Hello Linda,

It is almost impossible for me to tell you what the ADSM compression
ratios would be for your data. This is because compression ratios
vary, depending on the type of data being compressed. For instance,
text files compress very nicely while files that are already
compressed will not compress very well; in fact, they may even grow!

Even your 3575 won't realize 3:1 compression on data that is already
compressed. A very popular question goes something like, "IBM says
I should be getting 30 GB on a 10 GB tape with 3590 compression, but
my tapes are getting full and they have only 9 - 11 GB of data on
them. What am I doing wrong?" The answer to this is that they are
probably backing up a lot of data that is already compressed (like
.ZIP files) or they are using client compression.

ADSM uses an industry standard compression algorithm so if I had to
give a number, I'd say 2:1 to 3:1, depending on the type of data
you are backing up. Again, though, your mileage may vary!   :-)

I would recommend backing up one or two systems that are
representative of your clients and see what kind of compression
ratios they yield. Then you can try to extrapolate from there.

Sorry I can't be more accurate.

Regards,

Andy

Andy Raibeck
IBM Storage Systems Division
ADSM Client Development
e-mail: storman AT us.ibm DOT com
"The only dumb question is the one that goes unasked."

This is probably directed more to IBM but I would appreciated it if any one
has any info or can point me in the right direction.  (I feel like I am
going around in circle)

I still have questions concerning the Client Compression Rate.

Server: AIX 4.2.1 with ADSM 3.1.5
Clients:  NT ver 2.x.x
          NT ver 3.x.x
Tape Library: 3575-L24

I have client compress on due to network issues.  I need to est. the amount
of tapes needed for roughly 600 PCs.   My question is what kind of compress
rate can I expect using Client Compress.  (I am aware of the compression
ratio for the 3575 - raw 3:1).  I placed a service call but so far all they
have told me is the capacity of the library.  HELP! If I get an answer back
from IBM, I will post it.  Thank in Advanced.