On 2006-10-10 16:36, Steven Settlemyre wrote:
> Dear List,
>
> I have recently stepped into an admin role where amanda is already set
> up. I have a lot of questions, but I'll try to limit myself. I'm running
> Amanda 2.5.0p2 on a Debian system. With an 8-tape changer.
>
> 1) How do I find out if hardware compression is turned on?
The easiest way is to insert a scratch tape (because it will be
overwritten with garbage), and type:
amtapetype -c /dev/nst0 (use the device file of your tape here)
It could be more complicated for certain Linux systems where the
compression status of the drive is automatically adapted to whatever
the tape inserted has, EVEN WHEN FOR SUBSEQUENT WRITING.
That means, there exist some environments where, when you read a
tape, the kernel sets the status of the inserted tape, and when you
write something afterwards, the setting is inherited from that read,
instead of the settings from command line. To get out this
situation you need to write something, without first reading from the
tape (amtapetype does a read to verify it is a new unwritten tape).
AFAIK recent kernels (I'm using CentOS 4.x, a RHEL 4 clone) do not
behave anymore like this, but older (e.g. Slackware 8, IIRC) do.
>
> 2) Why does the amreport show > 100% in the "Usage by Tape" section?
>
> USAGE BY TAPE:
> Label Time Size % Nb Nc
> Monthly47 4:44 43875264k 108.8 44 1088
100% is whatever you declared in the definition of the tapetype.
That number could have no resemblance to reality, and in fact, when
using hardware compression, should be some estimate depending on much
your data will compress, and hence will fit on the tape.
Amanda uses the value from the tapetype for planning and for the
tapefitting algorithms.
But while writing to the tape, Amanda does write until it hits
the physical end of tape (or a write error, many tapedevices do
not make a real distinction between EOT or a write error).
> 3) What do the levels mean? I think 0 means full backup, but what are
> the other numbers?
Level 0 = full backup, everything
Level N = all files changed since last level N-1
> That's a good start.
Let's go then. :-)
--
Paul Bijnens, xplanation Technology Services 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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