> >yup. anyway, compression is off now (and was already set to none
> > when I sent this one).
> 
> Drive hardware compression usually has a mind of its own.  In 
> particular, many drives look at the header, and set the compression 
> on if the tape has ever been written to with the compression turned 
> on, and there is nothing amanda can do about fixing that.  Many 
> drives have an indicator on the front panel called "dc", and if its 
> lit while the tape is being written, then the compression is on.
> 
> The only way I know of to fix such a tape is:
> rewind it
> read out the label to a scratch file using dd
> rewind it again
> turn the compression off with "mt -f device whatever turns it off"
> dd that scratch file back to the tape using the non-rewinding device
> dd at least enough data from /dev/zero to force the drive to 
> flush its 
> buffers.  This will force the drive to turn the header compression 
> flag off and that tape will not be compressed again unless you turn 
> compression back on.
> 
> I noted in a previous msg that your drive is a DDS3.  This drive 
> should be able to stream about 700k/second.  I'd concur that the 
> holding disk isn't enabled, or is somehow miss-configured and that 
> the drive is shoe-shineing the tape due to running out of data and 
> having to back up and restart once the buffer is up to 50% full or 
> so.  Thats a speed killer in addition to causing a lot of wear and 
> tear on both the tape and the headwheel with all that starting and 
> stopping that we suspect it may be doing.

I created a different configuration to backup a remote box, just to make
sure it could me better, and have a look at the results:

STATISTICS:
                          Total       Full      Daily
                        --------   --------   --------
Estimate Time (hrs:min)    0:00
Run Time (hrs:min)         0:11
Dump Time (hrs:min)        0:06       0:06       0:00
Output Size (meg)         317.0      317.0        0.0
Original Size (meg)       317.0      317.0        0.0
Avg Compressed Size (%)     --         --         -- 
Filesystems Dumped            1          1          0
Avg Dump Rate (k/s)       870.2      870.2        -- 

Tape Time (hrs:min)        0:04       0:04       0:00
Tape Size (meg)           317.0      317.0        0.0
Tape Used (%)               2.7        2.7        0.0
Filesystems Taped             1          1          0
Avg Tp Write Rate (k/s)  1249.0     1249.0        -- 

USAGE BY TAPE:
  Label            Time      Size      %    Nb
  fenestra01       0:04     317.0    2.7     1

DUMP SUMMARY:
                                     DUMPER STATS            TAPER STATS 
HOSTNAME     DISK        L ORIG-KB OUT-KB COMP% MMM:SS  KB/s MMM:SS  KB/s
-------------------------- --------------------------------- ------------
arara        /root       0  324630 324630   --    6:13 870.2   4:201249.0

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