On Thursday 19 June 2003 11:51, Ean Kingston wrote:
>I couldn't find this one in the list archvies, so here it is.
>
>I'm using 40GB DLT tapes (according to the label). Despite what the
> comment produced says, I used the non-compressed device. I didn't
> give it an estimate for the tapesize.
>
>Writing 256 Mbyte   compresseable data:  34 sec
>Writing 256 Mbyte uncompresseable data:  105 sec
>WARNING: Tape drive has hardware compression enabled
>Estimated time to write 2 * 1024 Mbyte: 840 sec = 0 h 14 min
>wrote 1102644 32Kb blocks in 3372 files in 21817 seconds (short
> write) wrote 1101228 32Kb blocks in 6756 files in 29828 seconds
> (short write) define tapetype HP-DLT1e {
>    comment "just produced by tapetype prog (hardware compression
> on)" length 34499 mbytes
>    filemark 13 kbytes
>    speed 1399 kps
>}

And it appears the hardware compressor being on cost you 5.5 gigs.
The various 'tapetype' programs all use the output of /dev/urandom as 
the data source, and the output of /dev/urandom is not compressible, 
and will in fact grow by about the percentage you see above in being 
passed thru the hardware compressor.

As others have noted Ean, you can turn it off, but this must be done 
for every new tape thats inserted as the recognition phase of the 
drive will turn it back on when the tapes are changed.  Such info as 
how to turn it on/off should be on the drive makers web page.  To 
your vendor its obviously not a very high priority to obtain that 
info for you else he would have fired up a browser and found it on 
the spot.

-- 
Cheers, Gene
AMD K6-III@500mhz 320M
Athlon1600XP@1400mhz  512M
99.26% setiathome rank, not too shabby for a WV hillbilly
Yahoo.com attornies please note, additions to this message
by Gene Heskett are:
Copyright 2003 by Maurice Eugene Heskett, all rights reserved.