Cluster Capacity + Templates

Discussion created by tomburkevmt on May 25, 2016
Latest reply on Feb 3, 2020 by chad.parris

So, first off what is the Cluster Capacity dashboard?


This dashboard answers the question, “How many VMs can I safely add to a given cluster?” The dashboard shows how much extra capacity your clusters have as VMheadroom. It can show headroom on the physical hosts or the datastores in a cluster. To calculate cluster capacity and headroom, Operations Manager runs planning scenarios that take into account all the conditions in your current environment.

The plan uses the Economic Scheduling Engine to identify the optimal workload distribution for each cluster. This can include moving your current VMs to other hosts within the given cluster, if such moves would result in a more desirable workload distribution. The result of the plan is a calculation of how many more VMs the cluster can support.


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To calculate VM headroom, the plan must assume each additional VM has been allocated a certain capacity for its resources. To accomplish this, the plan uses a VM template as a profile for the VMs that fill the cluster’s headroom. For this reason, the count of VMs given for the headroom is an approximation based on that VM template.


Differences between Templates


AVG Utilization - Operations Manager averages all the values in each polling sample. It generates the average template daily.

MAX Utilization - Operations Manager uses the greatest value in each polling sample. This gives the highest percentage utilization for the selected VM (or group of VMs), calculated over the selected time period. For a maximum value, Operations Manager uses the highest observed active memory value in the data sample.

Discovered Templates - Operations Manager creates a number of VM Templates automatically as it discovers source VM data on the target hypervisors. These templates represent typical VMs that can be deployed from the given hypervisor manager

Authored Templates - You can create your own VM templates to represent typical workload, or to represent hypothetical workload that you might want to try out in a planning scenario.


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Run More than 10 Clusters per Night


By default, Operations Manager runs Cluster Capacity plans on 10 clusters a night. To specify a different number of plans to run, select the Global scope and change the value of the numClusters setting.


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