On Wed, Mar 06, 2002 at 04:59:07PM -0500, Eric Trager wrote:
> I found out that I generally could get ~70 GB on a DLT-IV tape if I used
> hardware compression, so I set amanda's tape length to 60 GB and started
> backing up big partitions.
>
> I was able to backup 55 and 52 GB partitions, but there's one 50 GB
> partition is particular that won't fit on a tape, apparently. I've
> attempted it several nights in a row, but with no success, even when
> amanda starts the tape with it.
>
> Is what hardware compression can do with files variable? In this case,
> with the failure, it's a lot of oracle data, some of it is gzipped.
Sounds like you've answered your own question. :-)
Your tape drive is either a DLT-7000 and has 35GB native capacity (or a
DLT-8000 with 40GB native).
If you use the HW compression device, and your data is compressible,
great, you get >35GB. I've got my DLT-7000 set in my amanda.conf for
60GB. Works great for me.
If your data is uncompressible, you're screwed. Your capacity is
-guess what- 35GB (actually a little less).
You can try SW compression, in the hope that your data is somewhat
compressible and gzip can do sufficiently better (compared to the
tape drive HW) to squeeze it into 35GB. You can dump/tar into
a gzip/wc pipe to check that out, something like:
% tar cf - /something | gzip -c --fast | dd of=/dev/null bs=1k
% tar cf - /something | gzip -c --best | dd of=/dev/null bs=1k
If you can't get <35GB out of this, you'll have to break the the
file system up into multiple disklist entries, or buy a bigger
tape drive.
--
Jay Lessert [EMAIL PROTECTED]
Accelerant Networks Inc. (voice)1.503.439.3461
Beaverton OR, USA (fax)1.503.466-9472
