In <7D56E0277E05D211971A0000580119270215CE9B AT msgmsp4.norwest DOT com>, on
11/23/98
   at 02:19 PM, "Glass, Peter" <Peter.K.Glass AT NORWEST DOT COM> said:

>Hello Group,
>We are on ADSM V3-MVS, backing up about 300 clients of various platforms,
>including about 110 or so UNIX platforms. We currently allow clients the
>choice of whether to compress. Most of them do not. In order to slow  the
>rate of DASD growth in our primary backup pool, we are considering forcing
>compression from the Server. We would like to get an idea of  how much of
>an impact we can expect in terms of CPU usage, and backup runtimes. Does
>anybody know of an algorithm that can forecast approximate CPU usage with
>compression turned on? Disk space savings? Or where I can look for this
>kind of information? Any advice or instructive personal experiences along
>these lines would be greatly appreciated. I would at least like to get an
>idea of how much compression I can force without burying the CPU. Also,
>whether the savings in disk space would be enough to make this idea worth
>pursuing. Thank you!

You can expect your mainframe cpu usage to go down but not by that much.
There will be few aggregates to allocate, track in the db, migrate to tape,
etc.

The backup time for a single client will go up, but you should focus on the
total end-to-end daily cycle -- client to server to tapepool -- and tune to
optimize that.

If you turn on compression from the server, I recommend also turning on
compressalways in the client option sets.

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Bill Colwell
Bill Colwell
C. S. Draper Lab
Cambridge, Ma.
bcolwell AT draper DOT com
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