Ultrix device names

[Roger Ivie]

On Thu, 22 Mar 2007, David Betz wrote:
> 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. So, my question is, what would the 
> second drive on that controller be called? Would it be /dev/ra0b or 
> /dev/ra1a? 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?

0 is the drive and a is the partition.

However, bear in mind that (this being Unix) the *real* magic is done in
the directory entry. If you take a close look, you'll see that /dev/ra0a
is a block special device with two parts: the device number (index into
the devsw[] array) and unit number. You can create a special file with
*any* name that maps to the same device as /dev/ra0a.
-- 
roger ivie
rivie at ridgenet.net