In policy server logs, I noticed that log :
[12236/13212][Fri Feb 27 2009 16:59:50][SmPolicyServer.cpp:1089][ERROR] Exception in JournalThread. Text: Policy store failed operation 'CleanServerCmds' for object type 'Policy store provider' Unexpected local error code -1063 while making database call.Error code -1063
Error code -1063 indicates that the policy server attempts to query a DataSource, in this case the policy server management thread was attempting to cleanup server commands in the policy store and didn't succeed.
For that ServerCommandTimeDelay can be used to give a chance to several policy server sharing a policy store to update their cache properly on a frequently updated policy store:
The value of the ServerCommandTimeDelay increases the range that a policy server will search for valid ServerCommands (e.g.Flush Cache); one this search is returned, the policy server must evaluate if the server command has previously been applied. The greater the value of ServerCommandTimeDelay, the more ServerCommands must be compared to the OldServerCommands list.
This is the overhead trade-off for a higher value.