> Does anyone have deeper thougths about the number of versions of client-
> files that should be maintained on the server as the default.
> We use 3 just because it sounds pretty save.

We think it depends on what you are trying to protect.  For some
servers, we require 2 weeks (so use 14) ... on most we use 5/2
(exists/deleted).

> But from the point of view of backup, one should say that 1 version would
> be sufficient. (We use ADSM V2 with copy storage pools).
> Keeping 1 version would, of course, save a  lot of DB and stgpool space,
> but, what would be the impact from other point of view, like risk
> management?

We would like IBM to provide us with a utility to estimate what the
current inactives cost us in terms of database (mostly) and tape:

   Files/space with noinactives:    nnnnn/mmmmm
   Files/space with 1 inactive:     ...
   ...              2 inactives:    ...
   etc.

I'd suggest that if you have only 3 versions, then you have LITTLE
space tied up in old versions.  For example, during a "normal" day,
I'll change 125 files out of 8,000 on my PC.  But just about the same
files are changed each day.  So less than 2% of my files change.  I
could double my versions and it would be little more than background
noise as far as database and tape space go.

Additionally, a "good" file is often replaced with a worthless
version. If a backup or two goes by before I discover the problem, I'd
better have at least three versions in ADSM!  And if I ever want to
(or expect that my clients might) have another life with other
priorities, we'd better provide more versions than that.

Regards,

Wayne T. Smith
Systems Group -- CAPS        internet: wts AT maine.maine DOT edu
University of Maine System   BITNET/CREN: WTS@MAINE