Checking global resource serialization (GRS) resource contention
To check GRS resource contention by displaying GRS enqueues and latch usage
on all machines in the sysplex, issue either of the following MVS™ commands, as
shown in Figure 1:Figure 1. Examples of DISPLAY GRS commands
D GRS,C
D GRS,RES=(SYSZLOGR,*)
A normal response looks like one shown in Figure 2:Figure 2. Example of a normal response from a DISPLAY GRS command
D GRS,C
ISG020I 12.06.49 GRS STATUS 647
NO ENQ CONTENTION EXISTS
NO LATCH CONTENTION EXISTS
D GRS,RES=(SYSZLOGR,*)
ISG020I 14.04.28 GRS STATUS 952
NO REQUESTORS FOR RESOURCE SYSZLOGR *
A response showing GRS contention is shown in Figure 3:Figure 3. Example
of a GRS command showing contention
This example shows which tasks have exclusive enqueues on the log streams
and which tasks are waiting for them. It is quite normal for enqueues and
latches to be obtained, occasionally with contention. They are indications
of a problem only when they last for more than a minute or so.
Long term enqueuing on the SYSZLOGR resource can be a sign of problems
even if there is no contention.
You can choose to display only those log streams exclusively enqueued on,
or being waited on, by DFSMStvs jobs in the sysplex. Issue the MVS command shown
in Figure 4:Figure 4. Example of a GRS command to display log streams with an exclusive enqueue
D GRS,RES=(SYSDSN,*)
A typical response to this command looks like the example in Figure 5: Figure 5. Example of output from a GRS command to display log streams with an exclusive
enqueue
S=SYSTEMS SYSDSN ANTHEM.SPFLOG2.LIST
SYSNAME JOBNAME ASID TCBADDR EXC/SHR STATUS
SY02 ANTHEM 002B 009FFBF8 EXCLUSIVE OWN
S=SYSTEMS SYSDSN ASM.SASMMOD1
SYSNAME JOBNAME ASID TCBADDR EXC/SHR STATUS
SY03 XCFAS 0006 008FFBF8 SHARE OWN
SY03 LLA 0017 008FFBF8 SHARE OWN
SY01 XCFAS 0006 008FFBF8 SHARE OWN
SY01 LLA 0017 008FFBF8 SHARE OWN
SY05 XCFAS 0006 008FFBF8 SHARE OWN
SY05 LLA 0017 008FFBF8 SHARE OWN
SY04 XCFAS 0006 009FFBF8 SHARE OWN
SY04 LLA 0017 009FFBF8 SHARE OWN
SY02 XCFAS 0006 009FFBF8 SHARE OWN
SY02 LLA 0017 009FFBF8 SHARE OWN
S=SYSTEMS SYSDSN ASM.SASMMOD2
SYSNAME JOBNAME ASID TCBADDR EXC/SHR STATUS
SY03 XCFAS 0006 008FFBF8 SHARE OWN