Path: utzoo!utgpu!attcan!uunet!lll-winken!lll-tis!helios.ee.lbl.gov!pasteur!ames!think!bloom-beacon!spdcc!lexicon!rk
From: rk@lexicon.UUCP (Bob Kukura)
Newsgroups: comp.sys.next
Subject: Re: Mach features? (Re: Paging and swapping to a removable disk?)
Message-ID: <315@lexicon.UUCP>
Date: 21 Oct 88 16:03:20 GMT
References: <12670001@eecs.nwu.edu> <3924@encore.UUCP> <3352@pt.cs.cmu.edu> <73838@sun.uucp> <4200@boulder.Colorado.EDU>
Organization: Lexicon, Inc., Waltham, MA
Lines: 38
In-reply-to: bernard@boulder.Colorado.EDU's message of 20 Oct 88 23:48:34 GMT

In article <4200@boulder.Colorado.EDU> bernard@boulder.Colorado.EDU (Bernie Bernstein) writes:

   Oh yeah, and let one CPU manage the paging for the entire network.
   Then we can see some real wild thrashing.:->

   I think what is necessary is paging to the local disk.  It should be a
   fast one, so if the seek rates on the optical disk are above 30ms, then
   perhaps a Wren (16.5ms) or some other traditional hard disk should be used.
   Otherwise, we can keep the optical disk in and go along with Ralph's
   hypothesis:  don't let the disk out unless we're ready ...


Since MACH can swap to free space on any filesystem, I would set up
NeXT machines in an NFS network environment as follows:

* boot from a network server

* mount root, /usr (and /var) via NFS, with all NeXT machines sharing
the same /usr

* install a small fast winchester disk on each machine mounted as /tmp
and swap on this

* mount the floptical disk as /usr/user with some hack so that it is
automatically mounted when it is inserted and unmounted when it is
removed


This setup seems pretty optimal to me in terms of performance,
administration, user convenience, and security.  Swapping and most
file writes of a temporary nature are on the winchester, so they are
fast and don't wear out the floptical disk.  All system software and
educational software is centrally maintained, with no system
configuration local to the machine.  The /tmp filesystem could be
recreated each time the machine boots.  Users take their own files and
software with them on their floptical disks.
-- 
-Bob Kukura		uucp: {husc6,linus,harvard,bbn}!spdcc!lexicon!rk
			phone: (617) 891-6790