I'm guessing that you want to write close to two tapes every night in
order to maximize the frequency of full dumps. As others pointed out,
amanda is striving to balance the required level 0 dumps over the
configured dumpcycle. So, if you want more data as full dumps every
night, you'll need to change the dumpcycle parameters.
Run amadmin foo balance, and look at the TOTAL line. This gives the
total output KB for all level zeros, and then that value divided by
the number of runs per dumpcycle. If that value is, say, only 1.2
times the length of a tape (and therefore 60% of what you want to
use), you could decrease the dumpcycle. Remember to leave room for
incrementals and also room for late dumps so that amanda can catch up
when behind. Plus some to flush the previous nights incrementals if
you are using autoflush (I think; haven't tried this yet). I'd tend
to avoid the balanced fulls/run being more than about 1.3 times the
single tape, to leave a bit for incrementals and catchup.
My setup has a 3550 K tape (DDS2), with balanced size being 2665331.
This is 73% for fulls. This is just barely comfortable; if I am very
good about not missing tape changing it works ok. The distribution of
amount written is bimodal, with a peak around 2875K, and another
around 3540K. This suggests to me that when things go well, this fits
comfortably, but that amanda spends a lot of time maxing out the tape,
which to me indicates that dumps are getting deferred due to no space
on tape.
You'll either need xplot (in FreeBSD:/usr/ports/math/xplot,
NetBSD:/usr/pkgsrc/graphics/xplot) or munge the awk for gnuplot, but
this might be interesting:
(echo double double;cat log.* | egrep 'INFO tape.*OK' | \
awk '{val=val+1; print ". " val " " $6}' ) | xplot
Greg Troxel <[EMAIL PROTECTED]>
