Hi Winston, | For the longest time I did traditional backups (fulls and incrementals, via | tar). If that model still fits your needs, you can stay with that.
| Once I began backing up a small cluster of machines, Amanda's paradigm began to | show its value. However, it relies upon volume management, and it requires an | acceptance that "her" algorithms allow a more optimal distribution of backups | based on both availability of backup media (virtual or otherwise) and the | amount of individual and collective changes on the client machines - as well as | certain parameters I set such as the maximum interval I am willing to accept | between full backups. The benefit is that with the amount of space I've | allocated to vtapes, I get the maximum amount of change data on backup. It | isn't overprovisioning; it's about optimization. It's also proven itself in | restores, where instead of having to restore a full directory and then every L1 | and L2 delta, I can simply tell Amanda to restore | file-version-as-of-specific-date. | I highly suggest a read of this FAQ: [ | http://wiki.zmanda.com/index.php/FAQ:How_are_backup_levels_defined_and_how_does_Amanda_use_them%3F | | | http://wiki.zmanda.com/index.php/FAQ:How_are_backup_levels_defined_and_how_does_Amanda_use_them%3F | ] ; particularly the section about Amanda's planning strategy. If you "insist" | on constraining Amanda to one-volume-per-backup, you are basically going | against the strategy; without that capability, I don't think that Amanda's | overhead gives you anything you can't do with tar and a cron job. I understand how Amanda wants to try to "smooth" the mix of backup levels and filesystem sizes so that backup costs about the same amount of time and storage each cycle, and that is a very worthwhile goal, so I don't want to impede that. I also understand that tape discipline is already built-in to Amanda at a fundamental level, so I don't want to mess with that, either. So, I seek advice. Suppose "amanda.example.com" is backing-up "client.example.com" to "NAS0.example.com". My level 0 backups are typically 120GB and my level 1 backups are typically 5GB, and I have 2TB on NAS0. That's 120+6*5 = 150GB/week, meaning I have sufficient room for thirteen weeks of backup. This seems to me like it might be a pretty common scenario and that there might be example configs floating around that would size the vtapes for optimal use. Is there one? I have some questions: 1. Can I make my vtapes all 150GB, and then instruct Amanda to put one cycle (one level 0, and six level 1) on one vtape, meaning re-use a vtape multiple time in a backup cycle? I like this approach quite a bit, if it is possible. It "packages" one level 0 with all the attendant level 1 differentials and eliminates my strongest reservations about vtapes -- namely that I don't know where anything is. 2. Failing that, should I make my vtapes 120GB, so I can fit a level 0 backup on one vtape, but then will Amanda truncate level 1 backups, so that the vtapes storage requirement is NOT 120G, but more like 5GB? 3. Alternatively, I could make my vtapes all 5GB and then Amanda will have to span fourteen vtapes for the level 0? This might be optimal use of storage, but it scares me with added complexity. I won't know where anything is, meaning I will have to have Amanda tools to unpack a backup, and in the case of a disaster, that may be really inconvenient. I sure would like to have option 1, if I could... -- Chris. V:916.974.0424 F:916.974.0428
