KROON@HGRRUG51.BITNET (Peter A. Kroon, KVI, +31-50-633618) (09/05/86)
Subj: Emulex TC13 (TS11 emulation)
Anyone out there who is using the Emulex TC13 controller to control more
than one tapedrive?
We were using the Emulex TC12 and TC13 controllers on 750 and 780's to
drive Cipher start/stop tapedrives and cache-streamers. The TC12 and TC13
behave like the TS-11 and use the TSDRIVER. No real problems were found
when using a single drive per controller. Now the TC's can control 4 tape
drives simultaneously according to the Emulex specs. To the Unibus they
appear as four completely independent TS-11's (four sets of CSR's etc.)
So we decided to put to Cipher 990 cache-streamers on a single TC13 on a
VAX-11/780 with VMS V4.3. The following problem showed up: if drive A is
performing a long operation like skipping a long file, a normal operation
(write or read a block) on drive B times out after 0.5-1 minute. Emulex
explained, on request, that indeed their TC13 does not support overlapping
operations, which fully explains the problem, although it sounds very strange
to me that one sells a Unibus interface which is clearly intended for the VAX
and PDP world, document it as being able to control 4 drives, and then
explain that it will work only if you use just one drive at the time. Why do
we buy two drives for our VAX????
Anyhow, our Emulex rep installed a second TC13 so that each drive has its
own controller. Now the drives seem to be more independent and overlapping
operations seem to work as expected, but a new problem show up. It appears
that we can crash the system easily by attempting to abort a long fileskip
by control-Y repeatedly. Example:
$ DIR MSA0:
tape has several long files, user doesn't want to wait
and issues ^Y
^Y [interrupt]
$ DIR MSA0:
tape first completes the previous skip operation then
starts with the new DIR command
If you repeat several times, the filenames displayed by the DIR command
become garbled (corruption in MSA0ACP???). If subsequently you do a DIR
command to the other tapedrive, the system crashes in MSA0ACP.
Thanks for any help, suggestions, or similar experiences.
Peter A. Kroon.
(This is the 2nd time I sent this mail. The previous one seems to be
lost somewhere in the BITNET/ARPANET gateway)