On Thu, Jun 10, 2010 at 03:11:43PM -0700, Drew wrote:
> Actually No. If it is RAID-5 as you claim, then currently it is
> effectively a RAID-0.
>
> RAID-5 is Striping with Distributed Parity and requires a *minimum* of
> 3 disks. Two disks, regardless of how you got there, is considered
> a degraded state.
Sounds to me that you can still stripe and distribute parity with two
drives, only that parity will amount to mirroring, and it can still
tolerate a single drive failure. I got there in the usual way, creating
a RAID5 with --raid-devices=2.
--8<------8<------8<------8<------8<------8<------8<------8<------8<----
$ mdadm --detail /dev/md4
/dev/md4:
Version : 0.90
Creation Time : Thu Nov 27 15:48:58 2008
Raid Level : raid5
Array Size : 484391808 (461.95 GiB 496.02 GB)
Used Dev Size : 484391808 (461.95 GiB 496.02 GB)
Raid Devices : 2
Total Devices : 2
Preferred Minor : 4
Persistence : Superblock is persistent
Update Time : Thu Jun 10 15:16:45 2010
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 64K
UUID : 1da37f10:3c14071d:40784aba:8675d418
Events : 0.94324
Number Major Minor RaidDevice State
0 8 4 0 active sync /dev/sda4
1 8 20 1 active sync /dev/sdb4
--8<------8<------8<------8<------8<------8<------8<------8<------8<----
Gilad
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