Defrag.NSF and DDM are both powerful tools for the Domino administrator. Here's a neat way for a Domino administrator to combine the power of these two great tools to help minimise "wasted" free space by reducing file size in targeted databases on a Domino server. You can use a DDM Database/Scheduled Checks probe to alert you when the amount of unused space in a database is beyond a configured threshold. In the pic below, files in the mail\*.* directory will be monitored for wasted space beyond 1/3 the total size of the database, this valuable disk space can be better used somewhere else on your server.
Now, you will notice there is an option just underneath where you can "Automatically compact the database", the problem with selecting this option is that you cannot specify what style of compact you want and when you have transaction logging enabled the default -b option will be used and there will be no file size reduction, that is where Defrag.NSF will come into play.
Once this DDM probe runs, any database exceeding your threshold setting will trigger the following type DDM document:
With this information we can target the database(s) in question and configure Defrag.NSF to run a Compact -B at the next scheduled maintenance run (yes, the database is small for demo purposes, but you get the point, and it also has one fragment because Defrag.NSF is maintaining this server). This will happen as scheduled without further involvement from the administrator, here are the settings before the maintenance has run.
Now Defrag.NSF will perform this maintenance and defrag the database as an integrated operation as defined by your configured Defrag.NSF schedule:
Here is the result, notice the database size and the number of fragments after the maintenance, compared to the before:
If transaction logging is enabled, best practice dictates you should backup soon after running this style of compact. (DBIID changes)
So there is a very useful way to use these two tools together and harness the power they both offer the Domino administrator, the disk savings are very impressive when this approach is used on even just a few large files with a lot of trapped space. It doesn't take very long at all to set this up and it's a nice surgical approach delivering good results compared to just running Compact on everything in sight (shotgun approach).