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From: Wiley_M_Sanders@cup.portal.com
Newsgroups: comp.os.vms,comp.sys.dec
Subject: Some Questions about 3rd Party ESDI Disk Subsystems
Message-ID: <15216@cup.portal.com>
Date: 1 Mar 89 03:24:46 GMT
References: <2035@nmtsun.nmt.edu>
Distribution: usa
Organization: The Portal System (TM)
Lines: 37

I have decided to replace the puny RD53's in my MicroVaxII with an ESDI
disk subsystem, but I'm having trouble getting straight answers regarding
a couple of questions about DEC service, and compatibility with future versions
of VMS. I'll just go down the list:
   1) All the 'big' manufacturers are going to be DU-driver compatible with
at least versions 4.5 through 5.0-xx of VMS, right? Or am I deluding myself.
I'd include the 'biggies' as all the manufacturers I've heard about, i.e.
Dilog, Emulex, Andromeda, Micropolis, etc.
   2) To optimize backups, I would like to configure the disk (which, within
our budget of $5000, will probably be about 320MB formatted) as several,
smaller DU-devices. This way I can make several, small image backups of the
DU-devices, and not hove to deal with backing up across several TK50's. Does
anybody make such a beast? Dilog says that their model
MQ696 controller is capable of such a thing, but that the DQ696 (a pretty
common model, it seems) is not. Is anybody using a MQ696? What are the tradeoffs
involved - the controllers appear to be otherwise identical (except MQ696page
controls a floppy, too)
   3) Is the term "Category A DEC-service" familiar to anyone? We have DEC-
Service on our machine, and my DEC rep says that only some of the manufacturers
listed in 1) are "Category A", which means that DEC will service them uncon-
ditionally. Other are "Category C", subject to some approval process, and some
are not serviceable at all.
   4) I have not considered a SCSI system because I didn't receive any quotes
back from anyone except Dilog. (SQ-706 controller.) Are SCSI systems going
to be more or less reliable than ESDI? I don't particularly want to be on the
"cutting edge" of Q-bus SCSI technology (ie compatibility problems.) Also,
I have a feeling that SCSI may be a shade slower (we'd have only 1 disk and
no tape hooked up.) Are my assumptions correct?

   Well, if anybody feels like responding, send mail; I'll digest and repost
if anyone else is interested. Thanks in advance for your support...
-w
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