ACT-MSW (activate) will tell the system to stop storing your CDR data on disk and "release" it. COLL-MSW (collect) will tell the system to store the CDR data on disk (up to a configured maximum size) until it is later called for. STOP-MSW will stop it altogether if you don't use it.
However it looks like I was right about being on the wrong track if it really is your config volume being too small, but I have never done the procedure he is talking about, nor do I know how to do it - I have never run up against that problem, but my biggest system only has about 1000 devices configured on it so I may not be big enough. I also have a model 30 that has close to 300 devices on it and I haven't run up against the problem there either. I don't understand how the system would come without enough room for adequate expansion, but I have had systems where there have been limits on the number of certain kinds of devices, groups, trunks, consoles and the like, and I have changed those parameters with no problem, but this is something different.
In my unix/linux experience, the word "volume" is generally synonymous with a disk partition, and something about messing with disk partitions on a system in service, especially the first time, doesn't give me a high level of excitement!!