Command Center monitors the health of a device by polling the performance counters supported by the device. Command Center supports more than 300 counters for NetScaler (including NetScaler VPX and NetScaler Gateway) devices and more than 20 counters for CloudBridge devices. There are two types of counters: scalar and vector. The scalar counters (for example, TCP and UDP) are device-level, and they are enabled for polling by default.
The vector counters, which are identified by plus (+) signs following the counter names, are entity-level counters that display statistics for entities, such as interfaces, vservers, services, and service groups. You have to enable the vector counters explicitly. They are not enabled for polling by default because they may impact the Command Center server performance if there is a large number of entities configured on the devices. Enable polling on vector counters only when you need to monitor them.
If you run reports on counters that are not enabled for polling, the following error appears: "The selected counter is not enabled for polling. Enable the counter using the Polled Counters option and try again." If you run a report on a counter that the device does not support, the following error appears: "The managed device(s) may not support the selected counter(s). Modify your selection of the counter(s) and try again."
The default polling interval value set by Command Center is 300 seconds. If you do not change the default polling interval, Command Center polls data from the devices every 5 minutes (300 seconds) and stores this data in its database. You can view the last polled data using quick reports, custom reports, or trend reports. The different types of reports are explained in the following sections. Note that if you have a higher number of counters enabled, it is advisable to set a higher polling interval to prevent performance overload on the network. However, if you want more detail, you may enable only a few counters and decrease the polling interval value. The minimum polling interval value Command Center supports is 30 seconds.