Newsgroups: comp.os.minix
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: switching file systems
Message-ID: <1989Oct6.170630.6287@utzoo.uucp>
Organization: U of Toronto Zoology
References: <24987@louie.udel.EDU> <2453@ucsfcca.ucsf.edu> <1989Oct5.181148.8229@utzoo.uucp> <2461@ucsfcca.ucsf.edu>
Date: Fri, 6 Oct 89 17:06:30 GMT

In article <2461@ucsfcca.ucsf.edu> root@cca.ucsf.edu (Systems Staff) writes:
>> Filesystem switches have many uses other than filesystem conversions.
>
>Yes, but usually only on research or other special purpose systems

Um, you obviously aren't acquainted with some of the things that can be
done with them.

(And you've forgotten that teaching -- Minix's raison d'etre -- is very 
definitely such a "special purpose".)

>(in this context we are only talking about filesystems for the same
>device population -- not like the differences due to mixed read/write
>and read-only media).

Even if you restrict it to the same device population, there is much to
be said for being able to optimize different filesystem for things like
speed vs. space.  More to the point, though, the big win of filesystem
switches is being able to make filesystems out of things that *don't*
"really" look like filesystems.  Disks in highly nonstandard formats (like
MSDOS or TOS).  Network connections with file servers on the other end.
The process table in the system ("/proc" is superior to "ptrace" in every
way).  User programs that present services that want to look like files.

>Not to mention the problem of the user level incompatibilites which
>would be introduced (which your comments did not address) ...

Uh, *what* user level incompatibilities?  There is no reason for user
programs to see any change whatsoever, except having more facilities
available.
-- 
Nature is blind; Man is merely |     Henry Spencer at U of Toronto Zoology
shortsighted (and improving).  | uunet!attcan!utzoo!henry henry@zoo.toronto.edu