Installation guide

Table 21-3. Condition and State Trigger Components (Continued)
Trigger Component Description
Warning The value that must be reached for the alarm to transition from a normal state to a
warning state, and to trigger the alarm.
Condition Length For condition triggers, after the warning condition is reached, the amount of time the
warning condition stays true in order for the warning to trigger.
State triggers do not have condition lengths. As soon as the state condition occurs, the
warning is triggered.
Alert The value that must be reached for the alarm to transition from the warning state to an
alert state and to trigger the alarm.
Condition Length For condition triggers, after the alert value is reached, the amount of time the alert
condition stays true in order for the alarm to trigger.
State triggers do not have condition lengths. As soon as the state condition occurs, the
alert is triggered.
For condition triggers to generate a warning or an alert, the value you set must be reached and for the specified
condition length. For example, you can configure a condition trigger to generate a warning and an alert under
the following conditions:
n
A virtual machine’s CPU usage must be above 75% for more than 10 minutes to generate a warning.
n
A virtual machine’s CPU usage must be above 95% for more than 5 minutes to generate a warning.
The 10 minute and 5 minute time conditions in this example help distinguish an erratic condition from a true
scenario. You set time requisites to ensure that the metric conditions are valid and not caused by incidental
spikes.
Triggered alarms reset when the triggering condition or state is no longer true. For example, if you have an
alarm defined to trigger a warning when host CPU is above 75%, the condition will reset to normal when the
value falls below the 75% and the warning alarm will no longer be triggered. The threshold condition is
dependent on any tolerance range you set for the threshold.
Virtual Machine Condition and State Triggers
VMware provides default triggers that you can use to define alarms on virtual machines when they undergo
certain conditions and states.
Table 21-4 lists the Condition and State triggers you can set on virtual machines.
Table 21-4. Virtual Machine Condition and State Alarm Triggers
Trigger Type Trigger Name Description
Condition CPU Ready Time (ms) The amount of time the virtual machine was ready during the collection
interval, but could not get scheduled to run on the physical CPU. CPU ready
time is dependent on the number of virtual machines on the host and their
CPU loads.
Condition CPU Usage (%) Amount of virtual CPU (MHz) used by the virtual machine. CPU limits are
ignored in the calculation. The calculation is:
VM CPU Usage (%) = VM CPU [MHz] / (# of vCPUs x clock rate of the physical
CPU [MHz]) x 100
Condition Disk Aborts Number of SCSI commands that were not completed on each physical disk
of the virtual machine.
Condition Disk Resets Number of SCSI-bus reset commands issued on each physical disk of the
virtual machine.
Condition Disk Usage (KBps) Sum of the data read and written across all disk instances on the virtual
machine.
vSphere Basic System Administration
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