Q&A: How Should I Calculate Swap Size on Virtualization Hosts?

virtualization
performance
memory
swap
ram
q-a

#1

Question

How Should I Calculate Swap Size on Virtualization Hosts?

Answer

First, calculate the estimated maximum overcommit ratio:

((sum of assigned memory of all virtual machines) / physical available memory)-1=overcommit ratio

Based on this calculate recommended swap size:

(0.5 * memory) + (overcommit ratio * memory) = recommended swap size

Example:

Host has physically 32GB of memory.
There are 10 virtual machines configured with each 4GB of memory assigned.

overcommit ratio=(10 * 4)/32-1=0.25
swap size=(0.5 * 32)+(0.25 * 32)=24GB

In this case, swap space of 24GB should be configured.


#2