Edit cluster health monitor settings

This task allows you to modify cluster health monitor settings to control how cluster nodes monitor system health and automatically rejoin the cluster after failures.

The Cluster Health Monitor Settings section of the Cluster page displays the settings for monitoring cluster node health. You can monitor any port-channel ID, any single physical interface ID, and the Snort and disk-full processes. Health monitoring is not performed on VLAN subinterfaces or virtual interfaces such as VNIs or BVIs. You cannot configure monitoring for the cluster control link. It is always monitored.

When a topology change occurs (such as adding or removing a data interface, enabling or disabling an interface on the node or the switch, or adding an additional switch to form a VSS or vPC or VNet) you should disable the system health check feature. Also, disable interface monitoring for any interfaces that are disabled. When the topology change is complete, and the configuration change is synced to all nodes, you can re-enable the system health check feature and monitored interfaces.

Procedure

Step 1	Choose Devices > Device Management.
Step 2	Next to the cluster you want to modify, click Edit ().
Step 3	Click Cluster.
Step 4	In the Cluster Health Monitor Settings section, click Edit ().
Step 5	Disable the system health check by clicking the Health Check slider. Disable the system health check When any topology changes occur (such as adding or removing a data interface, enabling or disabling an interface on the node or the switch, or adding an additional switch to form a VSS or vPC or VNet) you should disable the system health check feature and also disable interface monitoring for the disabled interfaces. When the topology change is complete, and the configuration change is synced to all nodes, you can re-enable the system health check feature and monitored interfaces.
Step 6	Configure the hold time and interface debounce time. Hold Time—Set the hold time to determine the amount of time between node heartbeat status messages, between 0.3 and 45 seconds. The default is 3 seconds. Interface Debounce Time—Set the debounce time between 300 and 9000 ms. The default is 500 ms. Lower values allow for faster detection of interface failures. Note that configuring a lower debounce time increases the chances of false-positives. When an interface status update occurs, the node waits the specified number of milliseconds before marking the interface as failed and removing the node from the cluster. If an EtherChannel transitions from a down state to an up state, such as after the switch reloads or enables an EtherChannel, a longer debounce time can prevent the interface from appearing failed on a cluster node if another cluster node bundles the ports more quickly.
Step 7	Customize the auto-rejoin cluster settings after a health check failure. Configure Auto-Rejoin settings Set values for the Cluster Interface, Data Interface, and System (internal failures include: application sync timeout; inconsistent application statuses; and so on): Attempts—Sets the number of rejoin attempts, between -1 and 65535. 0 disables auto-rejoining. The default for the Cluster Interface is -1 (unlimited). The default for the Data Interface and System is 3. Interval Between Attempts—Defines the interval duration in minutes between rejoin attempts, between 2 and 60. The default value is 5 minutes. The maximum total time that the node attempts to rejoin the cluster is limited to 14400 minutes (10 days) from the time of last failure. Interval Variation—Defines if the interval duration increases. Set the value between 1 and 3: 1 (no change); 2 (2 x the previous duration), or 3 (3 x the previous duration). For example, if you set the interval duration to 5 minutes, and set the variation to 2, then the first attempt is after 5 minutes; the 2nd attempt is 10 minutes (2 x 5); the 3rd attempt 20 minutes (2 x 10), and so on. The default value is 1 for the Cluster Interface and 2 for the Data Interface and System.
Step 8	Configure monitored interfaces by moving interfaces in the Monitored Interfaces or Unmonitored Interfaces window. You can also check or uncheck Enable Service Application Monitoring to enable or disable monitoring of the Snort and disk-full processes. Configure monitored interfaces The interface health check monitors for link failures. If all physical ports for a given logical interface fail on a particular node, but there are active ports under the same logical interface on other nodes, then the node is removed from the cluster. The time required to remove a member from the cluster depends on the type of interface and whether the node is established or is joining the cluster. By default, health check is enabled for all interfaces and the Snort and disk-full processes. You might want to disable health monitoring of non-essential interfaces. When any topology changes occur (such as adding or removing a data interface, enabling or disabling an interface on the node or the switch, or adding an additional switch to form a VSS or vPC or VNet) you should disable the system health check feature and also disable interface monitoring for the disabled interfaces. When the topology change is complete, and the configuration change is synced to all nodes, you can re-enable the system health check feature and monitored interfaces.
Step 9	Click Save. Deploy configuration changes.