IBM BS029ML - WebSphere Portal Server Self Help Manual page 109

When the PAC configuration is to be persisted, the datastore persistence layer is called to
pass the configuration data to the portal database. The Portal Access Control runtime
decision module has to retrieve the persisted permission data through the datastore
persistence layer. In order to reduce the IO traffic to the datastore, the portal architecture
adopts a fairly sophisticated cache management system.
The multi-level fine-grained controls over PAC caches gives the portal administrator a lot of
flexibility and opportunities in tuning the performance. On the other hand, improper PAC
cache settings could adversely cause serious performance degradation to the portal system.
In WebSphere Portal Version 6, the PAC and other cache configurations are managed by
CacheManagerService. A default set of configuration parameters are presented in
CacheManagerService.properties in <portal_root>/shared/app/wp.services.properties.jar.
These settings can be customized through "WP CacheManagerService" in the WebSphere
Administrative Console by selecting Resources → Resource Environment Providers →
WP CacheManagerService.
External
Access Control
SPI
Figure 4-4 Portal Access Control components
Some suggestions on tuning the PAC caches are summarized below:
Keep the access control configurations as simple as possible.
Minimize the number of user groups.
Minimize the number of different groups to which the users belong.
Avoid nested group hierarchies and depth of the nested groups.
Avoid doing access control administration while the system is under heavy load.
Limit the use of external access control.
Access Control Access Control
Runtime
Access Control Access Control
Service Commands
Access Control
Config Service
Access Control Engine
PAC Cache
Data Store
Portal
Database
Chapter 4. WebSphere Portal security
Admin
PAC - API
Internal
Configuration
API
PAC Implementation
Persistence Layer
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