Hi Paul,

here is the output from the commands:


root@internet:/var/log # mt -f /dev/st0 status datcompression
drive type = Generic SCSI-2 tape
drive status = 436207616
sense key error = 0
residue count = 0
file number = 1
block number = 0
Tape block size 0 bytes. Density code 0x1a (unknown).
Soft error count since last status=0
General status bits on (81010000):
 EOF ONLINE IM_REP_ENroot@internet:/var/log # mt -f /dev/st0
datcompression
Compression off.
root@internet:/var/log # amtapetype -c -e 20g -f /dev/st0
Writing 128 Mbyte   compresseable data:  92 sec
Writing 128 Mbyte uncompresseable data:  95 sec
Estimated time to write 2 * 20480 Mbyte: 30400 sec = 8 h 26 min
root@internet:/var/log #


                                                                                
                                                                    
                                                                                
                                                                    
            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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