VS II: it'll give you fits! (AOS/VS II operating system)

When you live with someone you get to know them pretty well. For the past six months, I've been "living" with AOS/VS II. We've actually been "dating" for over a year, but during the last several months we've become especially close. Sometimes too close.

You see, during that time I've been developing Disk [underscore] Pak Online, a disk optimization utility for VS II available from Eagle Software. The online utility reorganizes files on the disks while running transparent to user applications.

I think the folks at Data General did one heck of a job when developing VS II. The file system underwent a major overhaul, enhancing its flexibility and fault tolerance. The most visible are mentioned here.

Fit file. The "fits" I mentioned in the title is simply meant as a punny reference to the fit (File Information Table) file. There is one fit file for each LDU. It holds the filestatus type of information that used to be stored in the directories with the filenames on VS Classic.

The default element size of the fit file is four blocks, but can be set with Disk Jockey when the LDU is formatted. One block of the fit file holds …