RE: Should I Start Over?

Do you have the command you used to create the array the first time?

-----Original Message-----
From: linux-raid-owner@vger.kernel.org
[mailto:linux-raid-owner@vger.kernel.org] On Behalf Of Guy
Sent: Wednesday, July 07, 2004 9:40 AM
To: stephen@exitwound.org
Cc: linux-raid@vger.kernel.org
Subject: RE: Should I Start Over?

You did not use the "missing" keyword.  You just created a 3 disk array.  If
your array had 3 disks, you should have listed 2 of them and the "missing"
keyword for the third.  Why did you add a spare(hde1)?

I am guessing your array had 4 disks.  You should have done something like
this:
mdadm --create /dev/md0 --level=5 --raid-devices=4 /dev/hdg1 /dev/hdd1
/dev/hdc1 missing
Note the "--raid-devices=4" and "missing".

I think your data is gone.  At least 1/3 or 1/4 of it.

Which ever disk it is rebuilding to, has been trashed!
Stop the array and re-create it, but this time list the disk as missing.  Do
this command to determine which disk is being re-built:
cat /proc/mdadm
You must do this before the re-build is finished!

Guy



-----Original Message-----
From: linux-raid-owner@vger.kernel.org
[mailto:linux-raid-owner@vger.kernel.org] On Behalf Of Stephen Hargrove
Sent: Wednesday, July 07, 2004 9:24 AM
To: Luca Berra
Cc: linux-raid@vger.kernel.org
Subject: Re: Should I Start Over?

Luca Berra said:

you can try to see if you can read your data by recreating the array in
degraded mode, so it does not rebuild.

like:
mdadm --create /dev/md0 --level=5 /dev/hdc1 /dev/hdd1 missing
try substituting the word missing for each of the drives
and see if you can mount the filesystem
if you do find your data use:
mdadm /dev/md0 -a <the device you replaced with missing>
to have it added to the array again

Ok, I did the following:

# mdadm --create /dev/md0 --level=5 --raid-devices=3 /dev/hdg1 /dev/hdd1
/dev/hdc1
mdadm: array /dev/md0 started.
# mdadm /dev/md0 -a /dev/hde1
mdadm: hot added /dev/hde1
# mount /data
mount: wrong fs type, bad option, bad superblock on /dev/md0,
       or too many mounted file systems
# cat /proc/mdstat
Personalities : [raid5]
read_ahead 1024 sectors
md0 : active raid5 hde1[4] hdc1[3] hdd1[1] hdg1[0]
      240121472 blocks level 5, 64k chunk, algorithm 2 [3/2] [UU_]
      [>....................]  recovery =  0.2% (282348/120060736)
finish=2250.3min speed=884K/sec
unused devices: <none>

If I read your email correctly, I wasn't expecting this.  But I'm also
inexperienced enough to not really know what to expect.  All I know is
that I now have movement where, before, I had none.

So is this good or bad?  Is my data gone forever (I gave up on it a while
back, so if it's gone, it's gone)?

Thanks again, Luca.  You rock!

--
Steve
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