DB2 for z/OS: Lockmax

Ruediger Kurtz

DB2 for z/OS: Lockmax
Hi everyone,

currently we're discussing the change of LOCKMAX=SYSTEM to LOCKMAX=0.
On the one hand we see the advantages of avoiding lock escalation, but on the other hand we see the possible risk of bringing down the IRLM.
Any comments are more than welcome.

Best regards,
and a Merry Christmas and a Happy New Year to all of you out there

Ruediger

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Michael Liberman

Re: DB2 for z/OS: Lockmax
(in response to Ruediger Kurtz)
Hi Ruediger,

How many locks are expected in you DB2 subsys? Setting the LOCKMAX to 0 does not necessary means that you crash your IRLM.
and as many people on this list said more then once: "IT DEPENDS". :-)





Michael Liberman
DBA Team Leader
IBM Certified Solution Expert
972 54 4685756
www.novelya.com



-----Original Message-----
From: DB2 Data Base Discussion List [mailto:[login to unmask email] On Behalf Of Kurtz, R?diger
Sent: Tuesday, December 21, 2004 1:29 PM
To: [login to unmask email]
Subject: DB2 for z/OS: Lockmax


Hi everyone,

currently we're discussing the change of LOCKMAX=SYSTEM to LOCKMAX=0.
On the one hand we see the advantages of avoiding lock escalation, but on the other hand we see the possible risk of bringing down the IRLM. Any comments are more than welcome.

Best regards,
and a Merry Christmas and a Happy New Year to all of you out there

Ruediger

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gerhard heiss

Re: DB2 for z/OS: Lockmax
(in response to Michael Liberman)
Hi Ruediger,

you can avoid lock escalations, but on the other hand it will be more likely to reach NUMLKUS value for your installation. In that case your job will be terminated by DB2.
First I would try to reduce the total number of locks your application holds. LOCKSIZE PAGE instead of ROW, adding more frequent commits, changing isolation lvl of your plan from RR or RS to CS might be options.

best regards and happy holidays

Gerhard


-----Original Message-----
From: DB2 Data Base Discussion List [mailto:[login to unmask email] On Behalf Of "Kurtz, Rüdiger"
Sent: Tuesday, December 21, 2004 12:29 PM
To: [login to unmask email]
Subject: DB2 for z/OS: Lockmax


Hi everyone,

currently we're discussing the change of LOCKMAX=SYSTEM to LOCKMAX=0.
On the one hand we see the advantages of avoiding lock escalation, but on the other hand we see the possible risk of bringing down the IRLM. Any comments are more than welcome.

Best regards,
and a Merry Christmas and a Happy New Year to all of you out there

Ruediger

---------------------------------------------------------------------------------
Welcome to the IDUG DB2-L list. To unsubscribe, go to the archives and home page at http://www.idugdb2-l.org/archives/db2-l.html. From that page select "Join or Leave the list". The IDUG DB2-L FAQ is at http://www.idugdb2-l.org. The IDUG List Admins can be reached at [login to unmask email] Find out the latest on IDUG conferences at http://conferences.idug.org/index.cfm

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Dave Nance

Re: DB2 for z/OS: Lockmax
(in response to gerhard heiss)
Ruediger,
We do use LOCKMAX=0 as a default for all of our tablespaces, along
with LOCKSIZE=ROW(for a good majority of them). We did raise our NUMLKUS
a bit. We did in the very beginning blow our IRLM out of the water,
prior to getting the worst offenders issuing periodic commits. The main
things we did were to implement a standard routine for processing
commits, that checks a table value each time for the commit frequency.
That allows us to dynamically alter how often a program issues commits.
We, also, created our own precompiler that checks to ensure that there
is a call to the commit routine along with some other standards that we
try to enforce. As long as you attempt to control your locking, you
should not have problems with the IRLM.

Dave Nance
First Health Services, Corp.
(804)527-6841


>>> [login to unmask email] 12/21/04 6:28:45 AM >>>
Hi everyone,

currently we're discussing the change of LOCKMAX=SYSTEM to LOCKMAX=0.
On the one hand we see the advantages of avoiding lock escalation, but
on the other hand we see the possible risk of bringing down the IRLM.
Any comments are more than welcome.

Best regards,
and a Merry Christmas and a Happy New Year to all of you out there

Ruediger

---------------------------------------------------------------------------------
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http://www.idugdb2-l.org. The IDUG List Admins can be reached at
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conferences at http://conferences.idug.org/index.cfm



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