Synch Up With Rsynch for Quick-Restore Backup

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.
Posted November 5, 2008

Juliet Kemp

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 synchronise 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.

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Tags: PHP, data, server, IT, backup

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