http://www.mail-archive.com/zfs-discuss@opensolaris.org/msg19239.html

It’s funny, I’m looking to do something similar to this, but on FreeBSD. However, since I don’t trust zfs send/receive, I’ll be doing it with rsync as I want verification that the bits that end up on the target are the same as those that were read from the source. I’m pretty sure that rsync does that. I think this means that in order to get the snapshot goodness on the backup (assuming a different pool), you have to clone the snapshot, rsync it across, and take a snapshot on the target.

I suppose you could do it with zfs send provided that you do some sort of MD5 check yourself afterwards.

On http://opensolaris.org/os/community/on/flag-days/pages/2008042301/
Sun’s Matthew Ahrens says:
‘We have always disclaimed backwards compatibility of the “zfs send” stream format in the zfs(1m) manpage:

The format of the stream is evolving. No backwards com-
patibility is guaranteed. You may not be able to receive
your streams on future versions of ZFS.

However up until now we have maintained compatibility regardless.

All Solaris 10 releases use the new, post-build-35 stream format, so no incompatibility will be introduced to Solaris 10.

We plan to maintain backwards compatibility of the “zfs send” stream format throughout all releases of Solaris, and intend to commit to this backwards compatibility at some point in the future.’

On http://opensolaris.org/jive/thread.jspa?messageID=389857&tstart=0
or http://www.mail-archive.com/zfs-discuss@opensolaris.org/msg26438.html
Daniel Carosone says:
“The zfs send/recv format is not warranted to be compatible between revisions.

I’m concerned that, despite clear recommendations and advice against it, there seem to be a number of solutions appearing (like automated backup to cloud, via the auto-snapshot hooks) that use the stream format for long term storage, even from those within Sun. I think the message needs to be clear, either way – either endorse stream-format compatibility, or discourage such usage.”

Also, it looks like the next versions of the ‘Time Slider’ software in OpenSolaris 2008.11 will soon come with the ability to send incremental backups between two snapshots across the network to a second box, like a backup server. See:

http://blogs.sun.com/erwann/entry/zfs_on_the_desktop_zfs : look under the ‘What’s next?’ heading where it says ‘- network based backups’

I already have this functionality working on an adhoc basis, but it will be nice to have this setup once and then automated when this new functionality becomes available.

# zfs set atime=off tank/testback