CPU calculations

The following are the calculation-related assumptions:

• 200 virtual machines
• No CPU oversubscribing

Processor over subscription is defined as the total number of CPUs that are assigned to all the powered-on virtual machines multiplied by the hardware CPU core. If this number is greater than the GHz purchased, the environment is oversubscribed.

• GHz per physical core = 2.6 GHz
• Physical core hyper-threading support = use factor 2
• GHz per VM (AVG compute units) = 2 GHz
• GHz per VM (MAX compute units) = 16 GHz
• Intel Xeon E5-2648L v2 core CPU = 10
• CPU sockets per server = 2

The formula for calculating the total number of CPU cores is as follows:

(number of VMs x number of GHz per VM) / number of GHz per core

(200 * 2) / 2.6 = 153.846

We have 153 CPU cores for 200 VMs.

The formula for calculating the number of core CPU sockets is as follows:

Total number of sockets / number of sockets per server

153 / 10 = 15.3

We will need 15 sockets

The formula for calculating the number of socket servers is as follows:

Total number of sockets / Number of sockets per server

15 / 2 = 7.5

You will need around seven to eight dual socket servers.

The number of virtual machines per server with eight dual socket servers is calculated as follows:

We can deploy 25 virtual machines per server

200 / 8 = 25

Number of virtual machines / number of servers