Hi!
I'm trying to build a Linux RAID5 with four (4) 750GB disks, but not
matter what I do I end up with mdadm listing five (5) devices and
telling me that one of them is a spare, and another one is
failed/removed. I've been googling and reading HOWTOs for a week now,
but can't figure it out. Here's what I do:
monstre:~/buildroot # mdadm --create /dev/md0 --level=5 --raid-devices=4
/dev/sd[cdef]1
mdadm: /dev/sdc1 appears to contain an ext2fs file system
size=-2097251968K mtime=Wed Feb 27 00:26:57 2008
mdadm: /dev/sdc1 appears to be part of a raid array:
level=raid5 devices=4 ctime=Tue Feb 26 20:47:24 2008
mdadm: /dev/sdd1 appears to be part of a raid array:
level=raid5 devices=4 ctime=Tue Feb 26 20:47:24 2008
mdadm: /dev/sde1 appears to be part of a raid array:
level=raid5 devices=4 ctime=Tue Feb 26 20:47:24 2008
mdadm: /dev/sdf1 appears to contain an ext2fs file system
size=-1560381056K mtime=Wed Feb 27 00:26:57 2008
mdadm: /dev/sdf1 appears to be part of a raid array:
level=raid5 devices=4 ctime=Tue Feb 26 20:47:24 2008
Continue creating array? y
mdadm: array /dev/md0 started.
monstre:~/buildroot # cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md0 : active(auto-read-only) raid5 sdf1[4](S) sde1[2] sdd1[1] sdc1[0]
2197715712 blocks level 5, 64k chunk, algorithm 2 [4/3] [UUU_]
unused devices: <none>
monstre:~/buildroot # mdadm --detail /dev/md0
/dev/md0:
Version : 00.90.03
Creation Time : Tue Feb 26 20:57:46 2008
Raid Level : raid5
Array Size : 2197715712 (2095.91 GiB 2250.46 GB)
Used Dev Size : 732571904 (698.64 GiB 750.15 GB)
Raid Devices : 4
Total Devices : 4
Preferred Minor : 0
Persistence : Superblock is persistent
Update Time : Tue Feb 26 20:57:46 2008
State : clean, degraded
Active Devices : 3
Working Devices : 4
Failed Devices : 0
Spare Devices : 1
Layout : left-symmetric
Chunk Size : 64K
UUID : 8b498455:0ab45ac1:ebf26e3f:56a9fc2f
Events : 0.1
Number Major Minor RaidDevice State
0 8 33 0 active sync /dev/sdc1
1 8 49 1 active sync /dev/sdd1
2 8 65 2 active sync /dev/sde1
3 0 0 3 removed
4 8 81 - spare /dev/sdf1
monstre: # mdadm --examine /dev/sdd1
/dev/sdd1:
Magic : a92b4efc
Version : 00.90.00
UUID : a0186556:4ffb5a2a:822f8875:94ae7d2c
Creation Time : Sun Mar 2 22:52:53 2008
Raid Level : raid5
Used Dev Size : 732571904 (698.64 GiB 750.15 GB)
Array Size : 2197715712 (2095.91 GiB 2250.46 GB)
Raid Devices : 4
Total Devices : 4
Preferred Minor : 0
Update Time : Sun Mar 2 22:59:54 2008
State : clean
Active Devices : 3
Working Devices : 4
Failed Devices : 1
Spare Devices : 1
Checksum : 6b5e8442 - correct
Events : 0.22
Layout : left-symmetric
Chunk Size : 64K
Number Major Minor RaidDevice State
this 1 8 49 1 active sync /dev/sdd1
0 0 8 33 0 active sync /dev/sdc1
1 1 8 49 1 active sync /dev/sdd1
2 2 8 65 2 active sync /dev/sde1
3 3 0 0 3 faulty removed
4 4 8 81 4 spare /dev/sdf1
-------------------
So what i don't get is:
1. Why is mdadm --examine listing "3 3 0 0 3
faulty removed" and telling me I have a failed device?
2. Why is one of the actual disks (sdf) used as a spare, even though I
didn't ask for it?
Thanks for any tips or insights which may put me on the right track :)
Tor Arne
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