Date: Fri, 27 Apr 2001 19:15:53 -0500 From: Mike Meyer <mwm@mired.org> To: "Nathan Vidican" <nathan@vidican.com> Cc: questions@freebsd.org Subject: Re: dump schedule Message-ID: <15082.3001.350719.230395@guru.mired.org> In-Reply-To: <69616681@toto.iv>
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Nathan Vidican <nathan@vidican.com> types: > How does one determine which dump levels to use for incremental backups? I > have been running a zero level dump nightly Monday through Friday on > different tapes. I would like to change the setup so that the backup only > backs up level zero every friday, and does incremental backups of only the > changed/altered files in the interim. What I'm having difficulty > understanding, is which level number I should be using. for example: 0 first > Friday, then 1 following Monday, then 1 every night until Thursday, and a > new zero level on Friday. Would this schedule be feasible? Will it function > properly as I am expecting? That would be a backup schedule, but there's room for improvement. You don't provide quite enough information to figure out exactly how to do what you want, but I'll cover some alternatives. The rule is: a level N dump backs up all changes since the last dump at a level lower than N. There are no dumps lower than level 0, so level 0s back up everything. With your proposed schedule, the level 1s that happen every night would include everything that has changed since the full dump done the last friday. I run things close to that, but you can make better use of levels. If that's what you want, I'd suggest making the daily backups near level 6. You'll back the same things up, but if the daily dumps get to big, you can do a special level 3 (or similar), and the dailys will then start backing up the changes since the level 3. If instead, you wanted the daily tapes to back up only that days changes, you'd do level 0 (Fri), then levels 1, 2, 3, and so on. The problems with increasing the level each day is that you then have to restore some unknown set of tapes - possibly five - and it's fragile. If some tape is dead, you lose that days changes, and restores of the remaining tapes won't be quite correct. Doing it the other way means you only have to restore two dumps - the level 0, and the daily tape. If the latest daily tape is fried, you still lose one days work - but can get a proper restore from the previous days tape. As a comment, I think weekly level 0s is overkill. I typically do level 0s at an interval dictated by the environment, then do level 4s weekly, and level 8s daily. That leaves level 9s for a quick dump before I do something that endangers the system, and three levels for interim dumps between the regular levels. For boxes tracking -release, I tend to level 0s after every release is installed. On my boxes, I do level 0s when the weeklies require changing media. I've had clients with 0s at intervals ranging from once a month to once a year (though the latter case did the first weekly of the month at a lower level than the other three). <mike -- Mike Meyer <mwm@mired.org> http://www.mired.org/home/mwm/ Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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