Hi,
Prune and purge is something which don't really need to run a on a daily basis.
You can set the period of prune and purge to run for every 90 days or 180 days, depending on the sze of arcserve's database. The recommended size is about 1.5 gb to 2 gb. Accordingly you can decide on the frequency of prune & purge.
The basic difference between auto-pruning and auto-purging is, auto-pruning maintains the file astpsdat.db, where the auto-purging takes care of the rest of files in the database folder.
Hope this helps...
ArcserveFreek "Patience, persistence and perspiration make an unbeatable combination for success."