elvy@harvard.UUCP (Robert Morris) (05/15/84)
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We have been trying to get two tape drives to run under 4.2 UNIX
(both TU-78s) without much luck. For weeks, we have been unable
to open the drive, although it is recognized at boot time. The
DEC man swears that it is functioning properly (although the first
time he did this, it turned out not to have been initialized), but
our machines only recognize one of them.
We have two machines, a 780 and a 750, which are both connected to
the two drives. While both machines recognize both drives at boot,
I can only open drive 0 (drive 1 is not accessible from either
machine). The config file (both machines) contains the following lines:
master mt0 at mba? drive ?
master mt1 at mba? drive ?
tape mu0 at mt0 slave 0
tape mu1 at mt1 slave 0
Has anyone else connected two tape drives to two machines like this?
I welcome advice on how to solve this problem.
Marc Elvy (elvy@harvard) ({ihnp4,allegra}!harvard!elvy)rick@seismo.UUCP (05/15/84)
We have been trying to get two tape drives to run under 4.2 UNIX (both TU-78s) without much luck. For weeks, we have been unable to open the drive, although it is recognized at boot time. The DEC man swears that it is functioning properly (although the first time he did this, it turned out not to have been initialized), but our machines only recognize one of them. We have two machines, a 780 and a 750, which are both connected to the two drives. While both machines recognize both drives at boot, I can only open drive 0 (drive 1 is not accessible from either machine). The config file (both machines) contains the following lines: master mt0 at mba? drive ? master mt1 at mba? drive ? tape mu0 at mt0 slave 0 ---> tape mu1 at mt1 slave 0 Your problem is that you have configured both drives as slave 0. If you change the second drive to be slave 1, everything should work. The driver assumes that all of the slave numbers are unique, regardless of the number of controllers you have. It has an table for mapping minor device numbers to tape unit numbers. What is happening is that the entry in the table is "0" for each unit, despite the fact that they are on seperate controllers. So every reference to mt1 is actually a reference to mt0! You "should" be able to call them both unit 0 since, they are on seperate controllers, but you can't. This problem only shows up if you have two of the same type controller. ---rick
wcs@ho95b.UUCP (59577) (05/17/84)
Someone has already pointed out a bug in your configuration file, but that may not be the only problem. For most of the past year, I have only been able to use drive 0 on my TU78s (2 drives, 1 MT), when I had 4.1BSD running. (USG 4.0 worked fine). A month or so ago, one of my users told me she was using drive 1, but drive 0 wouldn't work. Now they both work. At my last PM, the DEC guy told me he had seen something strange in his diagnostics, but for now I'll leave it unfixed! Bill Stewart BTL-Holmdel