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From: dunnett@mala.bcc.CDN (Malcolm Dunnett)
Newsgroups: comp.os.vms
Subject: Emulex TC13 tape controller
Message-ID: <190*dunnett@mala.bcc.cdn>
Date: Sun, 8-Nov-87 09:15:27 EST
Article-I.D.: mala.190*dunnett
Posted: Sun Nov  8 09:15:27 1987
Date-Received: Wed, 11-Nov-87 02:30:54 EST
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The ARPA Internet
Lines: 36


I have a VAX 780 with the following Unibus Configuration

   DW780 -->  DELUA
              Emulex TC13  ( controlling Fujitsu M2444AC tape drive )
              LP11
              Able VMZ32 (3)
              DUP-11
              DZ-11E
              UDA-50

The system is the boot member of a LAVC which has 2 MicroVax II satellite
nodes.

The problem I'm having is that when I do a BACKUP to the tape drive I get
about 40 to 50 "Data Late" errors. These seem to be recoverable and do not
affect the integrity of the save set, but they are annoying.

I assume that the problem comes from the DELUA ( which is closer to the CPU )
"hogging the bus". If this is the case then it seems that swapping the order
of the DELUA and the TC13 might fix the problem. Does this sound reasonable?
Is it likely to cause any problems for the DELUA if it's not first ( DEC
recommends that for "optimum performance" it be first, but they don't specify
how much less than "optimum" is still going to work )

I'd appreciate hearing from anyone who has had experience with a similar
configuration or particularly has solved this problem.

Thanks in advance


Malcolm Dunnett
Malaspina College
Nanaimo, BC Canada

(604)753-3245