Hello :)
We have a computer based at the South Pole which has a degraded raid 5
array across 4 disks. One of the 4 HDD's mechanically failed but we have
bought the majority of the system back online except for the raid5
array. I am pretty sure that data on the remaining 3 partitions that
made up the raid5 array is intact - just confused. The reason I know
this is that just before we took the system down, the raid5 array
(mounted as /home) was still readable and writable even though
/proc/mdstat said:
*md2 : active raid5 hdd5[3] hdb5[2](F) hdc5[1] hda5[0](F)
844809600 blocks level 5, 128k chunk, algorithm 2 [4/2] [_U_U] *
When I tried to turn on the raid5 set /dev/md2 after replacing the
failed disk I saw the following errors:
Jul 8 12:35:28 planet kernel: [events: 0000003b]
Jul 8 12:35:28 planet kernel: [events: 00000000]
Jul 8 12:35:28 planet kernel: md: invalid raid superblock magic on hdc5
Jul 8 12:35:28 planet kernel: md: hdc5 has invalid sb, not importing!
Jul 8 12:35:28 planet kernel: md: could not import hdc5, trying to run
array nevertheless.
Jul 8 12:35:28 planet kernel: [events: 00000039]
Jul 8 12:35:28 planet kernel: [events: 0000003b]
Jul 8 12:35:28 planet kernel: md: autorun ...
Jul 8 12:35:28 planet kernel: md: considering hdd5 ...
Jul 8 12:35:28 planet kernel: md: adding hdd5 ...
Jul 8 12:35:28 planet kernel: md: adding hdb5 ...
Jul 8 12:35:28 planet kernel: md: adding hda5 ...
Jul 8 12:35:28 planet kernel: md: created md2
Jul 8 12:35:28 planet kernel: md: bind<hda5,1>
Jul 8 12:35:28 planet kernel: md: bind<hdb5,2>
Jul 8 12:35:28 planet kernel: md: bind<hdd5,3>
Jul 8 12:35:28 planet kernel: md: running: <hdd5><hdb5><hda5>
Jul 8 12:35:28 planet kernel: md: hdd5's event counter: 0000003b
Jul 8 12:35:28 planet kernel: md: hdb5's event counter: 00000039
Jul 8 12:35:28 planet kernel: md: hda5's event counter: 0000003b
Jul 8 12:35:28 planet kernel: md: superblock update time inconsistency
-- using the most recent one
*Jul 8 12:35:28 planet kernel: md: freshest: hdd5*
Jul 8 12:35:28 planet kernel: md: kicking non-fresh hdb5 from array!
Jul 8 12:35:28 planet kernel: md: unbind<hdb5,2>
Jul 8 12:35:28 planet kernel: md: export_rdev(hdb5)
Jul 8 12:35:28 planet kernel: md: device name has changed from hdc5 to
hda5 since last import!
Jul 8 12:35:28 planet kernel: md2: removing former faulty hda5!
Jul 8 12:35:28 planet kernel: md2: removing former faulty hdb5!
Jul 8 12:35:28 planet kernel: md: md2: raid array is not clean --
starting background reconstruction
Jul 8 12:35:28 planet kernel: md2: max total readahead window set to 1536k
Jul 8 12:35:28 planet kernel: md2: 3 data-disks, max readahead per
data-disk: 512k
Jul 8 12:35:28 planet kernel: raid5: device hdd5 operational as raid disk 3
Jul 8 12:35:28 planet kernel: raid5: device hda5 operational as raid disk 1
*Jul 8 12:35:28 planet kernel: raid5: not enough operational devices
for md2 (2/4 failed)*
Jul 8 12:35:28 planet kernel: RAID5 conf printout:
Jul 8 12:35:28 planet kernel: --- rd:4 wd:2 fd:2
Jul 8 12:35:28 planet kernel: disk 0, s:0, o:0, n:0 rd:0 us:1 dev:[dev
00:00]
Jul 8 12:35:28 planet kernel: disk 1, s:0, o:1, n:1 rd:1 us:1 dev:hda5
Jul 8 12:35:28 planet kernel: disk 2, s:0, o:0, n:2 rd:2 us:1 dev:[dev
00:00]
Jul 8 12:35:28 planet kernel: disk 3, s:0, o:1, n:3 rd:3 us:1 dev:hdd5
Jul 8 12:35:28 planet kernel: raid5: failed to run raid set md2
Jul 8 12:35:28 planet kernel: md: pers->run() failed ...
Jul 8 12:35:28 planet kernel: md :do_md_run() returned -22
Jul 8 12:35:28 planet kernel: md: md2 stopped.
Jul 8 12:35:28 planet kernel: md: unbind<hdd5,1>
Jul 8 12:35:28 planet kernel: md: export_rdev(hdd5)
Jul 8 12:35:28 planet kernel: md: unbind<hda5,0>
Jul 8 12:35:28 planet kernel: md: export_rdev(hda5)
Jul 8 12:35:28 planet kernel: md: ... autorun DONE.
I was googling for solutions and found the mdadm package and installed
it and tried:
/*[root@planet mdadm-1.12.0]# mdadm --assemble --force /dev/md2
/dev/hdd5 /dev/hda5 /dev/hdb5 /dev/hdc5
mdadm: no RAID superblock on /dev/hdc5
mdadm: /dev/hdc5 has no superblock - assembly aborted
*//dev/hdc is the new disk I have just installed to replace the failed
one (/dev/hda). I have parititioned it correctly and in fact one
partition on /dev/hdc1 is now happily part of another raid1 set on the
system so I know all is good with /dev/hdc
My current /proc/mdstat file looks like this (ie missing the raid5 set):
*
Personalities : [raid1] [raid5]
read_ahead 1024 sectors
md1 : active raid1 hdc2[0] hda2[1]
10241344 blocks [2/2] [UU]
md0 : active raid1 hdc1[0] hda1[1]
104320 blocks [2/2] [UU]
unused devices: <none>
*
Can anyone offer any suggestions as to how to get past the /*/dev/hdc5
has no superblock */message?
The data has all been backed up so as a last resort I will rebuild the
raid5 array from scratch but it would be nice to just reassemble it with
data intact as I am sure /dev/hdd5 /dev/hdb5 and /dev/hda5 are actually
all ok.
Many Thanks,
Melinda
/*
*/
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