Joe - if the 2 compresion processes are both software, the yes, the output of 
the 2nd compression
will be large than its input.  But if the 2nd compression is being done by a 
tape drive, the drive will be
smart enough to stop the compression if the file grows.  It least that is the 
case for 3590 & 9840.

I am doing exactly what you are doing and I get 19.2 GB on a 9840, which is the 
nominal uncompressed
capacity.

Bill Colwell


At 01:00 PM 1/25/2002 -0500, you wrote:
>Currently running TSM v 4.1.3 on System\390.  Run compression on the client as 
>well as harware compression on Device type Cartridge and 3590.  Ideally this 
>is not the way to go... but we need to run
>compression on the client due to network constraints.  Is it a FACT that 
>running a compression routine 2x will ultimately double the size of the 
>original file?  Where can I find more info on this?
>Any suggestions would be appreciated.
>
>Regards,
>Joe Wholey
>TGA Distributed Data Services
>Merrill Lynch
>Phone: 212-647-3018
>Page:  888-637-7450
>E-mail: joseph_wholey AT ml DOT com

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Bill Colwell
Bill Colwell
C. S. Draper Lab
Cambridge Ma.