Problem adding a third disc drive to a Sun 3/80 server

[Per Elmdahl]

I am having a problem adding a third disc drive to a Sun server. If you
can give me a hint about how to solve the problem, please reply via
e-mail.

We have a Sun system with the following configuration:

The server is a Sun 3/80 with 12 Mbytes of RAM. Connected to the SCSI
connector is a 150Mbyte tape drive (Sun brand), and two shoeboxes. The
tape drive set to SCSI address 4. The shoeboxes contain one CDC Wren IV
drive each. They are set as sd0 and sd2. At the last shoebox there is an
external SCSI bus terminator. This setup has been working correctly for
several months.

On this setup we are adding a third dics drive, a Hitachi DK515C-78, by
removing the external terminator and adding the cable to the drive. The
drive contains a terminator, so the external is not needed. The disc is
formatted, mkfs:ed, used, and all is OK........ BUT SUDDENLY...

sd2:     sdtimer: I/O request timeout
         Snap shot(HEX): state = 0, err=0, stst=0, int=20, substate=a0
         ESP xcnt_lo= 0, hi= 0, cmd= 44, cur_target= 0
         flag= 0, stat= 10, step= c4, int= 0

         num_dis_target= 1  scsi_stat= 0  scsi_msg= 0
         DVMA_stat= 10, addr= fff06400  count= 0 (0)
         cdb=   8  3  b1  90  2  0
sd2e:   write failed, blk 53122 (rel. blk 13792)
        sense  key(0x0): no sense
sd2h:   <now we get an endless list of the previous message with
         different block numbers...>

The sd2 disc gets corrupted and the files edited at the moment vanish of
course.  What is wrong? If we disconnect the new drive, everything is OK
again.  Do we have to change anything inside the shoeboxes? When trying to
run format with the new disc installed, format sometimes does not find sd2
any more.

        Per Elmdahl, per at lysator.liu.se    Lysator Computer Club.