On Mon, Jun 26, 2006 at 04:14:29AM -0700, Joe Donner (sent by Nabble.com) enlightened us: > Hi, > > can anyone please help me understand this: Apparently, you have to > calculate how many tapes you need for your backup schedule as the number of > tapes needed for every day the backup will run in your dumpcycle + one extra > tape to avoid the risk of overwriting a full backup performed at the > beginning of the previous cycle (quoted very loosely). >
The minimum amanda will run with is runspercycle * runtapes. I think most people recommend 2 * runspercycle * runtapes + 1, so that there are 2 complete sets of backups, plus a spare tape. > I want to: > > 1. Run a backup job once a day Monday to Friday (all my data will fit onto > one tape), All data Monday-Friday will fit on one tape, or each night all data will fit on one tape? > 2. Have four weeks' worth of "historical" backups, i.e. be able to restore > data to any given point within the last four weeks, and > 3. Permanently archive one monthly full backup. > > So how would I calculate the appropriate number of tapes needed? > > 5 days * 4 weeks + 1 = 21 tapes ?? > Assuming 1. above means you need just 1 tape per night, then for your 4 weeks of historical backup, 21 tapes would be sufficient. > If I don't force full backups, and therefore full backups are sort of > scattered between different tapes, then I'll have to take out multiple tapes > every month for archiving, right? How should that be managed? > You have 2 choices: Remove an entire "set" of tapes (1 complete dumpcycle, in your case 5 tapes), or run a second configuration with its own set of tapes that forces fulls. I do the latter. > What would appropriate values be for dumpcycle, runspercycle, and tapecycle? > I'm thinking: > > dumpcycle 7 days (to ensure a full backup at least once a week) > runspercycle 5 days (Monday to Friday every week) > tapecycle 21 (number of tapes in rotation assuming my calculation above is > correct) > That would work nicely. > I'd really appreciate your advice on this type of backup scheme, because I'm > struggling a bit to understand Amanda - they should have called her George > or something :) You're doing just fine :-) Matt -- Matt Hyclak Department of Mathematics Department of Social Work Ohio University (740) 593-1263
