We keep 3 version if file exists and 1 version if file doesn't exist.  The retention is 60 days for extra and 180 for only.

From:   Moir,Betsy[SMTP:betsy.moir AT ABBOTT DOT COM]
Reply To:       ADSM: Dist Stor Manager
Sent:   Monday, January 11, 1999 12:08 PM
To:     ADSM-L AT VM.MARIST DOT EDU
Subject:        Re: What standard are people using for backup of their data

Ours is the same as yours except we only keep 3 versions if a file exists.

ADSM-L AT vm.marist DOT edu on 01/11/99 10:08:42 AM
Please respond to ADSM-L AT vm.marist DOT edu @ INTERNET
To: ADSM-L AT vm.marist DOT edu @ INTERNET
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Subject: What standard are people using for backup of their data and

Hello Everyone,

Recently we did a review of what our standard for backup of Data (Files
changing daily or often) and applications were. We currently have ADSM
setup to keep 10 backup versions if file exists and 1 version if file
doesn't exist. The length of time to retain extra backup versions is 30
days and the length of time to retain only backup version is 60 days.

How is everyone else running?

Nelson Reis,
Network Systems Analyst,
Winnipeg, MB, Canada.