Accessing a VAX tape drive from a S

[Guy Harris]

> but they are useful as file systems.

They can be used as file systems.  This does not necessarily mean they are
*useful* as file systems; are there cases where you would really want to use
one as a file system, and where using one as a file system is better than the
alternatives?

For example, you might want to do so to run a "stand-alone" UNIX to run disk
formatters, or to install your system; however, in 4.0 we have a "memory-only"
UNIX for the former, and have always used the Berkeley "mini-root on the swap
area" hack for the latter, and I've yet to hear of a reason why running UNIX
off a tape would be better.  Note that, while on disks a physical "read" of
4096 bytes will generally just read e.g.  8 512-byte sectors, on tapes a
physical "read" of 4096 bytes will tend to want to read a 4096-byte block; this
may make the Berkeley file system unhappy when run off a tape.