On Sat, 2011-06-04 at 12:25 +0200, Martin Steigerwald wrote: > Hi! > > Now I thought about a way to safely backup a MySQL or other database - > without long service interruption: > > - Tell DB to turn itself into consistent state and freeze there > - sync / btrfs filesystem sync ; fsfreeze -f /mountpoint > - btrfs subvolume snapshot > - fsfreeze -u /mountpoint > - Tell DB to continue business as usual > > My questions are: > 2) Is the sync needed?
I'm not sure. In some cases it might not be: E.g. If the database uses fsync() to save the data when you tell it to go into a consistent state, there would be no need to have a separate sync. It shouldn't hurt, however. > 3) Is the fsfreeze needed at all? Does btrfs subvolume freeze the > filesystem prior to the snapshot? The manpage doesn´t tell it. The fsfreeze should not be needed. The btrfs subvolume snapshot command takes an atomic snapshot of the current subvolume state. -- Calvin Walton <[email protected]> -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
