To speed the failover process, the idsync resync operation is run periodically on the failover installation to keep the object cache database in the Active Directory Connector up-to-date. If the object cache is not kept up-to-date, then the Active Directory Connector will detect and propagate many changes that were already synchronized by the primary installation. Not keeping the object cache database up-to-date will significantly increase the load, and will place a heavier load on Directory Server during the failover scenario.
The same resync-recent.pl script is used in this scenario except that it is run from the failover installation Core machine, config-eu.gt.com. The cron command is used to run the script daily with the following arguments. The -u option is specified to only update the Active Directory Connector's object cache.
resync-recent.pl ad3-eu.gt.com usnCreated -u -b -w - -q - < /var/opt/SUNWisw/passwords
The more often this script is run in the failover environment, the more likely changes will be lost during the failover process. idsync resync -u should not be run after the primary installation fails. If the command is run often (for example, every hour), then it is likely that it will be run while the primary installation has failed, but the failure has not yet been detected. As this script keeps track of a three-day history of the highestCommittedUSN values, it could be updated to search for entries that were modified in the last three days but not modified in the last day. As long as the primary installation failure is detected within one day and the cron job of this script was stopped, no Active Directory changes are lost.