On Thursday 12 September 2002 09:54, Kablan BOGNINI wrote:
>Hello,
>
>I am using HP DDS-3 tapes for my backup. I've tried to
>get the correct values for my tape. But tapetype gives
>this result:
>define tapetype HP-DDS3-DAT {
>    comment "just produced by tapetype program"
>    length 9860 mbytes
>    filemark 0 kbytes
>    speed 840 kps
>}
>
>I think this is not correct because I've a DDS-3 125M
>tape with 12GB.
>
>Could someone give me more accurate values for this
>tape or point me to doc ?
>
>Thanks in advance.

That looks as if you have the drives hardware compression enabled, 
which for amanda is a Bad Thing(tm).

When you run tapetype, the source of the data is /dev/urandom.  This 
is not generally compressable data because there is little 
removable redundancy in such data.  And in most cases, the rll 
encoder in the drive will actually expand such data, hence the 
apparent short tape.

This also places an unknown into amanda's idea of what the tape will 
hold as amanda counts bytes sent to the tape *after* any software 
compression has been applied.

So turn off the hardware compression and leave it off forever.  Then 
re-run the tapetype.

Software compression is usually much more effective anyway.  Last 
nights run here put 8370k of real data out to the tape as 3780k on 
a DDS2 120 meter tape, the first time I've actually had a tape 100% 
used.  And its a 46 gig system.

-- 
Cheers, Gene
AMD K6-III@500mhz 320M
Athlon1600XP@1400mhz  512M
99.15% setiathome rank, not too shabby for a WV hillbilly