RT11 sysgen and disk partitions

[Megan]

>> I believe you want something like the following (my notes aren't handy 
>> at the moment).
>> SET DU0: UNIT=0,PART=0
>> SET DU1: UNIT=0,PART=1 
>> SET DU2: UNIT=0,PART=2
>> SET DU3: UNIT=1,PART=0

>That *does* do it, but I can't figure out where they go.  I could put it 
>in the STARTS.COM file that's loaded by the SJ monitor when it kicks 
>off, but it doesn't appear to have been done that way.  Even if I rename 
>STARTS.COM so it never runs, the drives are set up correctly.

What you need to understand is that RT-11 has a maximum volume size
of 65536 blocks.  Therefore, for volumes which are larger than
this (typically only the DU drives, like RD53 and RD54, or SCSI or
DSSI which act like MSCP devices), the drive is logically partitioned
into units of 32mb each...

The UNIT= argument specifies the physical drive for this controller
(with a sysgen of DU, you can have support for multiple controllers,
so there is a DU SET argument PORT= as well).  The PART= argument
is the partition number on that unit (partitions are numbered beginning
at 0).

So, UNIT=0, PART=0 references the first 65536 blocks on physical
unit 0.

UNIT=0, PART=1 references the next 65536 blocks on unit 0 (if the
volume is not large enough for another 65536, the last partition
is truncated).

UNIT=1, PART=0 references the first 65536 block partition on physical
unit 1.

and so on...

                                        Megan Gentry
                                        Former RT-11 Developer

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| Megan Gentry, EMT/B, PP-ASEL,ST| email: mbg at world.std.com         |
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