>If you plan to use this drive with the compressor on you should not
ALSO use software compression.  The >tapes capacity for gzipped data
would be closer to 50GB without the compressor.  You would need
>another amtapetype run without HW compression to check the actual
capacity.

Is there a way that I can turn off hardware compression in Amanada? I do
not have that option on the tape loader I use.
 

-----Original Message-----
From: owner-amanda-users AT amanda DOT org
[mailto:owner-amanda-users AT amanda DOT org] On Behalf Of Jon LaBadie
Sent: Tuesday, March 14, 2006 3:52 PM
To: amanda-users AT amanda DOT org
Subject: Re: Tape Type

On Tue, Mar 14, 2006 at 01:23:17PM -0500, Carl Holzhauer wrote:
> Just wanted to post this incase some one else has the same backup 
> device.
>  
> Backup device is a Comapq Storage Works SSL2020 Tapes are Compaq AIT 
> 50GB amtapetype returns the following:
> 
> define tapetype unknown-tapetype {
>     comment "just produced by tapetype prog (hardware compression on)"
>     length 43605 mbytes
>     filemark 0 kbytes
>     speed 5583 kps
> }

The typical 15% loss of native capacity when random data is fed through
the tape drive's compressor due to its expansion of the random data
rather than compression.

If you plan to use this drive with the compressor on you should not ALSO
use software compression.  The tapes capacity for gzipped data would be
closer to 50GB without the compressor.  You would need another
amtapetype run without HW compression to check the actual capacity.

If, OTOH, you don't plan to gzip (SW compression) your amanda dumps and
plan to let the drive's compressor do the job, then the above tapetype
is meaningless.  Depending on the compress- ability of your data, it
could be anywhere from 50 to 150GB.
It will be just a guesstimate.  If amanda keeps filling your tapes,
lower your guess.


-- 
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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Message transport security by GatewayDefender.com
3:54:47 PM ET - 3/14/2006


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Message transport security by GatewayDefender.com
1:03:11 PM ET - 3/15/2006