Hi all! I'm stuck while reading my today Amanda report: 27 Gb backed up today that did not fit in 40 Gb (2 tapes of 20 Gb)! Well... It's normal, since: nearly all data were onto tape 1 (about 7 Gb). Another DLE tried to go on this tape, but too large (14 Gb). So it took the next tape and went on it. And the last DLE, that was around 7 Gb, did not fit onto this tape, and failed (I configured Amanda to use 2 tapes).
In recent (I believe 2.4.3 or later) version there is taperalgo and dumporder to tune this.
In my config I have set the options:
inparallel 10 # the number of dumpers taperalgo largestfit dumporder "TTTTTTTTTT" # as many T's as you have dumpers
And my the first 2 of my 3 tapes are filled near 100%!
I chose dumperorder T: longest first, because that way the slowest computer is finished faster. If you have another mix of slow/fast computers with small/large filesystems, then maybe "S" (largest first) could improve the tape usage in some boundary cases.
The taperalgo setting only works good enough if you have many images
to choose from. Taperalgo chooses only from those images that have finished dumping. For an easy explanation, lets asume you start 10
dumpers (inparallel 10) and choose to dump the largest first
(dumporder "SSSSSSSSSS") and all your filesystems on all your computers
have the same dumprate. The first one that will be finished is the
smallest of those 10. Taperalgo has only one image to choose from,
and starts taping this one. While it is taping this image the next
one to finish dumping is the next to smallest one, etc.
By the time taper finished its first image, it can choose between,
let's say 5 images. This is the time when you really see taperalgo
can optimize your tapeusage.
If you're in the case where all the smaller dumps finish too early, then you can even decrease the number of dumpers.
The default dumporder is (I believe) "sssSSSSS": if you have 5 large systems, and many smaller, it could happen that all the small dumps are finished before the first large one arrives. Then you have all your small dumps in the beginning of the tape, and the large dumps at the end. If a large dump hits EOT, it has to start all over again on the next tape; like you noticed, that could waste a lot of tape.
Because it's easier for amanda to fiddle with many smaller pieces than a few large ones, I break up my very large filesystems in a few smaller ones too.
-- Paul Bijnens, Xplanation Tel +32 16 397.511 Technologielaan 21 bus 2, B-3001 Leuven, BELGIUM Fax +32 16 397.512 http://www.xplanation.com/ email: [EMAIL PROTECTED] *********************************************************************** * I think I've got the hang of it now: exit, ^D, ^C, ^\, ^Z, ^Q, F6, * * quit, ZZ, :q, :q!, M-Z, ^X^C, logoff, logout, close, bye, /bye, * * stop, end, F3, ~., ^]c, +++ ATH, disconnect, halt, abort, hangup, * * PF4, F20, ^X^X, :D::D, KJOB, F14-f-e, F8-e, kill -1 $$, shutdown, * * kill -9 1, Alt-F4, Ctrl-Alt-Del, AltGr-NumLock, Stop-A, ... * * ... "Are you sure?" ... YES ... Phew ... I'm out * ***********************************************************************
