[TUHS] pre-FSCK days

[Ronald Natalie]

Yep I remember those days.    In order to get signed on to work in the UNIX computer center I had to demonstrate I knew the structure of the V6 filesystem and what icheck and dcheck reported, what the common errors were, and how to fix them.

Two things changed.   First FSCK was wriiten, but even to make that useful, some fixes were done to the ordering of operations in the kernel so that the file system wouldn’t be left in a degenerate state after crashes.    Before these changes were made inode link counts less than the number of directory links and dups in free were common.   After the changes to the FS, you’d get missing blocks and a few 0-0 inodes (or ones where the links count was higher than the links).    These while wasteful were not going to cause problems.