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Re: Multiple tape servers
2009-09-12 16:41:53
Dominic Lepiane wrote:
Dear list
With our Amanda setup, we've got two tape autoloaders attached to two
separate servers. I had initially tried to run both autoloaders on 1
server, but they were giving me a lot of trouble so we went with two
separate servers. They're both Ultrium 2 tapes and the one autoloader
has 8 tapes and the other has 16 tapes (and happens to have a barcode
scanner). We've been running both basically independently, one
backing up some hosts the other backing up the rest. But our backups
have grown such that the 8 tape system is keeping data from a much
shorter period of time. As it stands now, I'm just going to rebalance
which hosts are backed up to which server and will probably have to do
so again in 3-6 months...
So I was wondering if it's possible to have roughly 1 amanda server
feeding backups to two tape hosts giving us logically a 24 tape pool
to work with rather than managing the two pools separately.
The other question I had was whether it is possible to split up the L0
backups from the incremental backups. We are taking weekly L0 backups
and we would like to keep the L0s around longer rather than having the
tapes reused by incremental backups. Could we for example, do the L0
backups with our 16 tape server and the L1+ backups with the 8 tape
server? Or, could we send the L0 backups to tape and L1+ to disk?
One obvious question would be, why restrict yourself to 8 or 16 tapes? I
have a 16 tape library, and I run more than a 30 tape cycle. I just swap
out about 5 tapes every week, so part of the cycle lives in a box, and
part lives in the tape library. I typically have the most recent two
weeks and the next week to be run in the library.
If you are running two different Amanda servers, you can't separate out
level 0 backups to one and level 1 backups to the other. By definition,
the level 1 has to refer back to a level 0, and the second server won't
know anything about the level 0 run by the other server. The best bet is
usually to let Amanda juggle the backup levels and smooth the demand
over the dump cycle.
Some people use a strategy of having Amanda do incrementals only to a
holding disk and then flush those out to tape with the full backups on
another day. So, maybe running incrementals through the week and then
letting Amanda put it all on one tape at the end of the week. However,
the point of that is to make fuller use of their tapes and make the
tapes stretch out longer. It sounds like you are filling your tapes,
although you haven't said what your strategy is.
It would be very interesting to have Amanda use a centralized planner
and send assignments to one or another backup server that has a tape
library. That would allow Amanda to do the balancing, and it would keep
the information accessible centrally. It could be imagined as master and
slave servers, or cooperative servers, or . . . . But, I've never heard
anyone talk about anything like that.
--
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Chris Hoogendyk
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O__ ---- Systems Administrator
c/ /'_ --- Biology & Geology Departments
(*) \(*) -- 140 Morrill Science Center
~~~~~~~~~~ - University of Massachusetts, Amherst
<hoogendyk AT bio.umass DOT edu>
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Erdös 4
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