Mitch Collinsworth wrote:
The end result was that I had maybe 5-10% of the 1st tape taken up
with useful data, followed by a lengthy idle period while getting
this DLE's level 0 onto the holding disk (it was smbtar, so this
step took a long time), followed by something like 4 hours of
writing most but not all of this level 0 to tape 1, followed by 4+
more hours of writing this whole level 0 again on tape 2.
I also had such a situation, albeit not as bad (I used DDS2-tapes,
that's 4GByte, but the drives are slow). I ended up splitting the
large DLE's.
Especially since Amanda 2.4.3 and later, where you can specify
your disklist with excludes, it's became easier, like this:
some.host /disk1/oracle/product/9.0.1 comp-user-tar 2
some.host /disk1/oracle/product {
comp-user-tar
exclude "./9.0.1"
} 2
some.host /disk1/oracle {
comp-user-tar
exclude "./product"
} 2
some.host /disk1 {
comp-user-tar
exclude "./oracle"
} 2
It's a long time ago that the Oracle software would fit comfortably
on a 4 Gbyte tape; and if you ask people what's in that software, nobody
knows. :-)
If amanda had just skipped directly to tape 2 it would have finished
around lunch time and I could have said "I can do your restore this
afternoon."
Maybe a refinement to taperalgo (extra option?) .
What should taperalgo decide when e.g.the tape is 50% full, here are no
files ready on holdingdisk that fit on the current tape, but there are
still DLE's to be dumped some of which will fit.
Should it wait for those DLE's (wasting time), should it skip to the
next tape (wasting tape)? Or should it try the smallest one, and hope
it will fit (saving tape and time) or risk to run into end of tape
(wasting lots of time), or...
The situation would be much better if (maybe only some) DLE's would
be split across tapes, like suggested in a mail recently by Brian Cutler.
In this case you would only lose the last chunk that has to repeated
on the next tape. This lets you control your wasted tape and time,
by tuning your chunksize.
You could get even more complicated if you have two tape drives, and
let amanda fill the two drives at the same time, planning which DLE
goes on which tape to optimize the space and time. (I have no
changer but two drives, still less expensive than a changer, and you
have a spare drive when one goes bananas.)
--
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: Paul.Bijnens AT xplanation DOT com
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