On Thursday 08 July 2004 01:32, Alexey I. Froloff wrote:
>* Alexey I. Froloff <raorn@> [040707 14:10]:
>> P.S. Right now I figured how to turn HW compression off (with mt
>> utility) and started amtapetype again...
>
>Thanks to all for your help.  amtapetype finished successfully.
>
>$ /usr/sbin/amtapetype -e 100g -f /dev/nst0 -t "HP-C7971A"
>Writing 1024 Mbyte   compresseable data:  25 sec
>Writing 1024 Mbyte uncompresseable data:  72 sec
>WARNING: Tape drive has hardware compression enabled

Please disable this as it hides the true tapesize from amtapetype AND 
amanda.  amanda can do a much better job of filling up a tape if 
amanda knows how much a tape can hold.  You can use the optional gzip 
compressor on portions of the system to much better advantage in 
terms of achieved compression ratios, and generally can stuff more 
data onto a tape than using the hardware compressor can do.  Here, 
under what would be termed ideal conditions, I've had amanda email me 
and rep[ort that it just put a bit over 12Gb on a 4Gb tape that has 
the last 370megs reserved for something else I'm doing here.

amtapetype uses /dev/urandom as a data source, which will overpower 
the hardware compressor and make the data on the tape larger, by 
maybe 10-15%, than what was fed in, so you do not get a good estimate 
of the tapesize from that effect alone.

>Estimated time to write 2 * 102400 Mbyte: 14400 sec = 4 h 0 min
>wrote 3244032 32Kb blocks in 99 files in 7310 seconds (short write)
>wrote 3244032 32Kb blocks in 198 files in 7666 seconds (short write)
>define tapetype HP-C7971A {
>    comment "just produced by tapetype prog (hardware compression
> on)" length 101376 mbytes
>    filemark 0 kbytes
>    speed 13871 kps
>}

-- 
Cheers, Gene
There are 4 boxes to be used in defense of liberty. 
Soap, ballot, jury, and ammo.
Please use in that order, starting now.  -Ed Howdershelt, Author
Additions to this message made by Gene Heskett are Copyright 2004, 
Maurice E. Heskett, all rights reserved.