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From: authorplaceholder@tiger.UUCP.UUCP
Newsgroups: comp.sys.att
Subject: Re: 3B2/300 Disk alternatives
Message-ID: <144800005@tiger.UUCP>
Date: Thu, 4-Jun-87 10:34:00 EDT
Article-I.D.: tiger.144800005
Posted: Thu Jun  4 10:34:00 1987
Date-Received: Sun, 7-Jun-87 02:53:13 EDT
References: <476@moncol.UUCP>
Lines: 61
Nf-ID: #R:moncol.UUCP:-47600:tiger.UUCP:144800005:000:2939
Nf-From: tiger.UUCP!rjd    Jun  4 09:34:00 1987


> The other 300, however, is only equipped with a 10meg disk (it must have
> originally been on a networked file system) which is woefully inadequate
> for its intended use.
> 
> When my Director checked with AT&T about the availability of a lager
> capacity drive, they suggested two options:
> 
> 	1) Add an expansion box at approx. $9000
> 
> 	2) Purchase a SCSI interface and use it to hook the
> 	   300 to a spare CDC 80meg washtub we have. (~$4000)
> 
> As a result, I am left with several questions of my own:
> 
> 	1) Can you really hook a CDC washtub up to a SCSI interface?
> 	   If so, will you need any extra hardware/software.
>  
> 	2) Why can't the 10meg in the 300 just be replaced with
> 	   something larger (like a 70meg Priam)? Is there some
> 	   limitation to what the controller can handle?
> 
> 	3) If you can just drop in the larger (SASI?) drive, then
> 	   what hardware/software changes will need to be made?

   Well, I can't say much about other vendor's drives, but you can simply
unplug that 10 meg drive and plug in a 30 meg drive like your first 3B2.
(By the way, the 10meg is not put into a 3B2 anymore and we, the factory,
have not built any with any less than 30 meg in years.)  I do not know if
it is easy to get that 30 meg drive (it is made by CDC), but it is the exact 
same cable and interface as on your other 3B2.  You may be able to get the
drive by buying an expansion kit that converts a single 30 meg disk model 400
to a dual 30 meg model 400, it also is the same disk.  I am unaware of how to
buy the disk from CDC directly or if you would get the right one if you did.
I would get the 30 meg disk first, if possible, before going to the expansion
module.  You can change to a 72 meg disk in the same manner.  We build models
of 3B2's that use 72 meg formatted (86 unformatted) drives, so your controller
should be able to handle it but the software only knows about a few different
types, you will have to check to see which ones.  My 3B2 (I am running 3B2 Unix
Sys V, release 2.0.4) shows these in the /etc/vtoc  directory:
	Seagate 10M
	Hitachi 72M
	CDC Wren 32M
	CDC Wren II 72M
	Micropolis 72M
	Priam 72M
	Fujitsu 72M
	Hitachi 43M
But I am sure that it will talk to more, these are just the ones that have
vtoc's already determined for them, of course I do not know if AT&T supports
them, you will have to check with your sales rep to find out.
  If your CDC washtub has a single ended SCSI interface (as opposed to a
differential SCSI), it WILL talk to the 3B2 SCSI bus, but it may be up to you to
get it operational software-wise.

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Randy Davis                     		UUCP: ...(ihnp4!)3b2fst!randy
3B2 System Test Engineering
AT&T Oklahoma City Works
All opinions and/or advice stated above are MY OWN, not those of AT&T.
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