Date: January 16, 1996 Time: 12:54
From: Jerry Lawson
ITT Hartford Insurance Group
(203) 547-2960 jlawson AT itthartford DOT com
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We seem to be having a performance problem that has us scratching our heads.
We seem to be having a performance problem that has us scratching our heads.
Has anyone else seen anything like this?
We are running the MVS server at V1 R1 L14. A customer will initiate a backup
(usually an initial backup, but could be a long restore), and the process is
initiated. Throughput seems to be OK, based on what we see on the Kb/sec
indicators. All of a sudden, we will get a message on the client indicating a
TCP/IP failure. On the server, we get an ANR0481 message, indicating that a
client session was terminated after 60 seconds of inactivity. (Message manual
indicates the client was holding a lock. My concern here isn't what we were
holding, but rather "Why have we been sitting there for a minute."
We initially thought that the problem was in a 3172 that we were using for
connections to the mainframe. It was an older model, and it was running at
99% + utilization most of the working day. The network folks think the 3172
is flooded with broadcast messages - ADSM activity is generally low when this
occurs. We addressed this problem by upgrading the 3172 to the new model that
was recently released (90hz Pentium based). (BTW - we are not doing the
TCP/IP offload in this box). However, the next morning after the upgrade
(yesterday) the problem reoccurred. Utilization on the 3172 was in the low
30% range. Diagnostic messages on the 3172 indicate the problem was between
ADSM and the 3172.
On MVS, ADSM runs with a low dispatching priority - underneath batch and TSO.
Is this normal, or should it be above them? Overall MVS utilization exceeds
95% most of the time. TCP/IP's dispatching priority is set very high to
insure it gets what it needs. The 3172 is on a high speed Bus and Tag channel
(4.5 MB/Sec). Does it need to be moved to an ESCON channel?
Can anyone else suggest anything?
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Jerry
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