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List:       evms-devel
Subject:    Re: [Evms-devel] Problems with Raid5 after upgrading to 2.4.0
From:       Mike Tran <mhtran () us ! ibm ! com>
Date:       2004-10-18 18:44:38
Message-ID: 1098125078.5234.23.camel () MIKETRAN ! austin ! ibm ! com
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On Mon, 2004-10-18 at 13:08, Dominik Westner wrote:
> Hi Mike,
> 
> thanks for pointing me to mdadm. This really helped me to reassemble 
> the raid.
> It's currently  running degraded, but recovering the 3rd disk.
> I tried to assemble the raid from my 3 devices but this did not work 
> with mdadm. When I just used 2 of them it worked.

You will have to wait for the resync to complete (ie. /proc/mdstat).

> 
> 
> I still don't know how this could happen. I made sure that the resync 
> finished before rebooting. (Actually there was a weekend between).
> 
> My raid5 setup contains 3 raid devices:
> /dev/hda4
> /dev/hde
> /dev/hdg

My guess is that the you had an I/O error on /dev/hdg and it was kicked
by the kernel md driver (1 faulty disk).  When you re-added the same
disk back to the array, it got kicked out again.  That's why you ended
up with 2 faulty disks.


> 
> Here are the details:
> 
> loki ~ # mdadm --detail /dev/md1
> /dev/md1:
>          Version : 00.90.01
>    Creation Time : Sat Mar  8 16:39:42 2003
>       Raid Level : raid5
>       Array Size : 78164992 (74.54 GiB 80.04 GB)
>      Device Size : 39082496 (37.27 GiB 40.02 GB)
>     Raid Devices : 3
>    Total Devices : 3
> Preferred Minor : 1
>      Persistence : Superblock is persistent
> 
>      Update Time : Mon Oct 18 20:47:51 2004
>            State : clean, degraded, recovering
>   Active Devices : 2
> Working Devices : 3
>   Failed Devices : 0
>    Spare Devices : 1
> 
>           Layout : left-symmetric
>       Chunk Size : 256K
> 
>   Rebuild Status : 1% complete
> 
>             UUID : 84695c0c:bb0c5b89:35b23d2d:105763b6
>           Events : 0.6656504
> 
>      Number   Major   Minor   RaidDevice State
>         0      33        0        0      active sync   /dev/hde
>         1       0        0        -      removed
>         2     253        3        2      active sync   
> /dev/evms/.nodes/hda4
> 
>         3      34        0        1      spare rebuilding   /dev/hdg
> 
> 
> Thanks again. Without your help I'd been lost, I never used anything 
> else than evms for my raid configuration.

OK. The raid5 array is resync-ing.  Check /proc/mdstat for /dev/md1
again to make sure that everything is ok.

> 
> I have one final question though. Can I use mdadm in parallel to evms? 
> (e.g. for monitoring).

You can use mdadm in conjunction with EVMS.  mdadm is command driven
user interface, thus you have to know what you are doing.  I have used
mdadm many times to re-create MD arrays, especially for raid5 array. 
When I use mdadm, I know exactly how many disks, chunk size, order of
the disks, missing if any, etc...

--
Regards,
Mike T.




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