One thing to remember is that deleted files, even if never purged, will be overwritten if space is needed for normal "non-deleted" files. Take this example:
10 GB Volume. 5 GB FULL. 5 GB of Deleted Files, ready to either salvage or purge.
Say you copy 4 GB's worth of new files to the volume, NetWare will not report out of space. Instead, it will reclaim 4GB and give it to the new file you're copying. So as a result, you'll have 9GB full and 1GB worth of purgable files.
So if you are in a situation where you need to free up some space (like if you're getting out of space errors) Purging isn't really going to help. A lot of people will immediately take that route, but it's pretty much useless.
Although I do have to qualify myself here, because someone is definitely going to yell at me.. Sometimes it depends on your specific application or platform. There are some cases where the CLIENT might think the volume is out of space, and purging it will make the CLIENT think more is available. If it checks first before copying, and takes into consideration the deleted files space usage, then it might prevent a file copy based on that logic. But from a server standpoint, it doesn't really matter. If there are purgable files, and it needs space, it will reclaim the space and write the new file.
As far as setting the parameter "SET IMMEDIATE PURGE OF DELETED FILES=ON", I disagree with the logic, from a business perspective. Having salvagable files is a nice safety features and can save your butt when users do stupid things like accidentally delete a database. Or when people try to delete their porn so they don't get caught but don't know it's still there.
It's easy enough to schedule a cron job to automatically purge the files on a weekly or monthly basis if you want to keep things clean and tidy.
That is my dissertation for the day. Don't expect another one till next weekend
Marvin Huffaker MCNE, CNE
Marvin Huffaker Consulting