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 . Reasons can be: a) network  b) OS issues c) DB2 problems.

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.

Therefore ,

a)  For data consistency , go for a non-zero value

b)  For data availability , consider a zero value

Author: Jack Vamvas