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From: mod-os@sdcsvax.uucp
Newsgroups: mod.os
Subject: kernel vs user space file servers
Message-ID: <2455@sdcsvax.UCSD.EDU>
Date: Tue, 13-Jan-87 16:32:25 EST
Article-I.D.: sdcsvax.2455
Posted: Tue Jan 13 16:32:25 1987
Date-Received: Wed, 14-Jan-87 01:19:04 EST
Sender: darrell@sdcsvax.UCSD.EDU
Reply-To: ast@botter.cs.vu.nl (Andy Tanenbaum)
Organization: VU Informatica, Amsterdam
Lines: 30
Approved: mod-os@sdcsvax.uucp

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In article <2438@sdcsvax.UCSD.EDU> henry@utzoo.uucp writes:
>
>Alternatively, does it matter?  It's all very well to say that your file
>system is in a user-state server rather than in your kernel, but your users
>are probably just as dependent on every little detail being right.  To make
>user-state servers more than an irrelevant implementation detail, the user
>must be offered a choice of servers AND IT MUST BE EASY TO WRITE A SERVER!
>Or at least, not impossibly hard.  If writing a server is as touchy a job
>as writing the equivalent inside the kernel, the wonderful flexibility will
>get little use. 
>

Amoeba has three user-space file servers:

1. A UNIX-like file server (actually the MINIX file server).

2. The FUSS file server, which is a research type file server with atomic 
   commit (see 10th SOSP).

3. A dumb, but very fast file server.

File servers are not something that every user can write, but I certainly
want the flexibility of having various gurus and researchers being able to
write new file servers whenever they want to.    Writing a file server is
a fair amount of work, but is not unreasonable for a Master's thesis.

Andy Tanenbaum
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