On Thursday 19 June 2003 14:19, Tom Brown wrote:
>> Many drives have an led tally on the front to indicate when the
>> comnpressor is active.
>>
>> And no, amanda will not use it, and in fact cannot because once a
>> lock on the drive is obtained, its not released until done. 
>> Turning it off is best done via the dip switch or jumper settings
>> programming of the drive.
>>
>> However, be aware that a tape written to with it on, will override
>> the drives settings until such time as a block 1 write is forced
>> and flushed to the media with the compression turned off.  And
>> drives even vary in that behaviour from production runto
>> production run.  I now have in service some tapes that were
>> originally compressed, and a slightly earlier version of the
>> ctl-96 Seagate drive than the one I started with, and even though
>> the tape labels have been re-written with compression off, the led
>> is on *until* a real data write starts. Those tapes didn't show
>> that little foible until I had to replace the drive with a near
>> identical one.
>
>so if i turn off hardware compression but do not relabel my tapes
> amanda will still think they are being written to using hardware
> aswell as software compression until i relabel them?
>
On DAT tapes here, even a relabel would not defeat the header flags on 
the tape.

Basicly, I have to rewind the tape, use dd to extract the label block, 
rewind the tape, turn the compression and the defcompression off, 
then re-write the label block with dd and flush that from the buffer 
to the tape with another rewind.   Some tapes seems to be double 
stubborn and I had to do the flush with a write of about 10,000 
blocks of /dev/zero.  Those seem to leave the label block compressed, 
but the tape itself is written raw.  But then DAT's can be odd 
critters.

>doesn't sound right and i think i'm mistaken but thought i'd better
> clarify.
>
>Tom

This has been my experience.  That, and a buck will get you a cuppa 
coffee most places. :)

-- 
Cheers, Gene
AMD K6-III@500mhz 320M
Athlon1600XP@1400mhz  512M
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Copyright 2003 by Maurice Eugene Heskett, all rights reserved.