Thread: ZFS
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Old 30th December 2008
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phoenix phoenix is offline
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We use rsync to backup out remote servers (82 so far) to the backup box running FreeBSD+ZFS, taking a snapshot of the backup directory each night. We do full rsyncs of the entire remote system (everything except /proc, /sys, /tmp, and /dev), into separate directories for each server. That way, we can do full system restores as well as single-file recoveries.

After the initial sync, which can take a few days across an ADSL link, the follow-up syncs take between 30 seconds and 2 hours, depending on the amount of data that has changed and the speed of the link.

Our backup script is configured such that it starts 1 backup process per remote site, waiting 7 minutes before starting the next process. That process then runs rsync for each server at the site in sequence. So we can have up to 15-ish rsync processes running at a time. (In theory, we could have 55 running at once, as that's the number of remote sites we have, but they tend to finish fast enough that we never have more than around 15 running.)

As for the off-site replica of our backup box, I'm still running tests with the ZFS send/recv stuff. The atomic nature of the snapshot feature can be a bit touchy. For example, trying to do a # zfs send storage/backup@20080805 | ssh remoteserver "zfs recv storage/backup@20080805 would fail on me. Turns out, that was combining 4 snapshots, and trying to send 1.2 TB of data across the network. The SSH connection would fail after 36-ish hours, then the box would spend about 12 hours deleting all the data transferred so far. Breaking the process up into "zfs send pool/snapshot > file", "scp file remoteserver:", and "zfs recv pool/snapshot < file" steps makes it a lot smoother. Less automated, but more reliable.

Now I'm in the process of brining the replica box up-to-date with the 100+ snapshots we've taken so far.
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