Synch Up With Rsync for Quick-Restore Backup

by Juliet Kemp

Offsite backup and historical backup have their place, and their limitations. When it comes to rapid access to backed-up data in the event of a major disk crash, an instant slot-in replacement is needed, and rsync is well set for the task.

Juliet Kemp
As we are all (I hope ...) painfully aware, decent backups are absolutely vital. Last week I looked at a potential option for offsite backup, and solutions like Bacula are excellent for providing a stable, reliable onsite backup, with historical data available.

But these solutions don't provide rapid access to the backed-up data in the event of a major disk crash (e.g., if a centralized home disk bites the dust, leaving everyone on the system unable to work). What you want here is an instant slot-in replacement, and for this, rsync is an excellent option.

rsync doesn't keep historical data, but if all you want is a nightly current snapshot, it does that very well. You can use a "proper" backup solution for your historical data.

Either set rsync up onto a disk that you can physically slot in to your regular or another server; or use a spare machine that can be plugged in immediately instead (e.g., by changing your NFS mappings). Set up a cron job to synchronize nightly, and you're done. In the event of a serious main server crash, just slot in the new disk and get everyone up and running again with only 24 hours of data lost — which if your backup schedule permits, you can then recover at leisure.

Be aware that although this will work if the main disk crashes overnight — as rsync will not be able to access it so won't run — it will not work if something more subtle goes wrong. In this case, both disks will have corrupt data, and you're back to using your normal backups for a regular restore.

This article was originally published on Monday Nov 3rd 2008
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