Overview of background advisors
The following individual component advisors monitor pool advisor storage resources:
- Buffer Pool Advisor (one for each buffer pool)
- Group Buffer Pool Advisor (one for each group buffer pool)
- EDM Pool Advisor
- RID Pool Advisor
- Sort Pool Advisor
- Dynamic Statement Cache Advisor
- Virtual Storage Constraint Advisor
- Real Storage Constraint Advisor
The background component advisors monitor the storage resources constantly and compare the statistics that they gather against a set of rules that define conditions that warrant attention. When a condition that is identified by a rule is detected, the individual advisor that detected the condition checks the parameter values for the resource and sends a recommendation to the system advisor.
When System Performance or Pool Advisor recommends that you change the size of storage pools or what the maximum and minimum thresholds should be, the following values are used by default:
- Increase resource by 10% of ZPARM value
- Decrease resource by 10% of ZPARM value
- Maximum total increase of 25% of ZPARM value
- Maximum total decrease of 25% of ZPARM value
If the default values are not suitable to your environment, you can use parameters to modify the values. Parameters allow you to define the incremental amounts that storage resources can be increased or decreased and the minimum and maximum limitations.
The system advisor evaluates all information that is received from the component advisors and determines (with the data from the virtual storage advisor) whether the recommendations received can be implemented without an adverse effect on other resources.
The system advisor considers the overall storage constraint and evaluates the effect of an increase in the size of the EDM pool on other storage resources. The system advisor also checks the EDM pool parameters to see if the maximum size parameter would be exceeded by the recommended action. For more information, see EDM pool.
If the system advisor decides to honor a recommendation, it is added to the Pending Action List. For more information, see System-advisor-recommendations.
The following figure shows the relationship between the advisors, Db2, and reports.
If you find that the recommended changes based on these default values are no longer appropriate (for example, because of changes to ZPARM values), you can modify the default values.
The variable repository provides a method for editing parameter variables through a series of panels. The panels outline all of the variables, giving you the opportunity to edit any or all of the values.
For more information about parameter variables and rules for instructions about changing parameter values, see Parameter-variables-and-rules.
The ADVISOR button is you window on background advisors. For more information, see Advisor-alerts.