Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!bionet!apple!motcsd!xdos!doug
From: doug@xdos.UUCP (Doug Merritt)
Newsgroups: comp.sys.amiga.tech
Subject: Re: filesystem links (was: yet another 1.4 request)
Message-ID: <397@xdos.UUCP>
Date: 30 Jun 89 16:00:51 GMT
References: <392@xdos.UUCP> <8489@killer.DALLAS.TX.US>
Reply-To: doug@xdos.UUCP (Doug Merritt)
Organization: Hunter Systems, Mountain View CA (Silicon Valley)
Lines: 40

In article <8489@killer.DALLAS.TX.US> elg@killer.DALLAS.TX.US (Eric Green) writes:
>The problem is that there is a seperate file system process for each
>mounted device on the Amiga, Doug, so it's hard to do cross-device links [...]
>Needless to say, such a filesystem would be totally different from the
>current filesystem, whereas soft links can be plugged into the current
>filesystems with little trouble.

True. But let's call that an implementation detail. :-)

>$ least Unix V.4 will have a process FS, again an old concept but not one
>$ being considered for AmigaDos yet.
>  
>Are you saying that under Unix V.4 that filesystems run as a process?
>That's been true from the earliest versions of AmigaDOS... it's

No, I mean that processes will have entries in the file system. The
idea being that the generalization of a file system is that it's a name
space that can be conveniently used to find data, and "pointers" to
processes are a handy thing to find there, too. Just like it's been
handy that Unix has always had file system entries for kernel memory,
user process memory, physical devices, etc, in addition to "regular files".

Mach, on the other hand, has user-installable file system servers,
somewhat like AmigaDOS.

>Of course, under Unix V.4 each filesystem will have only a single
>process, while under AmigaDOS each mounted device has a filesystem
>process... but I don't want to second-guess the tradeoffs between the
>two approaches. 

I don't understand your comment, probably because I don't know what V.4
provides in this area. Perhaps you mean that V.4 has a process per
filesystem, which is to say per logical device (disk partition), whereas
AmigaDOS has a task per physical device? Hmmm, no, not true of AmigaDOS,
you can mix slow and fast file systems on a single disk.
Care to clarify?
	Doug
-- 
Doug Merritt		{pyramid,apple}!xdos!doug
Member, Crusaders for a Better Tomorrow		Professional Wildeyed Visionary