By default, vCenter Operations uses dynamic thresholding for attributes. This is also what I recommend as there are many limitations with static threshold, especially in dynamic environment like vSphere 5. A hard threshold is static. A hard threshold changes _only_ when you change it.
You can set multiple static thresholds, each with a different criticality level, for the _same_ attribute.
You can also define the criticality level that a metric must violate for it to be considered a KPI breach. Hard thresholds that are not set as KPIs generate notification alerts if they are violated.
In the rare event you need to set a hard thresholds, the steps are below. In this example, I want to set threshold for Ready Time.
All metrics are grouped together into packages. So choose Attribute Packages from the menu, as shown below.
It will pop up the dialog box below.
I’ve filtered the list by choosing Virtual Machine.
After I clicked the above icon to edit it, it pops up the dialog box below.
From there, I chose CPU, then selected Ready%. It brings up the details.
I also clicked the Advanced Configuration to expand the section. It is hidden by default.
From the above, I’ve ticked that valuation of upper limit and lower limit are considered KPI.
vCenter Operations Manager multiplies the wait cycle value by the collection interval to calculate the number of minutes that a threshold must be out of bounds before generating an anomaly. So in my case, the warning Critical Level has to happen for 10 minutes (5 minutes interval x 2 wait cycle) before it gets triggered. In the same manner, the info Critical Level only gets triggered if it is sustained in 15 minutes.
vCenter Operations Manager multiplies the cancel cycle value by the collection interval to calculate the number of minutes the metric must be in bounds before canceling an anomaly. So in my case, it only waits for 5 minutes (1 internal) to clear it. If you want to be more certain that it is completely “gone”, you might want to wait for a few more samples (cycles).
Hope that helps.