On Wed, 5 Dec 2001, Anthony Valentine wrote: >Your tapes hold 35GB native.
Correct. >You are backing up: 76399.8 MB (76GB) > >Compressed, that is: 46003.2 MB (46GB) > >Because you use software compression, you have to go by the native capacity >of your tapes. So even compressed, you data won't fit on one tape. 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. >The only options that I can see are to try to get better compression by >using 'gzip --best' (if Amanda can support adding switches to gzip) or >getting larger tapes. This is unacceptable as I have found that "gzip --best", which amanda does support, causes a nearly exponential increase in the time it takes amdump to run. A considerable fraction of my clients are r5k/r10k/r12k MIPS machines and none of them are terribly fast at gzip as it is. Few of the GNU tools are particularly well optimized for the SGI MIPS platform. Larger tapes are also not available for AIT-1. >Setting the length option in the tapetype clause to more than your tape can >hold probably won't help you any. Correct me if I'm wrong but what I have set the length option to is well _below_ what the tape will hold. With 35GB capacity tapes I have 35000mb or 35840mb depending upon whether Sony uses powers of 2 (the computer science definition) or powers of 10 (the marketing definition) when defining their tape size. I'll go with the former to be safe. 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. Brandon D. Valentine -- "Iam mens praetrepidans avet vagari." - G. Valerius Catullus, Carmina, XLVI
