I can check it with mt -f /dev/st0 status, but there I can not see anything
about the compression. However, there is a density code 0x1a (unknown)
parameter. Might that be the problem?
Paul Bijnens To: Arne.Briesenick.ext AT
deutsche-boerse DOT com .
<paul.bijnens AT xplanation DOT co cc: amanda-users AT
amanda DOT org
m> Subject: Re: strangeTape size
problem [Deutsche Boerse Systems:Virus
checked]
28.04.2004 13:31
Arne.Briesenick.ext AT deutsche-boerse DOT com wrote:
> you are right in terms of operating system. Its Linux.
> It seems to be a problem with the amanda configuration. And it might be
the
Amanda itself has no parameter for hardware compression ON or OFF.
It just uses the device as given.
Also the numbers in amtapetype are just used for planning; the tapesize
in amtapetype is not used as an upperbound when writing to tape.
> HW-compression of the drive. But I've deactivated the HW-compression at
the
> drive itself and the checks with mt -f /dev/st0 datcompression says that
> the compression is off...
I don't have a DLT-drive here, I can't verify.
Some drives (my AIT-drive does) have 2 dipswitches: one to set hardware
compression ON or OFF as default setting, and another one to let it
be controlled by software.
And there are different ways to indicate compression. Some drives use
"density codes".
That's why you better check with "mt -f /dev/st0 status".
The "mt" command on my Linux doesn't even recognize the "datcompression"
option. But it sounds peculiar to DAT aka DDS tapes to me.
The "amtapetype" command will detect if you have hardware compression
on of off. And it does write without reading. Run as "amtapetype -c"
it takes only a few minutes.
After amtapetype does not indicate you have hardware compression on,
then use that tape and "amlabel" it. I'm quite certain that in that
the combination tape-drive-amandasoftware has hardware compression
disabled.
> SW-compression I don't use actually to ensure that I don't run into
trouble
> with this feature interfeing other problems ...
But it could be that the contents itself were almost non-compressable
(e.g. mp3 files, jpegs,...) and doing hardware compression (by accident)
on those files still expands the data, resulting in tape overflow.
--
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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