Frederic,

This is _generic_ information that may or may not apply to your
particular tape drive.

- Turning on/off hardware compression is specific to your tape drive,
  not the changer.
- Look in the manual for a dip switch that may turn on/off the
  compression.
- There's another dip switch that allows for software control of
  hardware compression regardless of the position of the dip switch
  described above.
- If the second dip switch is set to enable software control, you'll
  be able to control the compression using the 'mt' command.
- Find the device file name of the tape drive (not the changer),
  e.g. /dev/nst0
- To turn on hardware compression:
   mt -f /dev/nst0 compress 1
- To turn off hardware compression:
   mt -f /dev/nst0 compress 0
- The effect of your command lasts until the tape is ejected.
- If you plan on using compressionr a lot, you should set the default
  behavior using the first dip switch described above.
- This is not Amanda-specific information, but might be appropriate
  for inclusion in the amanda document. (Hint, hint.) :)

Hope that answers the question.

Ivan


Frederic Medery a e'crit:

> Hello, I'm using amanda with IBM 3581 tapechanger,
> my tapetypes.conf is :
> 
> # IBM LTO Ultrium 3581 tape Charger
> define tapetype IBM-LTO3581 {
>         comment "IBM LTO Ultrium 3581 (Hardware Compression off)"
>         length 100608 mbytes
>         filemark 0 kbytes
>         speed 13120 kps
> }
> 
> 
> I'm gonna use dump instead of tar so I want to enable hardware 
> compression, but I can'y find any in the amanda doc ?
> 
> Some Hints ??
> 
> Thanks !!!!
> 
> -- 
> Frederic Medery
> System Administrator
> 
> LexUM, University of Montreal