Ultrix device names

der Mouse mouse at Rodents.Montreal.QC.CA
Thu Mar 22 22:31:00 CDT 2007

> I have a MicroVAX II that is able to boot into Ultrix 4.3 single user
> mode.  If I type "mount" it says that /dev/ra0a is mounted on /.  I
> assume that is my ESDI hard drive since the drives plugged into my
> SDC-RQD11-EC ESDI controller are the only ones plugged into my
> system.

Then that seems like a reasonable inference, yes. :-)

Or rather, it is one of the partitions on that disk.  ra0a is just one
of the (probably) eight possible partitions on ra0.  On some systems,
the partition table was compiled in; on others, it was read off the
disk.  I don't know which Ultrix 4.3 was.

> So, my question is, what would the second drive on that controller be
> called?  Would it be /dev/ra0b or /dev/ra1a?

It would be ra1; the partitios on it would be /dev/ra1a through
/dev/ra1h.  (As far as I can recall, Ultrix did not have any /dev/
entries for the disks in their own right, only for the partitions on
them.  In this respect it was like most other Unices of the time.)

> In other words, what do the "0" and "a" parts of the device name
> mean?  Is "0" the controller and "a" the device on that controller?

Good guess, but not quite.

"ra" is the device type, or, more precisely, the name of the driver
responsible for it.

"0" indicates that it's the first "ra" device (these things are
normally numbered starting from 0).

"a" indicates that you're dealing with partition #1 (partitions are
normally named with letters, a thorugh h in most cases in that era).

You may note this device name does not include any part specifying what
controller ra0 is attached to.  This is normal; Unix device probing
then (and in many systems now as well) hides the path through which a
device is attached to the system, exposing only the end result - the
device itself.

> I also have a TD Systems Viking SCSI controller in the system with a
> CD-ROM drive attached.  What device name would I use for that?

I don't know; I'm not familiar with Ultrix naming conventions for CD
drives.  Probably ra1 or cd0 or some such.

> I'd also like to know how to address that drive from the MVII boot
> prompt so that I can boot directly off of the CD-ROM.

This is another issue entirely; the naming used by the ROMs does not
bear much relation to the names used by Ultrix.  I also don't know that
SCSI controller; it might or might not be bootable, and if not, there
is no name you can use to boot from it.  It probably needs to speak
MSCP to be bootable, though it's been too long for me to remember the
ROM naming scheme for MSCP devices.

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