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Re: dealing w/ huge data backups
2005-06-03 06:23:44
Cameron Matheson wrote:
many systems should be able to fit on one tape
(i'm using hw compression on tapes that hold a little
over 100GB w/ no compression). Anyway, the problem
now is that i need to back up a system that is
120GB.... i can split that up no problem (i'm just
using tar anyway), but the question is would it be
better to just bump up the 'runtapes' parameter to 2
or 3 tapes,
I'd like to give you a little stronger advice than the others: you
*definitely* need to split this one up. Really.
Just bumping runtapes will help you if you total backup size is larger
than one tape; but it won't help you at all if a single DLE is too large
to fit on one tape. amanda never splits a single DLE across tapes
(barring patches to the 2.5 series which I don't think you are using).
So essentially, whether or not you bump runtapes is a different
decision, but it won't help you for this huge DLE.
Now what happens is that amanda will most certainly finish dumping this
DLE rather late during her run, when the tape has already had a certain
number of dumps written to it. You could try to fiddle around with
dumporder and the number of dumpers, but I'm sure that's really not
worth it. Anyway, there's a fat chance that amanda would try to tape
the dump, hit EOF, and start over on the next tape. For a huge DLE,
that can mean tens of GB of wasted tape, along with the corresponding time.
Now just split up your DLE in lots of smaller units. By lots I mean
easily 10 or 20; I normally try to keep my individual DLEs below 10GB.
With this setup, when amanda hits EOF and retries on the next tape,
you'll never have more than 10GB of wasted space, and a lot less quite
often. And wait, there's a second advantage: amanda will schedule level
0's for different DLEs at different times. If you have a huge DLE, its
level 0 will take several hours to run, once every dumpcycle. If you
have lots of smaller DLEs, a few of them will get a level 0 every day,
others the next day, and so on.
Now for the actual splitting-up, if you need help or you want to run
your config by the list, feel free. I use a home-grown perl script
along with `du -xks *' output to split my DLEs, others do it by hand, it
all depends. Just for example, here's what a properly split huge disk
will look like:
# draco:/raid2
draco /raid2/PROJECT svcomp-work-tar 1
draco /raid2/DESC_SCANS svcomp-final-tar 1
draco /raid2/GENERIC svcomp-work-tar 1
draco /raid2/GAME svcomp-work-tar 1
draco /raid2/SPRITE svcomp-work-tar 1
draco /raid2/TMP svcomp-work-tar 1
draco /raid2 {
svcomp-work-tar
exclude append "./PROJECT"
exclude append "./DESC_SCANS"
exclude append "./GENERIC"
exclude append "./GAME"
exclude append "./SPRITE"
exclude append "./TMP"
} 1
# end draco:/raid2
Alex
--
Alexander Jolk / BUF Compagnie
tel +33-1 42 68 18 28 / fax +33-1 42 68 18 29
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