Using zxfer to backup ZFS pools

I was recently looking for an easy way to backup some FreeBSD jails I have running various services. With the jails residing on top of ZFS (using iocage), a quick Google search turned up the usual zfs ‘send’ and ‘receive’ mixed with miscellaneous pipes and redirection. Having wrote several backup scripts in the past, they all felt sort of hack-ish and rushed (which they were). After thinking to myself “surely, someone has dealt with this problem before.” I finally came across zxfer.

I’m unsure of the original author and it was apparently abandoned several years ago around FreeBSD 8.2. Huge thanks to Allan Jude for maintaining the current port.

You can tell a lot of thought went into not just the program itself, but
the supporting documentation as well. I’m typically not one to judge a book by its cover, but with documentation like this, I feel it was a safe bet. It doesn’t just throw command line switches at you and set you on your way. Instead, nearly ever option explains why and when you might use it.

Goal:  Backup iocage jails to remote server (also running zfs).

Solution: Use iocage’s built-in snapshot management and zxfer to send those snapshots off-server and/or off-site.

Note, assume we’ve already got iocage setup and we’re running some jails. Also note, zxfer doesn’t perform any snap-shotting itself. Its up to you to setup a sensible snap-shotting regimen.

On the jail host, take a snapshot of all running jails

for j in $(iocage list | awk '/up/{print $4}'); do iocage snapshot ${j}; done 

Note, zxfer can be used in either a push or pull method, wherein the connection is initiated from the jail host or the backup server respectively. Here, I’ve decided to use the pull method.

On the backup server:

zxfer -dFkPv -g31 -O root@172.16.0.7 -R zroot/iocage/jailszroot/backups 

Assuming you’ve already setup SSH key authentication, from the backup server, we’re recursively sending all dataset snapshots under zroot/iocage/jails on the jail host (172.16.0.7) to our local zfs pool (zroot/backups), keeping the last 30 days of snapshots (on both servers).

After the initial sync, any further runs of the above command will send just the difference between the last two snapshots of the given datasets!