Hello list, Phil,
I read your advice in the text below and it seems very reasonable. I
want to do a test to see if the data is readable and this is what I
did with the live distro:
mdadm -A /dev/md13 /dev/sdb2 /dev/sdc2
and then mdadm said:
mdadm: can not open device /dev/sdb2: device or resource busy
mdadm: /dev/sdb2 has no superblock - assembly aborted
I don't know if these errors are related - i.e., if there is no
superblock is that the busy resource in the first message? And if the
superblock is absent can I put it back or somehow recreate it?
Dave
From: Phil Turmel <philip@xxxxxxxxxx>
To: Dave Stevens <geek@xxxxxxxxxxxx>, linux-raid@xxxxxxxxxxxxxxx
Subject: Re: two raid issues
Date: Sun, 08 Mar 2015 09:52:04 -0400
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101
Thunderbird/31.5.0
Good morning Dave,
On 03/07/2015 05:42 PM, Dave Stevens wrote:
Hello the raid list,
I have inherited a server set up by people who are no longer around. It
worked fine until recently and then after a routine update refused to
boot. I've got the machine in my office and have been examining the
problem, or rather problems, I think there are two.
Three, at least.
First, the bootable partition on /dev/sda1 won't successfully boot to a
xen kernel, kernel version is 2.6.18.something-xen. The intent is to
boot to a raid-10 array of four 750GB drives, each partitioned into a
small and a large partition as detailed below.
Boot proceeds normally according to on-screen messages until this:
md: md0: raid array is not clean -- starting background reconstruction
raid10: not enough operational mirrors for md0
md: pers -> () failed
Yup. Degraded to the point of not running.
Immediately after these messages is another stating that an attempt has
been made to kill init, kernel panic and reboot.
No way to pivot to your root filesystem, so your initramfs gives up.
Depending on the distro, it may be possible to pass a kernel command
line option to drop into a repair shell at that point.
I've tried to give these messages verbatim but have no way (I think) to
reproduce them other than manually.
Repair shell, if available.
So at first I looked around, read through the wiki and found advice to
NOT write anything to the array, which seems reasonable. I looked at a
live microknoppix distro called runtime live that gave me a command
shell to run the examine command with the output below:
LiveCD boot is good, and the following report is very detailed, thanks:
/dev/sda2:
Magic : a92b4efc
Version : 0.90.00
UUID : a9bde90a:77abaef6:6c6fe013:77d6cdaf
Creation Time : Sun Nov 29 15:33:50 2009
Raid Level : raid10
Used Dev Size : 732467456 (698.54 GiB 750.05 GB)
Array Size : 1464934912 (1397.07 GiB 1500.09 GB)
Raid Devices : 4
Total Devices : 3
Preferred Minor : 0
Update Time : Wed Feb 18 19:28:22 2015
State : active
Active Devices : 2
Working Devices : 2
Failed Devices : 2
Spare Devices : 0
Checksum : 7c76593b - correct
Events : 32945477
This is important: ^^^^^^^^
Layout : near=2
Chunk Size : 256K
Number Major Minor RaidDevice State
this 0 8 2 0 active sync /dev/sda2
0 0 8 2 0 active sync /dev/sda2
1 1 0 0 1 active sync
2 2 8 34 2 active sync /dev/sdc2
3 3 0 0 3 faulty removed
/dev/sdb2:
Magic : a92b4efc
Version : 0.90.00
UUID : a9bde90a:77abaef6:6c6fe013:77d6cdaf
Creation Time : Sun Nov 29 15:33:50 2009
Raid Level : raid10
Used Dev Size : 732467456 (698.54 GiB 750.05 GB)
Array Size : 1464934912 (1397.07 GiB 1500.09 GB)
Raid Devices : 4
Total Devices : 3
Preferred Minor : 0
Update Time : Sat Nov 22 13:18:12 2014
State : clean
Active Devices : 3
Working Devices : 3
Failed Devices : 1
Spare Devices : 0
Checksum : 7d850ca4 - correct
Events : 32945477
With this: ^^^^^^^^
Layout : near=2
Chunk Size : 256K
Number Major Minor RaidDevice State
this 1 8 18 1 active sync /dev/sdb2
0 0 8 2 0 active sync /dev/sda2
1 1 8 18 1 active sync /dev/sdb2
2 2 8 34 2 active sync /dev/sdc2
3 3 0 0 3 faulty removed
/dev/sdc2:
Magic : a92b4efc
Version : 0.90.00
UUID : a9bde90a:77abaef6:6c6fe013:77d6cdaf
Creation Time : Sun Nov 29 15:33:50 2009
Raid Level : raid10
Used Dev Size : 732467456 (698.54 GiB 750.05 GB)
Array Size : 1464934912 (1397.07 GiB 1500.09 GB)
Raid Devices : 4
Total Devices : 3
Preferred Minor : 0
Update Time : Wed Feb 18 19:30:13 2015
State : active
Active Devices : 1
Working Devices : 1
Failed Devices : 2
Spare Devices : 0
Checksum : 7c7659de - correct
Events : 32945479
And this: ^^^^^^^^
Layout : near=2
Chunk Size : 256K
Number Major Minor RaidDevice State
this 2 8 34 2 active sync /dev/sdc2
0 0 0 0 0 removed
1 1 0 0 1 faulty removed
2 2 8 34 2 active sync /dev/sdc2
3 3 0 0 3 faulty removed
/dev/sdd2:
Magic : a92b4efc
Version : 0.90.00
UUID : a9bde90a:77abaef6:6c6fe013:77d6cdaf
Creation Time : Sun Nov 29 15:33:50 2009
Raid Level : raid10
Used Dev Size : 732467456 (698.54 GiB 750.05 GB)
Array Size : 1464934912 (1397.07 GiB 1500.09 GB)
Raid Devices : 4
Total Devices : 5
Preferred Minor : 0
Update Time : Wed Sep 4 07:51:50 2013
State : active
Active Devices : 4
Working Devices : 5
Failed Devices : 0
Spare Devices : 1
Checksum : 77c1a3a7 - correct
Events : 53
Whoa! ^^^^
Layout : near=2
Chunk Size : 256K
Number Major Minor RaidDevice State
this 3 8 50 3 active sync /dev/sdd2
0 0 8 2 0 active sync /dev/sda2
1 1 8 18 1 active sync /dev/sdb2
2 2 8 34 2 active sync /dev/sdc2
3 3 8 50 3 active sync /dev/sdd2
4 4 8 66 4 spare /dev/sde2
/dev/sde2:
Magic : a92b4efc
Version : 0.90.00
UUID : a9bde90a:77abaef6:6c6fe013:77d6cdaf
Creation Time : Sun Nov 29 15:33:50 2009
Raid Level : raid10
Used Dev Size : 732467456 (698.54 GiB 750.05 GB)
Array Size : 1464934912 (1397.07 GiB 1500.09 GB)
Raid Devices : 4
Total Devices : 5
Preferred Minor : 0
Update Time : Sun Sep 8 13:25:42 2013
State : clean
Active Devices : 4
Working Devices : 4
Failed Devices : 0
Spare Devices : 0
Checksum : 77c775be - correct
Events : 7934
And Whoa again! ^^^^^^
Layout : near=2
Chunk Size : 256K
Number Major Minor RaidDevice State
this 3 8 66 3 active sync /dev/sde2
0 0 8 2 0 active sync /dev/sda2
1 1 8 18 1 active sync /dev/sdb2
2 2 8 34 2 active sync /dev/sdc2
3 3 8 66 3 active sync /dev/sde2
This makes sense to me as far as it goes but I don't see what to do
next. As I understand it the four partitions from sda2 to sdd2 would
form the array with sde as hot spare. It has been my assumption that if
a drive failed that sde would sync and take over. I don't know if this
is in fact the case and don't see a path forward. Of course the backups
are inadequate.
Based on the events and update timestamps, sdd died sometime around Wed
Sep 4 07:51:50 2013, at which point sde stepped in. It too failed
shortly after ~ Sun Sep 8 13:25:42 2013. You then ran degraded for over
a year until sdb also failed ~ Sat Nov 22 13:18:12 2014. You were then
running doubly-degraded (luckily on non-adjacent members) until this Feb
14 when sda was booted out. Leaving only one running drive.
{ I wouldn't keep such people around, either. }
Your best bet is to force assembly of the last two working drives to get
the system running, then take an immediate backup of all critical files.
Do the forced assembly with the livecd, then do a clean shutdown. You
should then be able to boot the original OS and take your backup.
Then you need to completely rebuild your system with proper log
monitoring, array monitoring, and verification of your drives.
Phil
--
"As long as politics is the shadow cast on society by big business,
the attenuation of the shadow will not change the substance."
-- John Dewey
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