On Thu, 6 Dec 2001, Paul Bijnens wrote: >"Brandon D. Valentine" wrote: >> >> My quarrel seems to be with the fact that amanda is attempting to backup >> more data than will fit on a single tape. This might not be a tapetype >> problem, but it seems the logical place to start twiddling. It may be >> that planner is unable to get good estimates for some of this data so >> what it thought would compress to 35GB only became 46GB post dump. > > >That's probably the case. Planner gets an estimate of the uncompressed >sizes, and makes an educated guess to what ratio it will compress. >For it's education it uses the history of the last three dumps and computes >an average. If it has no history, it assumes by default 50% (but you can >change that in your dumptype with the comprate parameter).
This seems to be the case as last night's amdump run also ran over the tape length, but by a noticeably smaller amount. I went ahead and set comprate to 0.90 in my global dumptype so hopefully tonight's run will be a bit better. If it's still not getting good estimates I will just continue flushing the leftover dumps to tape until planner figures things out. >If for some reason, the data does not compress as well as it did in the >past (e.g. because someone replaced an almost empty database with the >same amount of mp3 files -- it happened to me) dumper has to consume a lot >more data than planner thought it would. It's more like I finally got all of the bugs worked out of my heterogenous amanda setup which means everything in the disklist is finally getting dumped, and most are starting at level 0. >> I've set length in tapetype to 33000mb, a good 2GB below what the tape >> will theoretically hold. Worst case scenario is that Amanda uses powers >> of 2 to define tape size and Sony uses powers of 10. If this is the >> case then 33000*1024*1024/1000/1000 = 34603 so I should still be safe. > >Actually, amanda informs you about the exact place where it bumped into EOT: > >> taper: tape Daily06 kb 34136032 fm 42 writing file: No space left on device > >That is 34136032 / 1024 = 33335 Mb >(Or should i count (34136032 + 42 * 500) / 1024 = 33356 Mb >So you're indeed on the safe side with 33000 mb capacity in your tapetype. That was my hunch. Thanks for checking my sanity. =) Brandon D. Valentine -- "Iam mens praetrepidans avet vagari." - G. Valerius Catullus, Carmina, XLVI
