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little_bob Retired Dev
Joined: 27 Jul 2004 Posts: 34
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Posted: Thu Sep 27, 2012 7:38 pm Post subject: sw raid 1 / wrong "/" after disc repair [solved] |
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hello community,
i am using 2 crucial 128gb discs in a sw raid 1 (with meta 0.9) on a asus p8b ws. the discs are connected to the two 6gb sata ports (port1 and port2). cause of a firmware bug i was forced to run my system for some days with the disc on port 2. i had plugged of the disc on port 1 for checking. i fixed the bug with a firmware update on both disc and plugged in the disc on port 1 back again.
when the system now come up i see in /proc/mdstat
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wooki ~ # cat /proc/mdstat
Personalities : [raid1]
md127 : active raid1 sdb3[1]
122834176 blocks [2/1] [_U]
md1 : active raid1 sda1[0] sdb1[1]
102336 blocks [2/2] [UU]
md3 : active raid1 sda3[0]
122834176 blocks [2/1] [U_]
unused devices: <none>
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md1 is ok.
md3 is broken and running with the old data from the disc which was not in the system for some days.
md127 is wrong but has the actual data i need.
mdadm examine shows for /dev/sda3
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wooki ~ # mdadm --examine /dev/sda3
/dev/sda3:
Magic : a92b4efc
Version : 0.90.00
UUID : b2406504:81284d9b:78a9b883:5f5f67d5
Creation Time : Thu Jan 12 16:05:31 2012
Raid Level : raid1
Used Dev Size : 122834176 (117.14 GiB 125.78 GB)
Array Size : 122834176 (117.14 GiB 125.78 GB)
Raid Devices : 2
Total Devices : 1
Preferred Minor : 3
Update Time : Thu Sep 27 19:24:02 2012
State : clean
Active Devices : 1
Working Devices : 1
Failed Devices : 1
Spare Devices : 0
Checksum : 5b7a591b - correct
Events : 761467
Number Major Minor RaidDevice State
this 0 8 3 0 active sync /dev/sda3
0 0 8 3 0 active sync /dev/sda3
1 1 0 0 1 faulty removed
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mdadm exmaine for /dev/sdb3 show
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wooki ~ # mdadm --examine /dev/sdb3
/dev/sdb3:
Magic : a92b4efc
Version : 0.90.00
UUID : b2406504:81284d9b:78a9b883:5f5f67d5
Creation Time : Thu Jan 12 16:05:31 2012
Raid Level : raid1
Used Dev Size : 122834176 (117.14 GiB 125.78 GB)
Array Size : 122834176 (117.14 GiB 125.78 GB)
Raid Devices : 2
Total Devices : 1
Preferred Minor : 3
Update Time : Wed Sep 26 13:53:21 2012
State : clean
Active Devices : 1
Working Devices : 1
Failed Devices : 0
Spare Devices : 0
Checksum : 5b64ebbc - correct
Events : 112460
Number Major Minor RaidDevice State
this 1 8 3 1 active sync /dev/sda3
0 0 0 0 0 removed
1 1 8 3 1 active sync /dev/sda3
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i can see that sda3 and sdb3 have the same uuid. how come?
/etc/mdadm.conf
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ARRAY /dev/md/3_0 metadata=0.90 UUID=b2406504:81284d9b:78a9b883:5f5f67d5
ARRAY /dev/md/1_0 metadata=0.90 UUID=cb91b603:9860658e:78a9b883:5f5f67d5
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i am not sure how to fix this.
someone has a tip?
best regards
Last edited by little_bob on Sun Sep 30, 2012 11:57 am; edited 1 time in total |
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NeddySeagoon Administrator
Joined: 05 Jul 2003 Posts: 54236 Location: 56N 3W
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Posted: Thu Sep 27, 2012 8:43 pm Post subject: |
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little_bob,
The two UUIDs are the same as they both refer to the same raid.
Code: | $ sudo mdadm -E /dev/sd[abcd]1 | grep UUID
UUID : 9392926d:64086e7a:86638283:4138a597
UUID : 9392926d:64086e7a:86638283:4138a597
UUID : 9392926d:64086e7a:86638283:4138a597
UUID : 9392926d:64086e7a:86638283:4138a597 | is from my 4 spindle raid1 /boot
You need to fail then remove the old partition from /dev/md3, so its back in degraded mode on one drive.
Then zero the raid superblock and add the partition to the /dev/md3 raid set.
Zeroing the superblock on the partition is destructive.
The problem is that the old drive has not failed, it was just dropped out of the raid, so it no longer holds a mirror of data, but its a valid degraded raid set on its own, so mdadm has started it as its own raid set.
Whe you add the 'replacement' partition, the raid set will rebuild. Watch /proc/mdstat _________________ Regards,
NeddySeagoon
Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail. |
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little_bob Retired Dev
Joined: 27 Jul 2004 Posts: 34
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Posted: Sat Sep 29, 2012 6:55 pm Post subject: |
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hello NeddySeagoon,
thank you for the infos.
"/" is on the active but "old" disk /dev/sda3 from /dev/md3.
i have stopped the wrong raid /dev/md127 (which has the actual data on /dev/sdb3). no problem.
then i tried to set the raid /dev/md3 to fail but as this raid holds my "/" it is busy.
Code: | wooki ~ # mdadm -f /dev/md3 /dev/sda3
mdadm: set device faulty failed for /dev/sda3: Device or resource busy
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i guess that would be no problem if the running /dev/md3 would be using /dev/sdb3 and not /dev/sda3.
is there a way to tell the system to use /dev/sdb3 instead of /dev/sda3 at boot time?
best regards |
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NeddySeagoon Administrator
Joined: 05 Jul 2003 Posts: 54236 Location: 56N 3W
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Posted: Sat Sep 29, 2012 7:01 pm Post subject: |
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little_bob,
root=/dev/md127 in grub.conf and in /etc/fstab, not the /dev/md3 you have thee currently _________________ Regards,
NeddySeagoon
Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail. |
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little_bob Retired Dev
Joined: 27 Jul 2004 Posts: 34
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Posted: Sat Sep 29, 2012 9:23 pm Post subject: |
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after a longer irc session with you (NeddySeagoon) it is solved #
thank you very much for the help and the time. |
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little_bob Retired Dev
Joined: 27 Jul 2004 Posts: 34
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Posted: Sun Sep 30, 2012 11:54 am Post subject: |
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hi community,
after the forum runs stable again i will describe formal what i have done to fix this.
- boot from usb stick with live dvd
- create md devices md1, md3 (with sdb3 and missing) and md127 (with sda3 and missing)
- mount md1 and adjust grub.conf (boot again from md3)
- mount md127 and check if it is old content (it was)
- mount md3 and check if it is actual content (it was)
- stop md127 and remove sda3 from it
- zero superblock on sda3
- add sda3 to md3
- observe /proc/mdstat and wait until recovery is finished
- reboot and check content
description i used for handling sw raid:
http://www.gentoo.org/doc/en/gentoo-x86+raid+lvm2-quickinstall.xml
http://en.wikipedia.org/wiki/Mdadm
there are also examples for commands. |
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NeddySeagoon Administrator
Joined: 05 Jul 2003 Posts: 54236 Location: 56N 3W
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Posted: Sun Sep 30, 2012 5:02 pm Post subject: |
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little_bob,
Thank you for sharing the solution. _________________ Regards,
NeddySeagoon
Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail. |
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