System advisor recommendations
The following figure shows an example of a Pending Action List with recommendations to perform the following:
- Decrease the buffer pool BP3 by 46 pages
- Decrease the buffer pool BP4 by 38 pages
The BP3 and BP4 changes enables both buffer pools to continue to operate at peak capacity and makes storage available for use in other pools.
Command ====> _______________________________________________ Scroll ===> CSR_
ADVISOR:PMDZSYSA -- ------------------------------ -- 10/10/17 18:47:22
Pending Action List
Following is a list of all the pending action items for the following DB2 and
interval, with the highest priority items listed first:
DB2 subsystem ID: DEA1
Storage Mode: BALANCE
Interval start: 2017-10-10-18.30.01
Current duration: 15 minutes
VS available . . . : 13538 KB
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Status: Pending Priority: H Advsr: BPM Recmd: DECREASE BP3 by 46 PGS
Action: RULE EXEC Mode: Manual
Status: Pending Priority: H Advsr: BPM Recmd: DECREASE BP4 by 38 PGS
Action: RULE EXEC Mode: Manual
From the Pending Action List, you can perform one of the following actions:
- Click RULE to work with the rule that triggered the recommendation. For more information, see Working with rules.
- Click EXEC to implement recommendations. For more information, see Implement recommendations.
- Click ACKN to acknowledge rules for which no action can be taken. For more information, see Acknowledging rules for which no action can be taken.
Working with rules
A rule describes a condition in Db2. When that condition is met, Pool Advisor triggers a recommendation.
When you click RULE on the Pending Action List panel, the Rule Details panel displays the rule associated with the selected recommendation.
COMMAND ====> _______________________________________________ SCROLL ===> CSR_
ADVISOR:PMDZRULE -- ------------------------------ -- 04/02/22 18:51:45
Rule Details
Rule Identifier: BR3 Rule Version: 6.5 DB2: DEGQ
To control by individual buffer pool: Click here
Rule Description:
A significant I/O rate, sequential access is medium,
virtual pool residency time is less than 30 seconds, and the
system hit ratio is less than 70%.
The action taken by this rule increases the size of the buffer pool by
10% (default), to a maximum of 125% (default) of the original buffer
pool size. These default increment and maximum values can be overridden
by modifying either the SIZE_bpid_INC_PERCENT or SIZE_bpid_INC in addition
SIZE_bpid_MAX values in the variable repository.
Execution Mode: Manual Click here to set automatic mode.
Rule Ignored: No Click here to ignore this rule.
Times Triggered: 0 Click here to reset this counter.
Times Executed: 0 Click here to reset this counter.
Rule Acknowledged: No
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On the Rule Details panel, perform one of the following actions:
- To apply the rule to individual buffer pools, click next to the To control by individual buffer pool field. The following figure shows an example of the Apply rules by buffer pool panel.
- To enable the product to automatically issue the command that is associated with this rule whenever the rule is triggered, change the execution mode to Automatic on this panel.
- To disable triggering a recommendation when the condition that is associated with this rule exists, you can choose to ignore the rule whenever the condition that is associated with the rule is detected.
- To be notified whenever the condition exists, leave the execution mode set to Manual and do not choose to ignore the rule.
The following figure shows Apply rules by buffer pool panel:
COMMAND ====> _______________________________________________ SCROLL ===> CSR_
ADVISOR:PMDZBRUL -- ------------------------------ -- 04/02/22 19:11:09
Apply rules by buffer pool
Rule Identifier: BR3 Rule Version: 6.5 DB2: DEGQ
Rule Description: System hit ratio less than 70%
Click on the Buffer ID value to create an individual rule or delete an
existing individual rule. See product manual for details.
Buffer Times Times Buffer Times Times
ID Aut Ign Ack Trig Exec ID Aut Ign Ack Trig Exec
------- --- --- --- ------- ------- ------- --- --- --- ------- -------
BP0 N N N BP1 N N N
BP2 N N N BP3 N N N
BP4 N N N BP5 N N N
BP6 N N N BP7 N N N
BP8 N N N BP9 N N N
BP10 N N N BP11 N N N
BP12 N N N BP13 N N N
BP14 N N N BP15 N N N
Implementing recommendations
The Command Interface panels enable you to issue commands to the Data Collector, Db2, z/OS system, and OPERTUNE from within Pool Advisor, and to receive feedback from those commands. If Pool Advisor can issue a command to implement the recommendation, click EXEC on the Pending action list to execute the command immediately.
For an example, see the figure in .
You use the OPERTUNE for DB2 component to issue commands to modify ZPARM values.
The following figure displays an example of the Command Interface panel that the product displays when it runs a command:
Command ====> _______________________________________________ Scroll ===> CSR_
ADVISOR:PMDZCMD1 -- ------------------------------ -- 06/19/17 14:26:32
Command Interface
Command Text . . : OPT DHY2 IN(DHY2) SET BP49(+nn) NORESET
Time Submitted . : 14:26:31
Time Completed . : 14:26:32
Command Response :
______________________________________________________________________________
IN(DHY2) SET BP49(+nn) NORESET
BMC31164I DDTL IN(DHY2@DDTL) SET BP49(+nn) NORESET
BMC31164I DDTL DHY2 -ALTER BPOOL(BP49) VPSIZE(1649)
DSNB522I *DHY2 VPSIZE FOR BP49 HAS BEEN SET TO 1649
The Command Interface panel displays the text of the command that was run and any messages that were issued in response to the command. The product issues a message to the SYSTSPRT DD of the DOMPROC whenever Pool Advisor issues a command.
Acknowledging rules for which no action can be taken
Pool Advisor sometimes detects a condition that triggers a rule, but the product cannot implement the recommendation because to do so would breach a limit.
For example, when the EDM pool efficiency drops below 70%, a rule is usually triggered to increase the size of the EDM pool. But if the EDM pool is already at the maximum size specified in the EDMSIZE_MAX parameter, the product cannot implement that recommendation.
In such cases, the product issues a WARNING to let you know that this condition exists, even though Pool Advisor cannot take an action to correct the condition. The product adds an entry to the Pending Action List. The entry remains on the Pending Action List until you acknowledge it by clicking on ACKN (see the following figure). When you acknowledge the item, the status changes to Done. The item remains on the list until the next collection cycle.
Pending Action List
Following is a list of all pending action items for the following DB2 and
interval, with the highest priority items listed first:
DB2 subsystem ID . : DHY2
Storage Mode . . . : BALANCE
Interval start . . : 2021-06-19-14.15.00
Current duration . : 15 minutes
VS available . . . : 22191 KB
______________________________________________________________________________
Status: Pending Priority: M Advsr: BPM Recmd: INCREASE BP49 by nn PGS
Action: RULE ACKN Mode: Manual
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When a recommendation has been acknowledged, but the condition that caused the recommendation remains, the status of the corresponding advisor is changes to NOTICE until the condition is resolved, when the status returns to NORMAL.