Hi Jon,

Thanks for the response.

Definitely DDS4 tapes (we have never had DDS drives before, so
there is no possibility of old tapes getting mixed in).

I tried it without software compression (my first thought too),
results were:

=============================

*** A TAPE ERROR OCCURRED: [[writing file: No space left on
device]].
Some dumps may have been left in the holding disk.
Run amflush to flush them to tape.
The next tape Amanda expects to use is: daily04mon.

FAILURE AND STRANGE DUMP SUMMARY:
  qtechwas0  /var lev 0 STRANGE
  qtechwas1  /opt lev 0 STRANGE
  qtechwas2  /opt lev 0 FAILED [out of tape]
  qtechwas2  /opt lev 0 FAILED ["data write: Connection reset by
peer"]
  qtechwas2  /opt lev 0 FAILED [dump to tape failed]

STATISTICS:
                          Total       Full      Daily
                        --------   --------   --------
Estimate Time (hrs:min)    0:03
Run Time (hrs:min)         2:32
Dump Time (hrs:min)        1:58       1:58       0:00
Output Size (meg)       20069.8    20069.8        0.0
Original Size (meg)     20069.8    20069.8        0.0
Avg Compressed Size (%)     --         --         --
Filesystems Dumped           28         28          0
Avg Dump Rate (k/s)      2905.8     2905.8        --

Tape Time (hrs:min)        2:07       2:07       0:00
Tape Size (meg)         20070.7    20070.7        0.0
Tape Used (%)              60.8       60.8        0.0
Filesystems Taped            28         28          0
Avg Tp Write Rate (k/s)  2704.0     2704.0        --

=============================

So it couldn't even fit 20 GB of uncompressed data onto the tape
?

My info on there being no jumpers to set compression is from the
manual. I suspect that you could be correct in suggesting there
might be DIP switches on the underside of the drive, as I have
commonly seen this too. Unfortunately is is hard for me to
schedule downtime to physically extract the tape drive to look
at, but I will try to get time for this and see what I find.

The "mt" command is supposed to show compression state, but when
I attempt this I get nothing. EG.

[root] # /bin/mt -f /dev/st0 compression
[root] # /bin/mt -f /dev/st0 compression on
[root] # /bin/mt -f /dev/st0 compression
[root] # /bin/mt -f /dev/st0 compression off
[root] # /bin/mt -f /dev/st0 compression
[root] # 

Note the absolute lack of any output after using the command,
regardless of whether I try to turn compression on/off or just
display compression status. The MAN file for mt says:

===============================
 compression
            
  (SCSI tapes) The compression within the  drive  can
  be  switched  on  or  off  using  the MTCOMPRESSION
  ioctl. Note that this method is  not  supported  by
  all  drives implementing compression. For instance,
  the Exabyte 8 mm drives use density codes to select
  compression.
===============================

so it may be that it doesn't support this option (unfortunately
!).


So I'm still looking for answers....   :(



regards,
Tony.


 --- Jon LaBadie <jon AT jgcomp DOT com> wrote: 

> 
> That looks to be the problem, unless ???
> I'm surprised HW compression expands it that much.
> 
> You are using DDS-4 tapes, not DDS-{123} ones right?
> 
> Try it next run without software compression.  25GB should
> have
> no trouble fitting.  HW compression will take it down to about
> the same 15GB that gzip did.
> 
> I think some mt versions have commands that show the
> compression
> state.  And commands to turn it off too.
> 
> Most drives would come with compression on as the default.
> 
> My drive (HP DDS-3) has DIP switches affect the defaults.
> One controls which state it comes up in after at power up.
> The other says whether it can subsequently be changed by
> a software command.  For a while I did not think it had
> any switches or jumpers to affect compression.  Then I
> found out you have to remove the drive from the case to
> access them.
> 
> -- 
> Jon H. LaBadie                  jon AT jgcomp DOT com
>  JG Computing
>  4455 Province Line Road        (609) 252-0159
>  Princeton, NJ  08540-4322      (609) 683-7220 (fax) 

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