The other day I had a client request assistance with determining why mail file data was not replicating between cluster members. We started by reviewing the usual suspects – ACL enforcement, replication disabled, and log file data. In the end we discovered the problem was due to the deletion stub purge interval being a 0 value and PIRC being enabled.
Purge Interval Replication Control, (PIRC)
Domino 8.5.3 introduced a new replication control method called Purge Interval Replication Control, PIRC. Overall, PIRC prevents older documents from being replicated, commonly called “ghost” documents. For example, a server is offline for a long period of time and when it is restarted the next replication cycle results in a a number of deleted documents returning. This causes end user confusion and time has to be spent deleting unwanted documents again. PIRC stops this from happening.
PIRC uses an algorithm to calculate the replication cut off date, using the value in the replication settings Remove documents not modified in the last (days) field. This number is used to purge deletion stubs. At some point, most Domino administrators have set this value to 0 to remove the deletion stubs from a replica in order to prevent accidental deletions from replicating to other servers and allowing replication to restore those documents. With the purge interval set to a 0 value the PIRC time date is the current time, which means virtually no documents will replicate.
To allow the documents to start replicating between the replicas the purge interval simply needs to be set to a value higher than 0 on all replicas. However, take caution with how the database may look after the next replication cycle. For example, in a case where two replicas have not synchronized in a year, a number of previously deleted documents will return and documents not available in the one replica being used will suddenly appear – both causing the end user to wonder what just happened. Ensure good backups of the databases exist and communicate what will happen to ensure a successful mitigation process.