Key Concepts in Capacity Analytics > Optimal VM Sizing > Right VM Size

Right VM Size

SHO identifies the undersized and oversized VMs in your data center. It then provides VM sizing recommendations that you can use to size the VMs appropriately so that the VMs are no longer underutilized or over utilized.

SHO uses the undersized VMs utilization threshold for the right sizing procedure.

SHO calculates the right VM size using the following procedure:

  1. SHO calculates the effective utilization threshold as follows:

    Effective Utilization Threshold = (Utilization Threshold for Undersized VMs) - (Headroom)

  2. SHO sets the new configured capacity ensuring that the new utilization threshold is equal to the effective utilization threshold percentage.

    Note: This procedure is used for both undersized and oversized VMs.

Based on the VM right sizing option selected on the Thresholds tab of the Configurations View page, SHO considers either the peak, average, or 95th percentile utilization data for the right sizing of VMs.

Consider the following example for calculating the right VM size:

  1. The utilization threshold for undersized VMs is defined as 80% and the headroom is set as 20%.

    The peak memory utilization during the analysis period is 3 GB.

  2. SHO calculates the effective utilization threshold as:

    Effective Utilization Threshold = (Utilization Threshold for Undersized VMs) - (Headroom) = 80-20 = 60%

  3. Hence, SHO calculates the ideal memory size as: (3/60)*100 = 5 GB.


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