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Re: More than one tape per run
2003-10-27 03:53:34
Ah, I see. So it won't actually multiply tape size by runtapes when
trying to figure out how much it can write... I'm not sure the
functionaltiy is of much use to me then, but perhaps I could cheat and
pretend the tapes are "runtapes" times larger than they really are?
Won't buy you anything. Amanda will reach the actual end of the tape
and not be able to go on to a second tape because runtapes is 1.
What I meant was set, say, length (in tape config) = 2*<actual tape
size> *and* runtapes = 2.
Lying to amanda is not nice :)
No, it's probably a bad idea in most cases.
And again won't buy you anything.
I think it will buy me the ability to write, say, 4 tapes in 2 runs (2
in each run.) I can think of no other way to do that (given the
information that amanda will schedule only one tape's worth of data even
if I set runtapes to 2 or more.) I'm not saying that this is necessarily
something I want to do, though.
Hypothetical, 1 DLE, 1.5GB, a tape with an actual capacity of 1.0GB.
You set tape length to 1GB and runtapes to 1.
Amanda notes the impossibility of taping this and may refuse to do a level 0.
You leave tape length to 1GB and runtapes to 6.
Amanda continues to note the impossibility of taping that DLE.
You lie and set tape length to 2.0GB and runtapes to anything, but say 3.
Amanda does the dump of 1.5GB but hits end of tape (EOT) at 1.0GB.
It thinks there might have been a tape error because the admin said the
tape was 2.0GB so it tries the allowed tape 2 by starting to tape the dump
from the beginning. And hits EOT again. The same error is encountered
on every tape you allow amanda to use. You waste tons of taping time
doing an impossible task; fitting a 1.5GB dump into a 1.0GB box.
I don't think this is very relevant, though. I think I can safely assume
that any DLE will fit on a (real) tape; that's the way the disklist is
set up. If one doesn't at a given time, it will be fairly easy to tell
from the amdump output and make the appropriate adjustments to the
setup. And the fact that this one run will spend some extra time trying
(and failing) to write data isn't that much of an issue.
Another option I've been thinking about (again, if I decide I want to
write several tapes in one go) is simply to start another amdump once
the first is finished. I'm not sure if that's a idea either, though,
since amanda seems to be geared towards one run a day, and it will
probably increase overall backup time because dumps can't be
parallelised between the two runs.
- Toralf
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