On May 25, 2011, at 3:52 PM, Rick O'Quinn wrote:

> I know there's not a "rule" but I was just wondering how long most people keep a backup? I have had a routine of archiving a weekly & monthly backup to an external disk, then cloning that disk. I was looking through my files today and realized I had a copy of the monthly archive going all the way back to 2000! Just started wondering, really, do I need to keep anything THAT old?

There is a difference between a "backup" and an "archive." A backup is a copy that is intended to contain a copy of the system that can be restored in the case of a data loss event. An archive is a snapshot of a system at a particular time, typically used for reference.

I keep backups around for a week, on a decreasing frequency schedule. For example:

Every hour for the last 8 hours (every hour, keep 8)
Every other hour for the last 24 hours (every 2 hours, keep 12)
Twice a day for the last 3 days (every 12 hours, keep 6)
Once a day for the last 7 days (once a day, keep 7)

This allows me to restore a previous version consistent with my memory of when a problem might have arisen.

As for archives, it's been a while since I've run production systems but the archives are typically defined by the data consumers. That is, if they need to be able to see what the system looked like at each month end, then you keep monthly archives.

For development purposes, I would look at archival more around development milestones rather than on any particular schedule. And for those you typically only need a clone of the files, not all of the data that goes with them.

Cheers,
-corn


Cornelius Walker
The Proof Group
http://proofgroup.com/