Re: mdadm and fsck

[Joey L <mjh2000@gmail.com>]

Thanks for the info and quick reply.

My /dev/md0 has rebuilt itself and is okay.

My /dev/md1 is gone after a reboot - and is no longer showing -

I get nothing when i run:

root@rider:~# mdadm --detail /dev/md1

mdadm: cannot open /dev/md1: No such file or directory

Questions for you:

1. How do I figure out which drive that made up /dev/md1  DRIVES: /dev/sdc or /dev/sdc1 and /dev/sdd or /dev/sdd1  is okay to be the master where I would rebuild the second ??

2. How do I "zero superblocks" a drive ?? I know how to fail, remove and add to a raid device.

3. Should I use /dev/sdd1 as the master ?? the system marked it as a spare before.

thanks

mjh

On Sat, Sep 17, 2011 at 4:39 PM, tv.debian@googlemail.com <tv.debian@googlemail.com> wrote:

17/09/2011 17:18, Joey L wrote:
> I have a broken raid1 drive set - i was able to fix 1 but the other raid
> still has issues.
> i have gone through the tutorials online to bring it back online but
> still unable to bring it back.
>
> Do i have to run fsck on the individual member drives ???

Short answer: NO ! You run fsck on raid volumes on which the (umounted)
file-system resides, that is "fsck /dev/md1".

>
> my /proc/mdstat looks like:
> Personalities : [raid1]
> md1 : active raid1 sdc1[0] sdd1[1](S)
>       976758841 blocks super 1.2 [2/1] [U_]
>
> md0 : active raid1 sda1[2] sdb1[1]
>       972654456 blocks super 1.2 [2/1] [_U]
>       [==========>..........]  recovery = 50.7% (493690944/972654456)
> finish=416.5min speed=19162K/sec
>
> my fstab is :
> # <file system> <mount point>   <type>  <options>       <dump>  <pass>
> proc            /proc           proc    defaults        0       0
> # / was on /dev/md0 during installation
> UUID=611258bc-4ace-4779-b44d-73ba1949f7db /               ext4
>  errors=remount-ro 0       1
> # swap was on /dev/md1 during installation
> UUID=f9dc126d-9593-475a-ab0e-b4126146d885 none            swap    sw
>          0       0
> /dev/scd0       /media/cdrom0   udf,iso9660 user,noauto     0       0
> /dev/fd0        /media/floppy0  auto    rw,user,noauto  0       0
> /dev/md1        /mnt/raid  ext4 rw        0       1
>
>
> my questions is :
> 1. how can i bring it back online.

Well, it depends, what did you try so far, did you "--run" it ? Is md1
not accessible as it is ? It should be even in degraded mode.
What does "mdadm --detail /dev/md1" and "mdadm --examine /dev/sdd1" say
? What's in your mdadm.conf ?

md0 is in recovery mode, leave it alone for a few hours (416/60) and see
how it goes.

> 2. what is the (S) mean ?

sdd1 is a spare. If you want to manually add it as a member of the
array, you can fail and remove it, zero superblocks, then add it back to
the raid. You should see the raid rebuilding right after.
As to why it is not automatically included in the array as a replacement
for the failed member when the array is run, I don't know.

> 3. how do i run fsck or other utility on ext4 filesystem ?
 > 4. do i run it on the raid1 device /dev/md0 or on the individual devices
> /dev/sda and /devsdb

Run fsck directly on the raid volume, file-system must not be mounted.
Unless you are running an old version of e2fsprogs ext4 support should
not be a problem.

> thanks
> mjh
>
>
>


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