On Jun 23, 2013, at 4:24 PM, Eric Sandeen wrote: > 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 I'll try it and let you know. Should be interesting. - aurf _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
