IDB2 IQL to capture MBA locks

Products

• SYSVIEW Performance Management Option for DB2 for z/OS
• Database Management for DB2 for z/OS - Performance Suite

Issue/Introduction

Assistance with capturing MBA lock contention events is needed. CA SYSVIEW for DB2 already provides a list of IRLM Lock Contentions (IRLMCNT). Some of these locks are BMC MBA locks that DB2 itself uses to serialize any operation in SCA. The MBA locks can be identified via DBID=49876 (x'C2D4') and OBID = 50029 (x'C36D') - apparently this is "BMC MBA" signature rather than real DBID and OBID. How to produce a dump in case an MBA lock contention happens? This could be a matter of sending a console message or something else that can be captured to produce a dump if needed.

Environment

Release :

Component : CA Insight Database Performance Monitor for DB for z/OS

Resolution

The following IQL Exception was created to address this need:

IRLMBMCL: TRACE (COLFMT=YES SL=1 LS=160)

<<*IRLM-CONTENTIONS
'IRLMBMCL'
'Buffer Manager SCA MBA Lock'
'Subsys=' SUBSYS
'Plan=' HOLDER-PLAN-NAME
'DBID=' HOLDER-DBID
'OBID=' HOLDER-OBID
WHERE HOLDER-DBID = X'C2D4' AND HOLDER-OBID = X'C36D'
>>

TITLE = ('BMC MBA Lock Sniffer')
INTERVAL 5 SECONDS
DATASHAREABLE
TERMINAL (panel=DBGSDIC,help=DBGRLKCC,nodata=DBGNTRA)
EXCP
;
This request can be started and it will generate an exception if there is an BMC MBA lock contention.

You also need to define an IQL Exception called "IRLMBMCL". In the exception definition you can request that a WTO (Or OPS event) be issued. You can also define an operator command to be issued directly. If you use a WTO, you can then react to the WTO by generating a dump or whatever you like.