Scrubbing parameters for replicas
When a command makes a change to a replica, an entry is recorded
in the replica’s operation log. Also, when you export an update packet, an
export_sync record is created for each target replica. These records are used
by the recoverpacket command to reset a replica’s epoch number matrix.
You can scrub oplog entries and export_sync records to reclaim disk space and database records, but you must keep them long enough to ensure that you can recover from replica failures and packet losses.