Peter Rabbitson wrote:
After Tor Arne reported his success I figured I will simply fail/remove
sda3, scrape it clean, and will add it back. I zeroed superblocks
beforehand and also wrote zeros (dd if=/dev/zero) to the drives start
and end just to make sure everythign is off. After resync I am back at
square one - the offset of sda3 is different than everything else and
the array has one failed drive. If someone can shed some light I made
snapshots of the superblocks[1] alongside with the current output of
mdadm at http://rabbit.us/pool/md5_problem.tar.bz2.
Not sure if this is at all related to your problem, but one of the
things I tried was to shred all the old drives in the system that were
not going to be part of the array.
/dev/sda system (250GB) <-- shred
/dev/sdb home (250GB) <-- shred
/dev/sdc raid (750GB)
/dev/sdd raid (750GB)
/dev/sde raid (750GB)
/dev/sdf raid (750GB)
The reason I did this was because /dev/sda and /dev/sdb used to be part
of a RAID1 array, but were now used as system disk and home disk
respectively. I was afraid that mdadm would pick up on some of the
lingering RAID superblocks on those disks when reporting, so I shredded
them both using 'shred -n 1' and reinstalled.
Don't know if that affected anything at all for me, since the actual
problem was that I didn't wait for a full resync, but now you know :)
Tor Arne
[1] dd if=/dev/sdX3 of=sdX_sb count=<Data Offset> bs=512
Here is my system config:
root@Thesaurus:/arx/space/pool# fdisk -l /dev/sd[abcd]
Disk /dev/sda: 400.0 GB, 400088457216 bytes
255 heads, 63 sectors/track, 48641 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x00000000
Device Boot Start End Blocks Id System
/dev/sda1 1 7 56196 fd Linux raid
autodetect
/dev/sda2 8 507 4016250 fd Linux raid
autodetect
/dev/sda3 508 36407 288366750 83 Linux
/dev/sda4 36408 48641 98269605 83 Linux
Disk /dev/sdb: 320.0 GB, 320072933376 bytes
255 heads, 63 sectors/track, 38913 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x00000000
Device Boot Start End Blocks Id System
/dev/sdb1 1 7 56196 fd Linux raid
autodetect
/dev/sdb2 8 507 4016250 fd Linux raid
autodetect
/dev/sdb3 508 36407 288366750 83 Linux
/dev/sdb4 36408 38913 20129445 83 Linux
Disk /dev/sdc: 300.0 GB, 300090728448 bytes
255 heads, 63 sectors/track, 36483 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x00000000
Device Boot Start End Blocks Id System
/dev/sdc1 1 7 56196 fd Linux raid
autodetect
/dev/sdc2 8 507 4016250 fd Linux raid
autodetect
/dev/sdc3 508 36407 288366750 83 Linux
/dev/sdc4 36408 36483 610470 83 Linux
Disk /dev/sdd: 300.0 GB, 300090728448 bytes
255 heads, 63 sectors/track, 36483 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x00000000
Device Boot Start End Blocks Id System
/dev/sdd1 1 7 56196 fd Linux raid
autodetect
/dev/sdd2 8 507 4016250 fd Linux raid
autodetect
/dev/sdd3 508 36407 288366750 83 Linux
/dev/sdd4 36408 36483 610470 83 Linux
root@Thesaurus:/arx/space/pool#
root@Thesaurus:~# cat /proc/mdstat
Personalities : [raid0] [raid1] [raid10] [raid6] [raid5] [raid4]
md5 : active raid5 sda3[4] sdd3[3] sdc3[2] sdb3[1]
865081344 blocks super 1.1 level 5, 2048k chunk, algorithm 2 [4/4]
[UUUU]
md1 : active raid1 sdd1[3] sdc1[2] sdb1[1] sda1[0]
56128 blocks [4/4] [UUUU]
md10 : active raid10 sdd2[3] sdc2[2] sdb2[1] sda2[0]
5353472 blocks 1024K chunks 3 far-copies [4/4] [UUUU]
unused devices: <none>
root@Thesaurus:~#
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