Re:Re: [IDMS-L] migration from PMDC to Performance Monitor

Discussion created by ca.portal.admin on Jul 8, 2009
I have worked with both products and so feel qualified to comment on the
original question and on Josef's reply in particular. PerfMon does show when
there are deadlocks on a resource - the terminal that is holding the
resource is shown beside any other task that is waiting for the same
resource - the User Id is by default displayed with both the offending and
the waiting task. The PerfMon screens are of course user modifiable - so you
can chose to show whichever information you fell is more useful on the
screens that show this information.

When there is a deadlock that is resolved by the system the identities of
the waiting task and the abended task are both displayed - along with the
dbkey when the resource conflict was a dbkey - this is useful in working out
if the problem is an application problem such as with OOAK or NOOAK records,
or a system problem with indexes (or application with too few commits). So
this is a non-issue in terms of PerfMon over PMDC.

PerfMon gives you the option of writing both Task statistics and/or (ADS)
Applications statistics to SMF. You should be careful though because the
SYSTEM statement in SYSGEN gives you the option of writing task stats to the
DDLDCLOG which is both inefficient, and redundant if you are using PerfMon
to write task stats to SMF.

One of the major advantages I found of PMDC was that it runs external to the
IDMS-DC system - so if the CV/DC system is ""hung"" you can get in to poke
around and see what the problem is. With PerfMon if the system is ""hung"" for
certain reasons you will not be able to get in to take a look unless you
have a PerfMon terminal session that is already open for you to use.

I may be wrong here, but I believe that PMDC lets you take a ""dump"" of the
CV/DC system that you can then use the standard PMDC screens to navigate the
system as if it was still running - even though you may have cancelled it.
With PerfMon you would need to take a system SVC dump to forward to CA
where they have tools to help to dig through the system internals - this
tool is available to IDMS users but I am not aware of many people who know
how to use it (outside of IBM, CA and ex-CA employees).

Like many things I think that one tends to prefer the tool that one is
familiar with - I have greater familiarity with PerfMon and that would be my
tool of choice.

There was another post in this thread to do with PMDC terminating tasks that
have exceeded certain limits. This is a standard feature of IDMS-DC and does
not require PerfMon - it's called ""SYSTEM LIMITS"" and can specify the
maximum IO's, DBMS Calls and other criteria - which if exceeded will cause a
task to be abended. There is also a System exit which allows the user to
determine whether or not to override the abend. Use of this feature requires
that SYSTEM TASK COLLECT must be turned on in SYSGEN - there is no need to
do the WRITE if you don't want to.

I will qualify all of this by saying that my PMDC knowledge is several years
out of date, while my PerfMon knowledge is current.

HTH - cheers - Gary

Gary Cherlet

Justice Technology Services

Department of Justice, SA Government

Telephone +61 (0)8 8226 5199

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