Re: Ramifications of dump cycle and number of tapes choices
Hi, though the question is fairly old I found the answer just now: Gene Heskett wrote: I've got a silly Q myself over this one, and the man page is no help for this. But what does it mean when out in the future tense columns, one gets an 01 or a 10 or a 1E. Samples from the rather lengthy report on my system with 58 LDE's: --- date 12 12 12 12 12 12 12 12 12 12 12 01 01 01 01 01 01 01 01 01 01 01 01 01 host disk 21 22 23 24 25 26 27 28 29 30 31 01 02 03 04 05 06 07 08 09 10 11 12 13 coyote /dos 1 1 1 1 1 1 1 0 1 1 1 0 0 1 1 1 1 1 1 1 0 01 1 0 coyote /etc 1 1 1 1 1 1 1 0 1 1 1 0 1 1 0 1 1 1 1 1 1 01 1 1 coyote /lib 1 1 1 1 1 0 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 10 1 1 coyote /misc/deb11 1 1 1 0 1 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 1E 1 1 coyote /misc/deb81 1 1 1 1 0 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 10 1 1 coyote /misc/fedora/disk31 1 1 1 1 0 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 10 1 1 coyote /rh8.0disks/disk3 1 1 1 1 1 1 0 1 1 1 1 1 1 1 0 1 1 1 1 1 1 01 1 1 coyote /root 1 1 1 2 2 0 1 1 1 1 2 2 2 0 1 1 1 1 2 2 2 10 0 1 coyote /sbin 0 1 1 1 1 1 1 1 0 1 1 0 1 1 0 1 1 1 1 1 1 01 1 1 --- The odd numbers are all in that same column, these culled from the report I get here. Also, dumpcycle=8, runspercycle=8, tapecycle=28, runtapes=1 ATM. tense columns mean: amdump ran more than once that day. And 'E' stands for an error. Thus on the 11th Jan amdump ran twice (maybe one started at 00:01 and the other at 23:59), DLE coyote:/misc/deb1 was dumped at level 1 and then had an error on the 2nd dump. regards Georg -- ___ ___ | + | |__Georg Rehfeld Woltmanstr. 12 20097 Hamburg |_|_\ |___ [EMAIL PROTECTED]+49 (40) 23 53 27 10
Re: Ramifications of dump cycle and number of tapes choices
On Wednesday 28 January 2004 16:22, Georg Rehfeld wrote: Hi, Thanks Georg. Someone else had explained it to me also, but this a actually a bit clearer an explanation, thanks. though the question is fairly old I found the answer just now: Gene Heskett wrote: I've got a silly Q myself over this one, and the man page is no help for this. But what does it mean when out in the future tense columns, one gets an 01 or a 10 or a 1E. Samples from the rather lengthy report on my system with 58 LDE's: --- date 12 12 12 12 12 12 12 12 12 12 12 01 01 01 01 01 01 01 01 01 01 01 01 01 host disk 21 22 23 24 25 26 27 28 29 30 31 01 02 03 04 05 06 07 08 09 10 11 12 13 coyote /dos 1 1 1 1 1 1 1 0 1 1 1 0 0 1 1 1 1 1 1 1 0 01 1 0 coyote /etc 1 1 1 1 1 1 1 0 1 1 1 0 1 1 0 1 1 1 1 1 1 01 1 1 coyote /lib 1 1 1 1 1 0 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 10 1 1 coyote /misc/deb1 1 1 1 1 0 1 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 1E 1 1 coyote /misc/deb81 1 1 1 1 0 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 10 1 1 coyote /misc/fedora/disk31 1 1 1 1 0 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 10 1 1 coyote /rh8.0disks/disk3 1 1 1 1 1 1 0 1 1 1 1 1 1 1 0 1 1 1 1 1 1 01 1 1 coyote /root 1 1 1 2 2 0 1 1 1 1 2 2 2 0 1 1 1 1 2 2 2 10 0 1 coyote /sbin 0 1 1 1 1 1 1 1 0 1 1 0 1 1 0 1 1 1 1 1 1 01 1 1 --- The odd numbers are all in that same column, these culled from the report I get here. Also, dumpcycle=8, runspercycle=8, tapecycle=28, runtapes=1 ATM. tense columns mean: amdump ran more than once that day. And 'E' stands for an error. Thus on the 11th Jan amdump ran twice (maybe one started at 00:01 and the other at 23:59), DLE coyote:/misc/deb1 was dumped at level 1 and then had an error on the 2nd dump. regards Georg -- Cheers, Gene There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order. -Ed Howdershelt (Author) 99.22% setiathome rank, not too shabby for a WV hillbilly Yahoo.com attornies please note, additions to this message by Gene Heskett are: Copyright 2004 by Maurice Eugene Heskett, all rights reserved.
Re: Ramifications of dump cycle and number of tapes choices
On Tuesday 13 January 2004 01:24, Jon LaBadie wrote: [...] In ANY seven consecutive tapes there should be AT LEAST one full dump of each disk list entry. The reason for the at least is that amanda tries to balance the amount of tape used daily. To do so it may promote a full dump before it is needed according to the dumpcycle. I've got a silly Q myself over this one, and the man page is no help for this. But what does it mean when out in the future tense columns, one gets an 01 or a 10 or a 1E. Samples from the rather lengthy report on my system with 58 LDE's: --- date 12 12 12 12 12 12 12 12 12 12 12 01 01 01 01 01 01 01 01 01 01 01 01 01 host disk 21 22 23 24 25 26 27 28 29 30 31 01 02 03 04 05 06 07 08 09 10 11 12 13 coyote /dos 1 1 1 1 1 1 1 0 1 1 1 0 0 1 1 1 1 1 1 1 0 01 1 0 coyote /etc 1 1 1 1 1 1 1 0 1 1 1 0 1 1 0 1 1 1 1 1 1 01 1 1 coyote /lib 1 1 1 1 1 0 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 10 1 1 coyote /misc/deb11 1 1 1 0 1 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 1E 1 1 coyote /misc/deb81 1 1 1 1 0 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 10 1 1 coyote /misc/fedora/disk31 1 1 1 1 0 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 10 1 1 coyote /rh8.0disks/disk3 1 1 1 1 1 1 0 1 1 1 1 1 1 1 0 1 1 1 1 1 1 01 1 1 coyote /root 1 1 1 2 2 0 1 1 1 1 2 2 2 0 1 1 1 1 2 2 2 10 0 1 coyote /sbin 0 1 1 1 1 1 1 1 0 1 1 0 1 1 0 1 1 1 1 1 1 01 1 1 --- The odd numbers are all in that same column, these culled from the report I get here. Also, dumpcycle=8, runspercycle=8, tapecycle=28, runtapes=1 ATM. -- Cheers, Gene There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order. -Ed Howdershelt (Author) 99.22% setiathome rank, not too shabby for a WV hillbilly Yahoo.com attornies please note, additions to this message by Gene Heskett are: Copyright 2003 by Maurice Eugene Heskett, all rights reserved.
Ramifications of dump cycle and number of tapes choices
Hello, I was trying to think through what we want our dump cycle and total number of tapes to be, and I realized that I wasn't quite clear on some things. We have a changer with a capacity of 33 tapes. We have Amanda configured for a 7 day dump cycle, backups every night. Our backups currently use only 1 tape per run. I'm trying to figure out what our minimum service level guarantee would be if we used 33 tapes in our changer and we assume that it's 1 tape per run. Are the following statements correct? 1. We will have a full dump of any given partition somewhere on the most recent 7 tapes and that to restore a file to any given date in the past 7 days would take at most 7 tapes/steps but on average 3.5 tapes/steps. 2. We can retrieve a file as it existed on any date in the past 27 days, and possibly as it existed on days 28-33 (with Amanda shifting around full dumps, you never know how old the oldest full dump available will be, but you will know that it will be at least 27 days old, right? My thinking is that to retore any file you need to start with a full dump, and with 33 tapes and a 7 day cycle, if day 34 was a full dump, days 33, 32, 31, 30, 29, and 28 could have been incrementals before a forced full on 27. Hence, it seems you are guaranteed to be able to retrieve any file as it existed 27 or less days ago. I don't really want to start using Amanda in the manner of CVS where I start retrieving older versions of files where newer ones exist on a regular basis, but I would like to know the boundaries for when we do need to do this. Thanks, Fran -- Fran Fabrizio Senior Systems Analyst Department of Computer and Information Sciences University of Alabama - Birmingham [EMAIL PROTECTED] (205) 934-0653
Re: Ramifications of dump cycle and number of tapes choices
On Mon, Jan 12, 2004 at 06:56:25PM -0600, Fran Fabrizio wrote: [Assuming dumpcycle=7, runspercycle=7, runtapes=1, tapecycle=33:] Are the following statements correct? 1. We will have a full dump of any given partition somewhere on the most recent 7 tapes Yes. As you've figured out, precisely where is up to Amanda. and that to restore a file to any given date in the past 7 days 27 days, actually (looking ahead to question #2). The file might not be in the most recent dump cycle, but whichever cycle it's in is still only 7 tapes long... would take at most 7 tapes/steps but on average 3.5 tapes/steps. In your case, I think the numbers are 4 and very roughly 2, resp. Amanda doesn't always bump a given DLE to the next dump level; whether it does is determined by how much tape it would save by doing so (see amanda.conf parameters bumpsize, bumpmult, and bumpdays). With your parameters, and with the default bumpdays value of 2, the maximum number of tapes for a restore is 4: Day: 1 2 3 4 5 6 7 8 Level: 0 1 1 2 2 3 3 0 (With bumpdays=1, you'd be right; the maximum would be 7.) As for the average number of tapes... The vast majority of DLEs never get above level 1 or 2 in my experience; their dump histories look more like 011011... or 01101112 Thus, as an estimate of the average number of tapes to be read for a restore, (maximum_possible_dumplevel/2) is on the high side (in your case, max/2 = 2 is pretty close, but that's purely by accident). (maximum_actual_dumplevel/2) is probably low; the DLE spends a lot more days at the maximum dump level than it does climbing up to it. There are too many variables, I think, to estimate the average number of tapes without looking at your actual dump history, though the two formulas above might serve as *very* rough bounds. My estimate of 2 for your average is very much back-of-the-envelope guesswork: - for all those DLEs that never get above dump level 1, the average is 1.9 ((1 + 2 + 2 + 2 + 2 + 2 + 2) / 7). - for the few DLEs that stop at dump level 2, the average is 2.4 ((1 + 2 + 2 + 3 + 3 + 3 + 3) / 7), but only approximately; the DLE might bump to level 2 later, making the average a bit lower - for the *very* few DLEs that go to level 3 or above, the average will be higher still - but the level-1 DLEs outnumber all the rest combined, so 2 seems as good a guess as any But then, all of this pseudomathematical blather only applies to restores of many files (full-DLE disaster recovery, or a user-requested restore of an entire directory). For a single-file restore, you should only to need to read *one* tape. Amrecover will figure out in advance which tape the desired file lives on, so it won't need to search the rest. 2. We can retrieve a file as it existed on any date in the past 27 days, and possibly as it existed on days 28-33 This looks right to me. Hence, it seems you are guaranteed to be able to retrieve any file as it existed 27 or less days ago. Almost guaranteed :-( Be aware that in a panic situation, a full backup can be postponed to a run after the one where it should have been done (delayed is the word Amanda actually uses). If that happens, there will come a day or two, a month or so hence, when you can't quite meet your 27-day guarantee. Amanda tries hard to avoid delaying full backups, but it can happen, due to things like tape errors, operator failing to mount the right tape (shouldn't be an issue for you), tape filling up before it was expected to, and possibly other circumstances that aren't coming to mind right now. -- | | /\ |-_|/ Eric Siegerman, Toronto, Ont.[EMAIL PROTECTED] | | / It must be said that they would have sounded better if the singer wouldn't throw his fellow band members to the ground and toss the drum kit around during songs. - Patrick Lenneau
Re: Ramifications of dump cycle and number of tapes choices
On Mon, Jan 12, 2004 at 10:31:48PM -0500, Eric Siegerman wrote: On Mon, Jan 12, 2004 at 06:56:25PM -0600, Fran Fabrizio wrote: [Assuming dumpcycle=7, runspercycle=7, runtapes=1, tapecycle=33:] Are the following statements correct? 1. We will have a full dump of any given partition somewhere on the most recent 7 tapes Yes. As you've figured out, precisely where is up to Amanda. Just a slight revision. In ANY seven consecutive tapes there should be AT LEAST one full dump of each disk list entry. The reason for the at least is that amanda tries to balance the amount of tape used daily. To do so it may promote a full dump before it is needed according to the dumpcycle. For example, here is a part of the output of amoverview for a config with a dumpcycle of 7 and a runspercycle of 6. Note /var sometimes gets two full dumps in a row, others more frequently than every seventh day. date 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 01 01 01 host disk 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 01 02 03 butch / 1 1 1 0 1 1 1 1 1 0 1 1 1 0 1 1 1 butch /opt1 1 1 0 1 1 1 1 1 0 1 1 1 1 1 0 1 butch /var1 1 1 0 1 2 0 0 1 2 2 2 0 1 1 2 2 butch /img 000 butch /u 1 1 1 1 1 0 1 1 1 0 1 1 1 1 0 1 1 butch /u2 1 0 1 1 1 1 1 0 1 1 1 1 1 0 1 1 1 butch /w 1 1 1 1 1 0 1 1 1 0 1 1 1 1 1 0 1 butch /w2 1 1 1 1 1 0 1 1 1 0 1 1 1 1 1 0 1 butch /w3 000 The ones without incrementals are specified that way in the disklist. Also, other sites, with different data usage patterns, will have other experiences, but I seldom see any dump levels 2. Thus, for a small set of files, generally a restore only takes a single, maybe two tapes. A major restore might take three tapes. -- Jon H. LaBadie [EMAIL PROTECTED] JG Computing 4455 Province Line Road(609) 252-0159 Princeton, NJ 08540-4322 (609) 683-7220 (fax)
