On 6/23/13 5:55 PM, Dave Chinner wrote: > On Fri, Jun 21, 2013 at 10:30:31PM -0700, aurfalien wrote: >> Hi all, >> >> So I have an XFS file system within LVM which has an external log. >> >> My mount option in FSTAB is; >> >> /dev/vg_spock_data/lv_data /data xfs logdev=/dev/sdc1,nobarrier,logbufs=8,noatime,nodiratime 1 1 >> >> All is well no issues and very fast. >> >> Now I'd like to snapshot this bad boy and then run rsnapshot to create a few days backup. > > You need to snapshot the log device as well. > > But that is problematic in that you need to snapshot it at the same > time you snapshot the data volume. Hence yo'd have to do: > > # xfs_freeze -f <filesystem> > # <snapshot data volume> > # <snapshot log volume> > # xfs_freeze -u <filesystem> > > And now you can mount the snapshot with: > > # mount /dev/vg_spock_data/datasnapshot /snapshot -o nouuid,ro,logdev=/dev/vg_spock_log/logsnapshot > > If you can't snapshot the log device, then you can't snapshot the > filesystem. Yet another reason for using internal logs... Hm, given that freezing the fs makes the log (almost) completely clean, I wonder if he could mount with /dev/zero (or a loopback 0-filled file) to get at the snapshot, especially since it's being mounted RO. Should be safe & consistent, no? i.e. truncate --size=2g logfile (or however big it needs to be) losetup /dev/loop0 logfile mount /dev/vg_anette_data/datasnapshot /snapshot -o logdev=/dev/loop0,nouuid,ro -Eric > Cheers, > > Dave. > _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
