Raid 0 - Hard-Drives Even or Odd?

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Seraphic

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Hi, can a Raid 0 be run off of three hard drives or must it be an even number?

I've always heard that it can be any number (even or odd) for a raid 0. However, in the manual for my GA-X48-DQ6 it says: "A raid 0 or raid 1 configuration requires at least two hard drives. If more then two hard drives are to be used, the total number of the hard drives must be an even number".

Is that correct? I already picked up three of the new 640 GB WD drives and if this is true, I have a problem...
 
That is true for RAID 1, but not for RAID 0. RAID 0 is simple striping and can be any number of drives.
 
Thanks for the reply. But is it maybe different when using a hardware raid card then it would be when using this motherboard's software raid (in this case it would be software)? It is controlled with the Intel ICH9R raid controller.
 
Seraphic said:
Thanks for the reply. But is it maybe different when using a hardware raid card then it would be when using this motherboard's software raid (in this case it would be software)? It is controlled with the Intel ICH9R raid controller.
Click to expand...

I haven't heard of ICH9R having a limitation to only even numbers of drives on RAID 0, but I have not tried it myself and my X38+ICH9R motherboard is not arriving until Wednesday for me to test it.

I guess we'll wait and see if someone shows up and says they are using 3 or 5 drives in RAID 0 on the controller.
 
i believe RAID 5 requires odd, which is RAID 10 (or 0+1) but with a failsafe so to speak. but thanks for asking that question, ive been wondering about that myself
 
i run 3 36 gb raptors on silicon image 3114 controller.
 
RAID 0 is 2 drives or any number greater, RAID 5 is 3 drives or greater. Any recent built in Intel RAID should be fine for 2 - 4 drives in RAID 0. If I were going more drives or RAID 5, I would get an addin card. No matter if it is an odd or even number of drives once you exceed the minimum. A mirrored array always has to have an even amount, an array based on striping or parity does not matter. Because of mechanical limitations, there more drives you add to RAID 0, the less return in increased speed you will get. I wouldn't bother with more than 2, 3 at the most. With RAID 5, the more drives you have, the more that can fail without data loss. With RAID 0 if any fail you're screwed. I use 2, nice speed increase. I keep full backups of course.
 
xxEIEIOxx said:
With RAID 5, the more drives you have, the more that can fail without data loss.
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Er.. it's my understanding that RAID 5 can only withstand the loss of one drive, and if another fails simultaneously or during rebuild, the array is lost. RAID 6 can withstand 2 simultaneous failures or a failure during rebuild...
 
NKDietrich said:
Er.. it's my understanding that RAID 5 can only withstand the loss of one drive, and if another fails simultaneously or during rebuild, the array is lost. RAID 6 can withstand 2 simultaneous failures or a failure during rebuild...
Click to expand...

You are correct. I thought that it duplicated the parity with more drives. I see I was mistaken. That being the case, I wouldn't use more than 3 drives. Actually, that being the case, I wouldn't use it at all. RAID 10 would be faster.
 
So could the reason Gigabyte listed Raid 0 as needing even number of drives in the manual for the GA-X48-DQ6 because of a limitation of the Intel ICH9R controller? I can't call support until Monday.
 
Another thought. If the Intel ICH9R controller does indeed need even number of drives, and supports a max partition of 2TB, here is what I could do.

1. As of now, the three WD 640GB drives I have come to 1,788GB (after formating). I could buy a forth and partition in it enough to equal 2,000GB even. And then use the rest for the OS and what now. However, first, could this be done? And would doing this affect the overall read/write speeds of the raid0? After all, three drives would be running at their full size and the forth would be using like 1/4 of it.

2. Return the three WD 640GB drives and buy four 500GB. :(

Any thoughts?
 
Seraphic said:
Another thought. If the Intel ICH9R controller does indeed need even number of drives, and supports a max partition of 2TB, here is what I could do.

1. As of now, the three WD 640GB drives I have come to 1,788GB (after formating). I could buy a forth and partition in it enough to equal 2,000GB even. And then use the rest for the OS and what now. However, first, could this be done? And would doing this affect the overall read/write speeds of the raid0? After all, three drives would be running at their full size and the forth would be using like 1/4 of it.

2. Return the three WD 640GB drives and buy four 500GB. :(

Any thoughts?
Click to expand...

Stick with the 2 640s. 4 would not be much faster, and 2 of those 640s would probably be faster than 4 500s.
 
xxEIEIOxx said:
You are correct. I thought that it duplicated the parity with more drives. I see I was mistaken. That being the case, I wouldn't use more than 3 drives. Actually, that being the case, I wouldn't use it at all. RAID 10 would be faster.
Click to expand...

RAID 10 looses half of your possible space though; for medium-sized arrays (5-10 disks I'd say) RAID 6 with a good controller, while having slightly less performance, will yield more available space than RAID 10, with enough security to last you through pretty much anything.

RAID 10 is awesome, if you're in an environment where individual drive space means almost nothing and you have many (read: dozens) of available hard drives. It really isn't economically worthwhile to have a 4-10 drive RAID 10 array, unless you're in conditions where you HAVE to know half of your hard drives can fail without incident.

/my $0.02
 
djBon2112 said:
RAID 10 looses half of your possible space though; for medium-sized arrays (5-10 disks I'd say) RAID 6 with a good controller, while having slightly less performance, will yield more available space than RAID 10, with enough security to last you through pretty much anything.

RAID 10 is awesome, if you're in an environment where individual drive space means almost nothing and you have many (read: dozens) of available hard drives. It really isn't economically worthwhile to have a 4-10 drive RAID 10 array, unless you're in conditions where you HAVE to know half of your hard drives can fail without incident.

/my $0.02
Click to expand...

For a business machine I would agree. For personal use, I would go with the 10. Drives are cheap. A good RAID 6 controller is not. I can use my onboard controller for 10. I would prefer something better, but money being a factor... sure I'd love a high end controller with RAID 6, some 15,000 rpm SCSI drives, dual quad CPUs, 16GB or RAM, quad SLI, a couples of pizzas, a keg of beer, :D
 
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