Bill,

        Compression is, obviously, very dependent on data type.  I have
achieved up to 80% compression on database dumps (Sybase) with large amounts
of blank space.  Compression of already compressed files can result in
backup failures unless you use the "compressalways=yes" option because
compression may actually increase the files' size.  It will reduce the
network volume, but it can be client CPU intensive to compress the data and
may result in somewhat slower backup speeds.  I have heard reports that
decompression is more efficient than compression, but haven't tried to
verify them.  There is also the issue of hardware compression on tape
volumes - the same as compressing a compressed file; it may grow.

        Most of my clients do compression because we bill them for our TSM
service based on the amount of data transferred.  Compression gives them
some relief when paying their bill.

        Gary L. Ison
        Governor's Office for Technology
        101 Cold Harbor Drive
        Frankfort, Ky.   40601
        Phone:  (502) 564-8724
            Fax:  (502) 564-6856
E-mail: Gary.Ison AT mail.state.ky DOT us <mailto:Gary.Ison AT mail.state.ky 
DOT us>