RAID 0

iKettles · 2 Apr 2008 at 11:26

I'm considering a RAID 0 setup with two Samsung Spinpoint 500GB drives. Obviously RAID 0 isn't redundant and if one drive fails you lose all the data. Is it possible to have a RAID 0 array but then have that array mirrored onto another drive?

HeX · 2 Apr 2008 at 11:31

Yes, but you'd need 4 x 500GB drives and you'd need to run RAID 0+1.

Delvis · 2 Apr 2008 at 12:04

As HeX said, you would need four drives in able to have a mirror of the first Raid 0

S_D · 3 Apr 2008 at 09:47

Raid 10 would be better than Raid 0+1. You can lose two drives with Raid 10 but only 1 with Raid 0+1..

Simon

rpstewart · 3 Apr 2008 at 10:31

S_D said:
Raid 10 would be better than Raid 0+1. You can lose two drives with Raid 10 but only 1 with Raid 0+1..

Simon

They can both in theory handle the loss of 2 disks but it's very specific which 2 disks. It's a total pain to get our head round but RAID0+1 can only lose 1 particular disk from a degraded set and still operate whereas RAID10 can survive the loss of one of 2 disks from a degraded array.

HeX · 3 Apr 2008 at 10:32

Yeah, but most mobo raid controlers don't do RAID 10

Usually just:

0
1
0+1
5
JBOD

S_D · 3 Apr 2008 at 11:28

rpstewart said:
They can both in theory handle the loss of 2 disks but it's very specific which 2 disks. It's a total pain to get our head round but RAID0+1 can only lose 1 particular disk from a degraded set and still operate whereas RAID10 can survive the loss of one of 2 disks from a degraded array.

You're right, of course, but with Raid 0+1 (a mirror of stripes) the odds of two disks failing from the same stripe set is a lot lower than the odds of two disks failing from a different mirror set in Raid 10 (a stripe of mirrors). Plus in Raid 0+1 as soon as you get a failed disk and lose a strip set, you're very likely to act then rather than continue until the other disk in the same set fails (which is irrelevant anyway as you've already lost that set's data.

It's a moot point anyway as a lot of MBs don't handle Raid 10 as Hex points out. I think the P5K deluxe (and other ICH9R boards?) does though...

Simon

rpstewart · 3 Apr 2008 at 12:38

S_D said:
You're right, of course, but with Raid 0+1 (a mirror of stripes) the odds of two disks failing from the same stripe set is a lot lower than the odds of two disks failing from a different mirror set in Raid 10 (a stripe of mirrors). Plus in Raid 0+1 as soon as you get a failed disk and lose a strip set, you're very likely to act then rather than continue until the other disk in the same set fails (which is irrelevant anyway as you've already lost that set's data.

That's a far better articulation of what I was trying to say than I managed.