If you use an
external system to perform health checks on the services and do not want the
NetScaler appliance to monitor the health of a service, you can set the
no-monitor option for the service. If you do so, the appliance does not send
probes to check the health of the service but shows the service as UP. Even if
the service goes DOWN, the appliance continues to send traffic from the client
to the service as specified by the load balancing method.
The monitor can be
in the ENABLED or DISABLED state when you set the no-monitor option, and when
you remove the no-monitor option, the earlier state of the monitor is resumed.
You can set the
no-monitor option for a service when creating the service. You can also set the
no-monitor option on an existing service.
The following are
the consequences of setting the no-monitor option:
- If a service for which you
enabled the no-monitor option goes down, the NetScaler continues to show the
service as UP and continues to forward traffic to the service. A persistent
connection to the service can worsen the situation. In that case, or if many
services shown as UP are actually DOWN, the system may fail. To avoid such a
situation, when the external mechanism that monitors the services reports that
a service that is DOWN, remove the service from the NetScaler configuration.
- If you configure the
no-monitor option on a service, you cannot configure load balancing in the
Direct Server Return (DSR) mode. For an existing service, if you set the
no-monitor option, you cannot configure the DSR mode for the service.