On Mon, Feb 07, 2005 at 10:07:50AM +0200, Shai Ayal wrote:
> Hi all,
> 
> I understand that it is better to turn the tape drive's hardware 
> compression off and let Amanda know the real size of the tape and gzip do 
> the compression.

"better" is very subjective here.  There are valid reasons for choosing
hardware or software compression depending on your situation.  Many of
the regular responders on the list use SW compression (myself included)
and are vocal about their preference.  But their situation is not yours.

> So... How do I turn it off, or for that matter, how do I know if it's on or 
> off?

A question for which the response is hardware and OS dependent.  You may
be dealing with physical hardware option switches (in the case or outside),
front panel switches, software control such as with the mt command, OS
config files, or by selecting from several choices, a specific device name.

Check your mt command man page first.  Mine (Solaris) has no sub-commands
related to compression.  Others, notably linux, do.

> 
> My tape is a DLT 80/160 and I use the following for the tape size in 
> amanda.conf (from the amanda web site):
> 
> define tapetype DLTVS160 {
>    comment "DLT VS160 tape drive"
>    length 74529 mbytes         # 72.78 Gb
>    filemark 584 kbytes
>    speed 2203 kbytes           # 2.15 Mb/s
> }
> 
> So my tape is configures with it's uncompressed length. The backups seem to 
> be working as expected, but how to make sure there is no hardware 
> compression ?

I suspect that when you get things sorted out that the amtapetype command
suggested by Paul B in another response will report a higher capacity.
I'm guessing the above tapetype definition may have been made by a "tapetype"
command run with hardware compression turned on.

-- 
Jon H. LaBadie                  jon AT jgcomp DOT com
 JG Computing
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