On 04/06/13 17:06, Durval Menezes wrote:
Oliver,
What file system? LVM or direct on the MD device?
Sorry, should have mentioned this.
I have 4 1.5 TB sata drives, connected to the onboard sata controller.
I have made 1 GPT partition ontop of each drive and then made a raid5
array ontop of those devices:
md101 : active (read-only) raid5 sdd1[0] sde1[4] sdf1[1]
4395413760 blocks super 1.2 level 5, 256k chunk, algorithm 2
[4/3] [UU_U]
I then formatted /dev/md101 with ext4.
Tune2fs still happily runs on /dev/md101, but of course that doesn't
mean anything.
riley tmp # tune2fs -l /dev/md101
tune2fs 1.42 (29-Nov-2011)
Filesystem volume name: data01
Last mounted on: /tank/01
Filesystem UUID: 9c812d61-96ce-4b71-9763-b77e8b9618d1
Filesystem magic number: 0xEF53
Filesystem revision #: 1 (dynamic)
Filesystem features: has_journal ext_attr resize_inode dir_index
filetype extent flex_bg sparse_super large_file huge_file uninit_bg
dir_nlink extra_isize
Filesystem flags: signed_directory_hash
Default mount options: (none)
Filesystem state: not clean
Errors behavior: Continue
Filesystem OS type: Linux
Inode count: 274718720
Block count: 1098853440
Reserved block count: 0
Free blocks: 228693396
Free inodes: 274387775
First block: 0
Block size: 4096
Fragment size: 4096
Reserved GDT blocks: 762
Blocks per group: 32768
Fragments per group: 32768
Inodes per group: 8192
Inode blocks per group: 512
RAID stride: 64
RAID stripe width: 192
Flex block group size: 16
Filesystem created: Wed Apr 28 16:42:58 2010
Last mount time: Tue May 4 17:14:48 2010
Last write time: Sat Apr 6 11:45:57 2013
Mount count: 10
Maximum mount count: 32
Last checked: Wed Apr 28 16:42:58 2010
Check interval: 15552000 (6 months)
Next check after: Mon Oct 25 16:42:58 2010
Lifetime writes: 3591 GB
Reserved blocks uid: 0 (user root)
Reserved blocks gid: 0 (group root)
First inode: 11
Inode size: 256
Required extra isize: 28
Desired extra isize: 28
Journal inode: 8
First orphan inode: 17
Default directory hash: half_md4
Directory Hash Seed: f1248a94-5a6a-4e4a-af8a-68b019d13ef6
Journal backup: inode blocks
--
Durval.
On Apr 6, 2013 8:23 AM, "Oliver Schinagl" <oliver+list@xxxxxxxxxxx
<mailto:oliver%2Blist@xxxxxxxxxxx>> wrote:
Hi,
I've had a powerfailure today, to which my UPS responded nicely and
made my server shutdown normally. One would expect everything is
well, right? The array, as far as I know, was operating without
problems before the shutdown, all 4 devices where normally online.
mdadm sends me an e-mail if something is wrong, so does smartctl.
First thing I noticed that I had 2 (S) drives for /dev/md101. I thus
started examining things. First I thought that it was some mdadm
weirdness, where it failed to assemble the drive with all components.
mdadm -A /dev/md101 /dev/sd[cdef]1 failed and gave the same result.
Something was really wrong.
I checked and compared the output of mdadm --examine on all drives
(like -Evvvs below) and found that /dev/sdc1's events count was wrong.
/dev/sdf1 and /dev/sdd1 matched (and later sde1 too, but more on
that in a sec). So sdc1 may have been dropped from the array without
me knowing it, unlikely put possible. The odd thing is the huge
difference in event counts, but all four are marked as ACTIVE.
So then onto sde1; why was it failing on that. The gpt table was
completly gone. 00000. Gone. I used hexdump to examine the drive
further, and at 0x00041000 there was the mdraid table, as one would
expect. Good, so it looks like only the gpt has been wiped for some
misterious reason. Re-creating the gpt quickly revealed mdadm's
information was still correct (as can be seen below).
So ignore sdc1 and assemble the drive as is should be fine? Right? No.
mdadm -A /dev/md101 /dev/sd[def]1 worked without error.
I always do a fsck before and after a reboot (unless of course I
can't do the shutdown fsck) and verify /proc/mdadm after a boot. So
before mounting, as always, I tried to run fsck /dev/md101 -C -; but
that came up with tons of errors. I didn't fix anything and aborted.
And here we are now. I can't just copy the entire disk (1.5TB per
disk) and 'experiment', I don't have 4 spare disks. The first thing
I would want to try is is mdadm -A /dev/sd[cdf]1 --force (leave out
the possibly corrupted sde1) and see what that does.
All that said when I did the assemble with the 'guessed' 3 correct
drives. Did of course increase the events count. sdc1 of course
didn't partake in this. Assuming that it is in sync with the rest,
what is the worst that can happen? And does the --read-only flag
protect against it?
Linux riley 3.7.4-gentoo #2 SMP Tue Feb 5 16:20:59 CET 2013 x86_64
AMD Phenom(tm) II X4 905e Processor AuthenticAMD GNU/Linux
riley tmp # mdadm --version
mdadm - v3.1.4 - 31st August 2010
riley tmp # mdadm -Evvvvs
/dev/sdf1:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : 2becc012:2d317133:2447784c:__1aab300d
Name : riley:data01 (local to host riley)
Creation Time : Tue Apr 27 18:03:37 2010
Raid Level : raid5
Raid Devices : 4
Avail Dev Size : 2930276351 (1397.26 GiB 1500.30 GB)
Array Size : 8790827520 (4191.79 GiB 4500.90 GB)
Used Dev Size : 2930275840 (1397.26 GiB 1500.30 GB)
Data Offset : 272 sectors
Super Offset : 8 sectors
State : clean
Device UUID : 97877935:04c16c5f:0746cb98:__63bffb4c
Update Time : Sat Apr 6 11:46:03 2013
Checksum : b585717a - correct
Events : 512993
Layout : left-symmetric
Chunk Size : 256K
Device Role : Active device 1
Array State : AA.A ('A' == active, '.' == missing)
mdadm: No md superblock detected on /dev/sdf.
/dev/sde1:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : 2becc012:2d317133:2447784c:__1aab300d
Name : riley:data01 (local to host riley)
Creation Time : Tue Apr 27 18:03:37 2010
Raid Level : raid5
Raid Devices : 4
Avail Dev Size : 2930275847 (1397.26 GiB 1500.30 GB)
Array Size : 8790827520 (4191.79 GiB 4500.90 GB)
Used Dev Size : 2930275840 (1397.26 GiB 1500.30 GB)
Data Offset : 776 sectors
Super Offset : 8 sectors
State : clean
Device UUID : 3f48d5a8:e3ee47a1:23c8b895:__addd3dd0
Update Time : Sat Apr 6 11:46:03 2013
Checksum : eaec006b - correct
Events : 512993
Layout : left-symmetric
Chunk Size : 256K
Device Role : Active device 3
Array State : AA.A ('A' == active, '.' == missing)
mdadm: No md superblock detected on /dev/sde.
/dev/sdd1:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : 2becc012:2d317133:2447784c:__1aab300d
Name : riley:data01 (local to host riley)
Creation Time : Tue Apr 27 18:03:37 2010
Raid Level : raid5
Raid Devices : 4
Avail Dev Size : 2930276351 (1397.26 GiB 1500.30 GB)
Array Size : 8790827520 (4191.79 GiB 4500.90 GB)
Used Dev Size : 2930275840 (1397.26 GiB 1500.30 GB)
Data Offset : 272 sectors
Super Offset : 8 sectors
State : clean
Device UUID : 236f6c48:2a1bcf6b:a7d7d861:__53950637
Update Time : Sat Apr 6 11:46:03 2013
Checksum : 87f31abb - correct
Events : 512993
Layout : left-symmetric
Chunk Size : 256K
Device Role : Active device 0
Array State : AA.A ('A' == active, '.' == missing)
mdadm: No md superblock detected on /dev/sdd.
/dev/sdc1:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : 2becc012:2d317133:2447784c:__1aab300d
Name : riley:data01 (local to host riley)
Creation Time : Tue Apr 27 18:03:37 2010
Raid Level : raid5
Raid Devices : 4
Avail Dev Size : 2930276351 (1397.26 GiB 1500.30 GB)
Array Size : 8790827520 (4191.79 GiB 4500.90 GB)
Used Dev Size : 2930275840 (1397.26 GiB 1500.30 GB)
Data Offset : 272 sectors
Super Offset : 8 sectors
State : active
Device UUID : 3ce8e262:ad864aee:9055af9b:__6cbfd47f
Update Time : Sat Mar 16 20:20:47 2013
Checksum : a7686a57 - correct
Events : 180132
Layout : left-symmetric
Chunk Size : 256K
Device Role : Active device 2
Array State : AAAA ('A' == active, '.' == missing)
mdadm: No md superblock detected on /dev/sdc.
Before I assembled the array for the first time (mdadm -A /dev/md101
/dev/sdd1 /dev/sde1 /dev/sdf1), this is how it looked like:
So identical to the above, wtih the exception of the number of events.
riley tmp # mdadm --examine /dev/sde1
/dev/sde1:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : 2becc012:2d317133:2447784c:__1aab300d
Name : riley:data01 (local to host riley)
Creation Time : Tue Apr 27 18:03:37 2010
Raid Level : raid5
Raid Devices : 4
Avail Dev Size : 2930275847 (1397.26 GiB 1500.30 GB)
Array Size : 8790827520 (4191.79 GiB 4500.90 GB)
Used Dev Size : 2930275840 (1397.26 GiB 1500.30 GB)
Data Offset : 776 sectors
Super Offset : 8 sectors
State : clean
Device UUID : 3f48d5a8:e3ee47a1:23c8b895:__addd3dd0
Update Time : Sat Apr 6 09:44:30 2013
Checksum : eaebe3ea - correct
Events : 512989
Layout : left-symmetric
Chunk Size : 256K
Device Role : Active device 3
Array State : AA.A ('A' == active, '.' == missing)
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