Re: Appropriate number of tapes in a set
Hi, thanks for your explanation. But I think maybe I'll just crawl around for a bit before trying to walk! It does sound interesting though - I'll keep it in mind for when I'm more comfortable with Amanda. Best regards, Joe -- View this message in context: http://www.nabble.com/Appropriate-number-of-tapes-in-a-set-tf1848286.html#a5062163 Sent from the Amanda - Users forum at Nabble.com.
Re: Appropriate number of tapes in a set
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
Re: Appropriate number of tapes in a set
Thanks very much for clarifying that to me. Yes, I meant that (at least at present) all data will fit onto one tape for every day of the week, i.e. if a full backup is done every day Monday to Friday, then Monday's full backup will fit onto one tape, Tuesday's will fit onto one tape, and so on. About the second configuration for doing monthly archival backups: 1. I assume then that you'd have to do something once a month to prevent the normal Amanda backup job from running while the monthly full one is active? I seem to remember I read somewhere about placing a file called hold inside an Amanda directory to cause the normal daily run to pause so it doesn't interfere with your monthly job - and so that you don't have to modify your cron job each time? 2. In other words, if you have a second configuration for monthly archives, then you really just happily rotate your 21 tapes for the normal daily backups, and then replace them one at a time either when they die naturally or when they've reached their expiry date? Thanks again - I think this has made things click somewhere in my head. -- View this message in context: http://www.nabble.com/Appropriate-number-of-tapes-in-a-set-t1848286.html#a5045679 Sent from the Amanda - Users forum at Nabble.com.
Re: Appropriate number of tapes in a set
On Mon, Jun 26, 2006 at 05:01:44AM -0700, Joe Donner (sent by Nabble.com) enlightened us: Thanks very much for clarifying that to me. Yes, I meant that (at least at present) all data will fit onto one tape for every day of the week, i.e. if a full backup is done every day Monday to Friday, then Monday's full backup will fit onto one tape, Tuesday's will fit onto one tape, and so on. About the second configuration for doing monthly archival backups: 1. I assume then that you'd have to do something once a month to prevent the normal Amanda backup job from running while the monthly full one is active? I seem to remember I read somewhere about placing a file called hold inside an Amanda directory to cause the normal daily run to pause so it doesn't interfere with your monthly job - and so that you don't have to modify your cron job each time? Yes, I usually put the Monthly tape in the drive, then schedule an at job for later in the evening that basically does touch /etc/amanda/Dailies/hold amdump Monthly rm /etc/amanda/Dailies/hold 2. In other words, if you have a second configuration for monthly archives, then you really just happily rotate your 21 tapes for the normal daily backups, and then replace them one at a time either when they die naturally or when they've reached their expiry date? Thanks again - I think this has made things click somewhere in my head. Yep, that's it. With the Monthly archive configuration, you'll probably want to set record to no in your amanda.conf so that your system doesn't count those as being full dumps and messing up your schedule every month. Other than that, it's pretty straightforward. Matt -- Matt Hyclak Department of Mathematics Department of Social Work Ohio University (740) 593-1263
Re: Appropriate number of tapes in a set
Matt, thank you very much for your advice - it has helped me out a great deal to understand what to do. Much appreciated!! Regards, Joe -- View this message in context: http://www.nabble.com/Appropriate-number-of-tapes-in-a-set-t1848286.html#a5046521 Sent from the Amanda - Users forum at Nabble.com.
Re: Appropriate number of tapes in a set
On Mon, Jun 26, 2006 at 05:01:44AM -0700, Joe Donner (sent by Nabble.com) wrote: Thanks very much for clarifying that to me. Yes, I meant that (at least at present) all data will fit onto one tape for every day of the week, i.e. if a full backup is done every day Monday to Friday, then Monday's full backup will fit onto one tape, Tuesday's will fit onto one tape, and so on. About the second configuration for doing monthly archival backups: Now that you are considering a second configuration, consider using hard disks for your daily backups. It appears you want a regular archive for disaster or required retention of data. But the daily requirement will be more for opps I didn't mean to type rm xxx type of needs. Virtual tapes, using disk space as tapes, is ideal for this latter type of need. Fast, no physical changer, simple to setup once you've experienced setting up any amanda config, and really convenient to retreive individual files as you need not go and get the specific tapes, they are always in the changer. Plus, disk space, even external usb or nas drives are pretty inexpensive these days. -- Jon H. LaBadie [EMAIL PROTECTED] JG Computing 4455 Province Line Road(609) 252-0159 Princeton, NJ 08540-4322 (609) 683-7220 (fax)
Re: Appropriate number of tapes in a set
That's an interesting suggestion, but I don't really follow on how to do this in practice. Are you saying that you do daily backups just to disk, and only rely on monthly backups on tape which are then kept off-site? Or do you mean do backups to both disk and tape - to disk for fast recovery and to tape for safekeeping? I'd be very interested to understand this concept :) Thanks for the suggestion. Regards, Joe -- View this message in context: http://www.nabble.com/Appropriate-number-of-tapes-in-a-set-t1848286.html#a5050318 Sent from the Amanda - Users forum at Nabble.com.
