Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!ames!ll-xn!adelie!sean
From: sean@adelie.Adelie.COM (Sean Conway)
Newsgroups: comp.sys.dec
Subject: Disk Drive/Controller performance.
Message-ID: <22995@adelie.Adelie.COM>
Date: 8 Mar 89 16:33:01 GMT
Distribution: usa
Organization: Adelie Corp., Cambridge, MA
Lines: 49


I'm going to purchase a MicroVAX 3600 and am wondering about different
disk configuration combinations with DEC and third party drives.  I'll
be running Ultrix.  There are two areas I could use some information:

(1) Performance differences between different combinations Disk Controllers
    and Drives.

    How can you determine the best price/performance ratio using multiple
    drives and controllers?

    For example, does it make sense to buy (2) RA82 and a seperate KDA50 for
    each drive or do you still get the same performance if you were to
    hang both drives off the same KDA50.  Can the Q-BUS handle (2) KDA50 and
    (2) RA82 running at their peak transfer rate?

    What are the variables and algorithms used to come up with these stats?
    
    - Controller Transfer Rate
    - Disk Transfer Rate
    - Bus Transfer Rate

(2) Disk Drive Combination/Disk Partitioning of Third Party Drives.

    Can you buy a MicroVAX 3600 CPU with only Third Party Drives, particurly,
    Emulex 9720-1230 Drive and QD34 crontroller.  The reason this doesn't
    seem possible is that during installation of Ultrix, how does the
    installation software know the partioning scheme of the Emulex
    drive so that it can create the "/", "/usr", "/usr/users", swap, dump.
    and crash space file systems.

    If during the installation, you cannot put "system" file systems on
    non-supported DEC drives, then it means you must have at least one DEC
    drive where all the "system" file systems will live.

    Assuming the above is true, can you later add a Emulex Drive and
    partition the disk?  Is the done by creating your own entry in
    "/etc/disktab"?

I already have four inhouse MicroVAX II running Ultrix so I'm very
familiar with DEC hardware/software.  Any help would greatly be appreciated.

Sean Conway
Adelie Corporation
Cambridge, MASS

{...harvard!adelie!sean}

adelie.Adelie.com