Object Space Used

Q. I am creating a utility which tracks my disk usage by library for purchase and usage projections. The difficulty is that when I add up all the object sizes, the total is not consistent with the percentage of disk used (in the WRKSYSSTS panel).

The difference is not always the same; the variance ranges from 5 to 12 percent. Does this have anything to do with those spool files that don't go away until the seventh IPL (or whatever that is)?

I have used both DSPOBJD to an outfile and the operating system API to retrieve object size (and they seem consistent with each other).

A. There are loads of "hidden" DASD utilizations all over the place on the AS/400. For starters, you will notice that the percentage you can't account for drops following an IPL. OS/400 does not clean up after itself in several areas. Spool files are just one example. I've found others which just leave some DASD space unusable until the next IPL.

Another is the microcode library. You can't access it and you can't size it. I went through this exercise when I first got my new model B40 years ago. I could not reconcile the amount of DASD I purchased with what the system was telling me it had. When I asked IBM about it, I was told that I'd just have to trust that the 3GB of disk that I paid for was all there.