Backing Up

[John M. Długosz]

So, how do you back up the huge NAS running ZFS?
Besides ad-hoc copying of the files to another place (or several places since they won't fit on a drive), is there some built-in feature for backing up the ZFS stuff complete with error checking codes?

 

[warri]

For backing up from ZFS to ZFS: http://doc.freenas.org/index.php/Replication_Tasks

 

[John M. Długosz]

For backing up from ZFS to ZFS: http://doc.freenas.org/index.php/Replication_Tasks

"a ZFS volume must exist on both PUSH and PULL."
Hmm, so that requires another NAS. I was thinking more along the lines of putting a HDD into a dock, and changing it for another one when prompted.

 

[fracai]

You could rig something up with zfs send outputting to a file. You might also be able to pipe that output through the split command. Verifying or restoring would require done tricky cat commands and disk swapping.

You could also only send a subset of datasets if you've split up your pool.

 

[titan_rw]

I would avoid sending zfs replication streams to any filesystem that's not zfs (with redundancy). They're not really guaranteed to be 'bit stable'. For example, if you saved a "zfs send tank@snap" onto an ntfs formatted drive, what happens if the disk experiences silent corruption? Zfs on the receiving end will detect the error, even though the ntfs system didn't. But zfs won't be able to fix the error, and as far as I know, it will simply error out and stop. Your entire zfs stream, which could be your entire pool, is now lost due to one bad bit from an ntfs drive.

Now you could make it bit stable on non zfs filesystems by using something like .par2 files, and generating a small amount of parity so that single bit errors can be corrected. But it's kind of a tedious manual process.

If you're going to backup to another non zfs capable system, I'd do a file level backup with rsync or something.