Partitioning a HD with RT-11 V5.3

From: CLASSICCMP_at_trailing-edge.com <(CLASSICCMP_at_trailing-edge.com)>
Date: Thu Oct 15 21:15:05 1998

>I realized something, even if I do get this working, I'm going to need to
>partition one of the ESDI hard drives since they are to big for RT-11,
>according to the WQESD controllers documentation the partitions need to be
>30Mb or smaller. My smallest ESDI drive is 150Mb.
>How do I go about partitioning the drives? Unfortunatly my Doc set is for
>V3, so I can't RTFM on this one.

Since you've got a WQESD, you've got two choices with respect to
partitioning:

1: Hardware partitioning.
    Partition your 150 Mbyte drive into multiple 65536-blocks drive
    through the WQESD firmware. You don't need to do a reformat from
    scratch; just redefine the disk structure and write it to disk.

2: Software partitioning.
    Partition from RT-11. Assuming your drive is at LUN 0, you
    already have the default mappings SET DU0:UNIT=0 and SET DU0:PART=0.
    The "UNIT" refers to the MSCP LUN of the drive, and the PART
    refers to the software partition number.

    Map DU1: to be the second logical partition on the first MSCP
    LUN with SET DU1:UNIT=0 followed by SET DU1:PART=1.
    Continue on up until you've used up all the disk. Each PART
    refers to a logical partition on disk, each of which is 65536
    blocks long (except for the last one, which is whatever is left
    over.) Of course, only the first 65535 blocks of each partition
    are directly usable, given RT-11's block numbering scheme.

    SHOW DEV:DU will show you the current partitioning.

    Keep in mind that if DU is your system disk, you'll have to do
    a reboot to reload the driver with the "new" partition settings
    before they'll go into effect. (You wouldn't believe the number
    of RT-11 5.7 field test sites who complained "partitioning doesn't
    work" when they simply failed to reboot after the SET DU's! This
    has been in the manuals for over a decade!) After rebooting, INIT
    DU1:, etc., and away you go!

Since you *do* have the WQESD, I heavily recommend that you do your
partitioning at the WQESD level and not at the RT-11 level. This way
all your partitions will be hardware bootable. If you do the
partitioning through RT-11, the resulting logical partitions won't
be hardware bootable.

A neat tool (hey, I wrote it, I think it's neat) for looking at MSCP-
level stuff under RT-11 is the DUSTAT program, available from

ftp://sunsite.unc.edu/pub/academic/computer-science/history/pdp-11/rt/dustat/

 Tim Shoppa Email: shoppa_at_trailing-edge.com
 Trailing Edge Technology Voice: 301-767-5917
 7328 Bradley Blvd Fax: 301-767-5927
 Bethesda, MD, USA 20817
Received on Thu Oct 15 1998 - 21:15:05 BST

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