[Voyage-linux] aufs: Sync to flash with our reboot ?

[Guido De Rosa]

2009/3/30 Kim-man 'Punky' TSE <punkytse at punknix.com>:

> I would try I could have some update on it later this week.  After I tested
> Guido's update and some of my additions.

Hi! Please always consider the last update:

http://bitbucket.org/gderosa/net-appliances/src/tip/voyage/etc/init.d/voyage-sync

Specifically, since rev9, some extra check has been added:

			# verify that $SYNC_DIR is actually mounted as a
			# $UNIONFS; otherwise, avoid dangerous over-writings
			# of $SYNCFS_ROOT/$SYNC_DIR
			if (mount | grep $SYNC_DIR | grep "type $UNIONFS" > /dev/null) ; then
				echo -n "  Sync'ing $SYNC_DIR to $SYNCFS_ROOT$SYNC_DIR ... "
				rsync $RSYNC_OPTS $SYNC_DIR $SYNCFS_ROOT/`dirname $SYNC_DIR`
				log_action_end_msg $?
			fi

Think about the following scenario:you've been using AUFS/UNIONFS for
a while and recently you have upgraded the kernel, but forgot to add
aufs support; you also have added to VOYAGE_SYNC_DIRS some directories
with important data; in this scenario, after the first reboot,
mounting of $SYNC_DIR fails, and you get stuck with old $SYNC_DIR
contained in your root partition. After another reboot, new data in
$SYNCFS_ROOT are overwritten by older ones which is definitely not
what you want. That's why an extra check is necessary.

So, just for the first time, when you just added a new directory to
VOYAGE_SYNC_DIR, you will have to manually copy it to  $SYNCFS_ROOT/ .

(Maybe an helper function could be added to
/usr/local/sbin/voyage-sync to do this syncing-without-checking
automatically, but definitely not in /etc/init.d )

-- 
G.