Heres an oddity - Just built a server with 15 external disks over 2 SAS
channels and I've noticed that the kernel is saying it's RAID5 rather than
RAID6 ...
Hard to explain what I mean in words, but:
bertha:~# cat /proc/mdstat
Personalities : [raid0] [raid1] [raid6] [raid5] [raid4]
md9 : active raid6 sdh1[14] sdo1[13] sdg1[12] sdn1[11] sdf1[10] sdm1[9]
sde1[8] sdl1[7] sdd1[6] sdk1[5] sdc1[4] sdj1[3] sdb1[2] sdi1[1] sda1[0]
6341993216 blocks level 6, 128k chunk, algorithm 2 [15/15]
[UUUUUUUUUUUUUUU]
md1 : active raid1 sdq1[1] sdp1[0]
497856 blocks [2/2] [UU]
md2 : active raid1 sdq2[1] sdp2[0]
2000000 blocks [2/2] [UU]
md3 : active raid1 sdq3[1] sdp3[0]
2000000 blocks [2/2] [UU]
md5 : active raid1 sdq5[1] sdp5[0]
73240192 blocks [2/2] [UU]
md6 : active raid1 sdq6[1] sdp6[0]
78509504 blocks [2/2] [UU]
unused devices: <none>
and:
bertha:~# ps ax | grep raid
1022 ? S< 0:00 [md6_raid1]
1026 ? S< 0:00 [md5_raid1]
1030 ? S< 0:00 [md3_raid1]
1034 ? S< 0:00 [md2_raid1]
1038 ? S< 0:06 [md1_raid1]
1747 ? S< 724:25 [md9_raid5]
Note the raid5 at the bottom, even though /proc/mdstat says it's raid-6.
It was created with:
mdadm --create /dev/md9 -n15 -l6 --chunk=128 \
/dev/sda1 /dev/sdi1 \
/dev/sdb1 /dev/sdj1 \
/dev/sdc1 /dev/sdk1 \
/dev/sdd1 /dev/sdl1 \
/dev/sde1 /dev/sdm1 \
/dev/sdf1 /dev/sdn1 \
/dev/sdg1 /dev/sdo1 \
/dev/sdh1
Is this right? I've been thrashing it all week and just notice this. On
other servers I have using RAID-6, I get what I expect in the 'ps' output.
I was just about to start removing disks from it to test rebuild, etc...
Now not so sure!
It's kernel 2.6.18 and
mdadm - v1.9.0 - 04 February 2005
(Debian Sarge)
Finally:
bertha:~# mdadm --detail /dev/md9
/dev/md9:
Version : 00.90.03
Creation Time : Tue Oct 17 14:35:06 2006
Raid Level : raid6
Array Size : 6341993216 (6048.20 GiB 6494.20 GB)
Device Size : 487845632 (465.25 GiB 499.55 GB)
Raid Devices : 15
Total Devices : 15
Preferred Minor : 9
Persistence : Superblock is persistent
Update Time : Tue Oct 24 06:26:03 2006
State : clean
Active Devices : 15
Working Devices : 15
Failed Devices : 0
Spare Devices : 0
Chunk Size : 128K
UUID : c1a3973d:c46b7356:402fd93c:9778e5a5
Events : 0.8
Number Major Minor RaidDevice State
0 8 1 0 active sync /dev/sda1
1 8 129 1 active sync /dev/sdi1
2 8 17 2 active sync /dev/sdb1
3 8 145 3 active sync /dev/sdj1
4 8 33 4 active sync /dev/sdc1
5 8 161 5 active sync /dev/sdk1
6 8 49 6 active sync /dev/sdd1
7 8 177 7 active sync /dev/sdl1
8 8 65 8 active sync /dev/sde1
9 8 193 9 active sync /dev/sdm1
10 8 81 10 active sync /dev/sdf1
11 8 209 11 active sync /dev/sdn1
12 8 97 12 active sync /dev/sdg1
13 8 225 13 active sync /dev/sdo1
14 8 113 14 active sync /dev/sdh1
Gordon
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