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From: LEICHTER-JERRY@YALE.ARPA
Newsgroups: mod.computers.vax
Subject: Re: clusters - update on system disk requirements
Message-ID: <8701221755.AA14738@ucbvax.Berkeley.EDU>
Date: Thu, 22-Jan-87 14:47:17 EST
Article-I.D.: ucbvax.8701221755.AA14738
Posted: Thu Jan 22 14:47:17 1987
Date-Received: Fri, 23-Jan-87 00:54:27 EST
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Reply-To: <LEICHTER-JERRY@YALE.ARPA>
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Approved: info-vax@sri-kl.arpa

In a recent note asking about how much disk space was needed for the system
disk in a Local Area VAXCluster, I said:

    An RD52 is probably just large enough for your system disk, but I'd really
    recommend an RD53.  (Actually, I'm not even sure an RD52 is supported as
    the system disk on LAV boot node.)

I've been informed (by a correspondent who must remain anonymous) that the
situation from the point of view of SUPPORT is as follows:

    A Microvax II serving as a Local Area VAXcluster boot node must have an
    RD54, RA60, RA80, or RA81 as a system disk.  An RD53 system disk (while
    it may work) is not supported.  VAXstation II systems are not supported
    as boot nodes.

He then goes on to say:

    Of course, you and I both know that an RD53 will work.  :-)  As a matter
    of fact, I recently constructed a 4-node Local Area VAXcluster using an
    RD53 on a MicroVAX II boot node; each satellite node had a page and swap
    file on their local disk.  The system disk had lots of layered products
    installed, so it was pretty much maxed out.  Fortunately, we were able to
    switch boot nodes to one with two RA81 disks!

As always, understand what "an RD53 will work" means before deciding to try
that route:  If it works, fine; if it doesn't, or if it works now but breaks
tomorrow, just when you need it; or if it "works" but with unacceptable
performance - you are on your own.  "You break it, you bought it."  (If it
were up to me, I'd buy an RD54 - they are not THAT expensive, compared to your
total system cost, and you can very quickly chew up the difference in the time
you spend trying to get a non-supported configuration to work.  And then you'd
find yourself short of disk space....  Of course, an RA disk would be even
nicer, but then we're talking REAL money.)

BTW, VAXStation II's as boot nodes would almost certainly fall into the "un-
acceptable performance" category in almost any configuration - driving that
screen COSTS.
							-- Jerry
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