Setting HADR_PEER_WINDOW at zero , only blocks primary transactions for the time specified in HADR_TIMEOUT. If the HADR_PEER_WINDOW is set to greater than zero, then the Primary database waits until the connection is restored or the HADR_PEER_WINDOW period finishes. Connections between the Primary and Standby databases are temporarily broken . Possible reasons can be: a) network b) OS issues c) DB2 problems. How to report a DB2 performance problem Leaving the HADR_PEER_WINDOW at zero , is beneficial to maintain availability. At zero, soon as the connection between Primary and Standby closes , the Primary is no longer in Peer state.... Read more →