VVR uses a heartbeat mechanism to detect communication failures between the Primary and the Secondary hosts. The RLINKs connect after the heartbeats are exchanged between the Primary and the Secondary. The RLINK remains connected while the heartbeats continue to be acknowledged by the remote host. The maximum interval during which heartbeats can remain unacknowledged is known as the heartbeat timeout value. If the heartbeat is not acknowledged within the specified timeout value, VVR disconnects the RLINK.

The vol_nm_hb_timeout tunable allows the heartbeat timeout value to be specified. The default is 10 seconds. For a high latency network, increasing the default value of the vol_nm_hb_timeout tunable prevents the RLINKs from experiencing false disconnects. The maximum value that it can be set it to is 60 seconds..

The following command can be used to display its current value:

#  vxtune vol_nm_hb_timeout
Tunable                                        Current Value                Default Value Reboot Clusterwide
-------------------------------                -------------                ------------- ------ -----------
vol_nm_hb_timeout                                         10                        10    N        N

To change its value the following command can be used:

#  vxtune vol_nm_hb_timeout

For example:

#  vxtune vol_nm_hb_timeout 60
Tunable                                        Current Value                Default Value Reboot Clusterwide
-------------------------------                -------------                ------------- ------ -----------
vol_nm_hb_timeout                                         60                        10    N        N