On Wed, 2013-11-13 at 17:36 +0100, Guido Winkelmann wrote: > Hi, > > We are having some trouble with one of our fileservers using XFS (on linux). > Yesterday, one of the external RAIDs on the server failed. Of course, it is > unavoidable that some data would get lost from the fileserver in such an > event, however, we lost a lot more files than would seem reasonable. In > particular, we lost a number of files that had not been written to (but had > been been read from, in some cases) in several weeks. > > The data loss manifested itself through files being truncated to length 0 or > to some other size short of what they should be. (We happen to have an > external database that keeps track of that.) > > The fileserver is based on CentOS 6.3 with kernel version > 2.6.32-279.9.1.el6.x86_64. It has got several external RAIDs in the 100 TB > range, connected via FibreChannel. > > In case it matters: The server's primary role is as a samba server servicing a > large number of Windows XP and Windows 7 machines. > > We had already been trying to reduce the possible impact of a hardware failure > by setting a few tunables in /etc/sysctl.conf to try and make the kernel not > keep dirty buffers around too long: > > vm.dirty_background_bytes = 536870912 > vm.dirty_bytes = 134217728 > vm.dirty_writeback_centisecs = 500 > vm.dirty_expire_centisecs = 3000 > > and by issuing a sync from cron every 15 minutes: > > 0,15,30,45 * * * * /bin/sync > > Unfortunately, I seem to be unable so far to reproduce the issue on a smaller > system - and I cannot exactly just walk up to the in-production fileserver and > rip out yet another array just to see what happens... > > This leaves me with a few questions: > > Why did we lose so much data through the crash? > > Why did not even a sync every 15 minutes prevent further damage? > > What can we do to prevent this from happening again in the future? > > Regards, > > Guido Syncing won't protect you from hardware failures. Without more details about what happened to the external RAID and what you did to recover it's impossible to answer your question. -- Roger _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
