure is what RAID 5 is for :)

As other posters have mentioned, software raid is fine for RAID 0, 1, 0+1. As you get to RAID 3,RAID 5, and RAID 6, however, your processing requirements go up quite a bit.

A SATA RAID 5 card with hardware XOR engine and a DIMM slot for cache might be a cost-effective option for you. (Goes for ~$180 on Pricewatch, or ~$240 on Dealtime)

Oh, and I would have goine with HGST, Western Digital, or Seagate for your drives... but I suppose hardware failure is what RAID 5 is for :)

you do NOT want RAID 0 for fault tolerance, it isn't it is for PEFORMANCE! for budget minded fault tolerance you need at least RAID 1 http://www.acnc.com/raid.html

You've got something more like RAID 0+1 then. The controller may not see it, and the performance characteristics may not be the same, but that's how it's stored across your disks.

Also note that while the subject line just says "RAID-0 is stupid", I qualified it more in the post with "on data [you] care about". Other people have posted some legitimate uses for RAID-0, basically all situations where the data just aren't very important or can be restored from other media quickly and easily. That's not often true.

Err, RAID-4.

RAID-0 = minimum of 2 drives. RAID-10 = minimum of 4 drives and really needs a more fancy RAID card than that £15 thing you picked up from eBuyer. RAID levels.

Woa, are pound signs working now? :o

Please see the BAARF pages, or even read Advanced Computer & Network Corporation Raid.edu pages.

This should at least leave enough time for a hot spare to rebuild before another drive goes, which can be a problem for RAID 5 (as noted here).

Is this being used anywhere?

Actually, RAID 5 distributes the parity across all the disks. RAID 3 would have to calculate parity for every read (unless, of course, you lost the parity drive). So for RAID 5, you only need to calculate parity for 1/N of the disk reads. Still, performance will be degraded, but not quite to the same level as RAID 3.

Actually, RAID 5 distributes the parity across all the disks. RAID 3 would have to calculate parity for every read (unless, of course, you lost the parity drive). So for RAID 5, you only need to calculate parity for 1/N of the disk reads. Still, performance will be degraded, but not quite to the same level as RAID 3.

I'm a big fan of RAID 10. With the cheap price of space these days, you can basically have the best of both worlds: faster perforamance and more dependable than a single drive.

Though RAID 5 is the most popular I've found the write penalty to be a problem. And rebuilds are slow. Anyways, check out this page about different RAID types. I found it most helpful.

Cheers.

keep in mind that raid 5's write performance can be pretty nasty. at worst, a single write can require a read from each drive, parity calculation, and a write to record the new parity. raid 5 is great for things like static webserving where reads outnumber writes by a large margin, but for storing something user's home directories or a database with lots of writes, it's best to make sure your raid controller can optimize away the write performance hit, as most do, but you get what you pay for in a lot of cases.

personally, i like raid 10 better than 5 because i don't mind trading a disk for real redundancy. parity-based raid levels require the controller to do more work in normal operation and a lot more in rebuilds. i prefer to just copy the good drive from the mirror to the replacement drive.

anyway, ac&nc's raid.edu has a lot of good info on the advantages and disadvantages of various raid levels.

Try RAID 5 or RAID 10 (not to be confused with RAID 0+1). This site has a nice overview of all the RAID options. And, of course, Wikipedia has some info.

Quick overview:
RAID 5 - Requires at least 3 HDs (many times implemented with 5 - can be used with up to 24 I believe). Data is not mirrored but can be reconstructed after drive failure using the remaining disks and the parity data (very similiar to how PAR files can reconstruct damaged/missing RAR files for the Newsgroup pirates out there). % of total space available dependent on number of drives used.

RAID 10 - High performance, but expensive. You get ~50% of the total HD space as it is fully mirrored. So, 1 TB total disk space nets you 500 GB total storage space. Your data is mirrored so if one drive fails you do not lose everything. However, if you experience multiple drive failure you can be in big trouble.

Try RAID 5 or RAID 10 (not to be confused with RAID 0+1). This site has a nice overview of all the RAID options. And, of course, Wikipedia has some info.

Quick overview:
RAID 5 - Requires at least 3 HDs (many times implemented with 5 - can be used with up to 24 I believe). Data is not mirrored but can be reconstructed after drive failure using the remaining disks and the parity data (very similiar to how PAR files can reconstruct damaged/missing RAR files for the Newsgroup pirates out there). % of total space available dependent on number of drives used.

RAID 10 - High performance, but expensive. You get ~50% of the total HD space as it is fully mirrored. So, 1 TB total disk space nets you 500 GB total storage space. Your data is mirrored so if one drive fails you do not lose everything. However, if you experience multiple drive failure you can be in big trouble.

Try RAID 5 or RAID 10 (not to be confused with RAID 0+1). This site has a nice overview of all the RAID options. And, of course, Wikipedia has some info.

Quick overview:
RAID 5 - Requires at least 3 HDs (many times implemented with 5 - can be used with up to 24 I believe). Data is not mirrored but can be reconstructed after drive failure using the remaining disks and the parity data (very similiar to how PAR files can reconstruct damaged/missing RAR files for the Newsgroup pirates out there). % of total space available dependent on number of drives used.

RAID 10 - High performance, but expensive. You get ~50% of the total HD space as it is fully mirrored. So, 1 TB total disk space nets you 500 GB total storage space. Your data is mirrored so if one drive fails you do not lose everything. However, if you experience multiple drive failure you can be in big trouble.

Try RAID 5 or RAID 10 (not to be confused with RAID 0+1). This site has a nice overview of all the RAID options. And, of course, Wikipedia has some info.

Quick overview:
RAID 5 - Requires at least 3 HDs (many times implemented with 5 - can be used with up to 24 I believe). Data is not mirrored but can be reconstructed after drive failure using the remaining disks and the parity data (very similiar to how PAR files can reconstruct damaged/missing RAR files for the Newsgroup pirates out there). % of total space available dependent on number of drives used.

RAID 10 - High performance, but expensive. You get ~50% of the total HD space as it is fully mirrored. So, 1 TB total disk space nets you 500 GB total storage space. Your data is mirrored so if one drive fails you do not lose everything. However, if you experience multiple drive failure you can be in big trouble.

Learn something new everyday.

Grandparent was still wrong about the amount of space eaten by parity.

You're right. That's the difference between RAID 0+1 and RAID 10, according to

http://www.acnc.com/04_01_10.html
http://www.acnc.com/04_01_0p1.html

"RAID 0+1 has the same fault tolerance as RAID level 5" and "RAID 10 has the same fault tolerance as RAID level 1," demonstrating your point.

You're right. That's the difference between RAID 0+1 and RAID 10, according to

http://www.acnc.com/04_01_10.html
http://www.acnc.com/04_01_0p1.html

"RAID 0+1 has the same fault tolerance as RAID level 5" and "RAID 10 has the same fault tolerance as RAID level 1," demonstrating your point.

Mac 'servers', and I use the term very loosely in this case, come with, at best, RAID-0. Since you probably dont understand what Im talking about, thats mirroring.

You're wrong dumbass. Mirroring is RAID-1. RAID-0 is striping.

Um, I don't think you mean RAID 2. Maybe RAID 1?

Um, I don't think you mean RAID 2. Maybe RAID 1?

We did the same thing. Another data point.

As far as future expansion, two options, get SATA 12 port 3ware cards and the 3ware Parallel to Serial converter that 3ware sells for $30, or go with something like external ATA-SCSI from acnc that can be chained up to infinity.

You're close, but you've got raid 3 a bit wrong. raid 3 still requires a parity drive, so you lose disk space again.

The major difference between raid 3 and raid 5 is where the parity info is stored. on raid 3 all the parity info is stored on one drive, on raid 5 it's mixed in with the stripes and spread out over all the drives.

However, you are correct that raid 3 is recommended for video editing, as it has lower latency on disk writes... in raid 5 the checksum has to be done before the writing can commence, in raid 3 it only slows down the actual parity write.

Source:
raid 5
raid 3

You're close, but you've got raid 3 a bit wrong. raid 3 still requires a parity drive, so you lose disk space again.

The major difference between raid 3 and raid 5 is where the parity info is stored. on raid 3 all the parity info is stored on one drive, on raid 5 it's mixed in with the stripes and spread out over all the drives.

However, you are correct that raid 3 is recommended for video editing, as it has lower latency on disk writes... in raid 5 the checksum has to be done before the writing can commence, in raid 3 it only slows down the actual parity write.

Source:
raid 5
raid 3

Quote: Maybe such systems will be reliable (in laptops) by putting in 2 of such harddrives (RAID5?).

Nope, you are probably thinking about raid 1 (which requires at least 2 drives) where the drives are mirrored.

Raid 5 on the other hand requires at least 3 drives

One good source for the different levels of RAID is ACNC's Raid.edu

BTW: "raid.edu" is not the URL of the site, only the title.

That depends on the controller in the drive enclosure you have.

1. There are FC controllers that use IDE drives.
2. Not all FC controllers support RAID
3. Most controlers use FC-AL connectors - not SCSI.

and is a disk to disk system

Speaking of disk-to-disk, Maxtor's MaxLineII that will be out in a couple months is aimed at the mass archive/backup market.

250 and 320GB ATA hard disks, Rated the same MTTF as SCSI, 3year warantee, $400 MSRP each for the 320GB. 10TB for under $20,000.

For 1 to 10 TB this is a cheap and good solution, combined with rsync/rdiff incremental backup smearshots onto either a Linux NAS with 3ware serial ATA or direct attached storage in the form of something from ACNC or an AXUS ATA-SCSI box.

With the direct attached storage, you could scale it up past 10TB, 4.4TB per 16 disk RAID5 with hot spare, string those together on as many SCSI channels as you need. Each AXUS 16 disk box costs about $6000, 16 of the 320GB disks costs $6400, so 4.4TB will cost about $12,000. Use software RAID0 to tie them into larger volumes if you need to.

Anyway, the potential is there for low maintenence, very cheap, and automated backups using this roll your own solution.

I can't wait until the 320GB disks come out!

So raid it (1,3,5,6,10,53,0+1)

For definitions of the less raid levels(3,6,10,53)

Does anyone know of a product like this?

Yes, but you won't like the price generally, for the real plug and play units.

ACNC

Makes external boxes that you hook to a normal SCSI controller card, comes in the form of boxes that can take ATA drives, or SCSI drives. Also makes fibre channel boxes of a similar nature. Appears as one large SCSI drive to the host OS, compatible with basically any OS.

HardData

Same deal as ACNC basically, but is more of a VAR of AXUS products of this type. Penguin on homepage a plus.

Promise

Low end crappy standalone ATA-to-SCSI boxes, similar to the above ones, also makes very crappy contoller cards, only useful if you are using them for software RAID, don't use thier hardware RAID for anything. Promise cards are also picky about the BIOS on the motherboard they are installed on. Their standalone box prices are way overpriced for what you get. Their controller cards are cheap, but acceptable, for software RAID. More than one 6 channel controller per computer is not supported, more than three two channel cards is not supported. Linux kernel module is mature though.

3ware

3ware makes hardware ATA RAID controllers that are very fast, and relatively expensive. "Unlimited" number of controllers per computer, I've ran up to four 8-port cards in a single computer. Cabling is a mess when you get a lot of drives in a single system, if you need that many, seriously consider one of the above standalone boxes. Linux kernel module is open source and vendor maintained. Management software for Linux is free but closed source.

-----------------
Of course, Linux has software RAID built right in, and with a distro like Red Hat, you can set up software RAID when you install the OS in a simple GUI. You can use whatever disks you have installed, but for good results, you need to only have one disk per ATA channel, be it on your motherboard or a Promise card.

RAID Info

It took me a while to figure out, but the numbers ("0123456710530+1") in the upper right hand corner are links to different RAID level explainations.

It even explained RAID 2, which I haven't seen before.

RAID. That's what it's for.

As for arrays, beware of the benefits of striping. RAID 0 (striping) has the problem that the more drives you add, the less reliable your array becomes. RAID 0+1 (or RAID 10) mirrors the data as well and keeps your data secure in the event of a single disk failure (and RAID 10 can occassionally suffer multiple disk failures).

More RAID level 6 info
The difference between Raid 3 and Raid 5 is where the parity information is stored. With Raid 3, the parity is stored on a dedicated disk. With Raid 5 - that information is spread over all the disks. Which is better depends on what you're storing. Large data files such as graphics/image files get better performance on raid 3, while smaller files do better on raid 5.

Oh - and i messed up in my previous comment - i meant raid 1, not raid 0. 0 is striping over 2 disks, 1 is mirroring.

So you're wondering - all this theoretical info, and no practical tools to be able to actually use it.

Well - it appears that software raid under linux currently doesn't support raid 6 - but some enterprising hacker could certainly put it in (i'd assume) IANAPY (I am not a programmer yet). But RAID-5 gives us a 33% acceptable failure not, not quite 50%, but nothing to sneer at.

I did find some references to sites with a /kernel/2.2.16-1-RAID/modules/CDROM - so i'm assuming somebody uses raid+cdrom currently.

I'll let y'all know if i find something more concrete out