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Re: Filesystem returned to state of six months ago after fsck



On Mon, 2 Feb 2004, Nigel Metheringham wrote:

> [Copy to list - original accidently only sent to Boris]
> 
> On Sat, 2004-01-31 at 06:19, Boris Lenhard wrote:
> > Recently our sysadm accidentally powercycled our server (RedHat8)
> > after 198 days of uptime, and upon boot it insisted on checking one
> > partition (/dev/sda7) in our RAID. When it was done, the files were in
> > the state of August 23 last year, with anything newer either gone or
> > invisible. I guess something went wrong with journaling data. What can
> > I do to restore the current state (except restore from backup, which
> > is an unfavorable option on Saturday morning) ?.
> 
> This really can't be an ext3 fault.
> 
> It sounds more like a disk went offline in a RAID1 pair and then the
> disks swapped over on the restart (or the disk that been offline came
> online and the other disk was synced to it).  If you have 2 (sets of) 
> disks running in the current RAID set and they are synced I'd say you
> need your backups.   Otherwise its a case of working out how to get the
> right half of the RAID1 set up and then fixing from there.

It's also possible that there was a doublly mounted filesystem. For example,
/dev/sda7 was mounted as /var/ on top of an already mounted /dev/md6. Processes
have the namespace of /dev/sda7 and all the new data gets written there. When
the system reboots the raid1 array is unpinned and reconstructed, and possibly
mounted only once (/dev/sda7 may or may not be mounted), and presto, once the
reconstruction finishes you have your original data.

I've actually seen this happen :\

I'd be interested if you are able to prove or disprove this theory based upon
a previous copy of /etc/mtab and/or /proc/mounts and/or /proc/mdstat

Regards,

Matthew Galgoci

-- 
Matthew Galgoci
System Administrator
Red Hat, Inc
919.754.3700 x44155




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