You have 3 type of swap files – 1. Host swap file (4GB) 2. VM swap file (Size of memory that you allocated to the VM – Space consideration when plan your design) 3. Guest OS swap file.
VM’s heavily rely on CPU cache – Get CPU’s with high L1/2/3 cache.
You could purchase solid state disks for the partitions where your host will be installed and store the VM’s swap files on there – This will improve performance.
If you don’t need to allocate additional vCPU to a VM then DONT – It will use extra memory overhead to run the VM’s (Rather assign an extra core if needed unless your app is configured to run with multi PROC).
Optimize VM’s according to NUMA – Don’t allocate more RAM to the VM than what is on the physical RAM section per CPU.
Plan 60% of resources for usage and 40% for maintenance and future growth.
Make sure you have enough resources on all hosts that are part of your HA or fault tolerance cluster to accommodate for VM’s that might be moved to host in case of another host failure.
Rather scale out than up for HA.
Don’t put your management and IP storage on the same network.
For HA implement redundancy heartbeat networks and redundant isolation addresses.
If you are planning to enable fault tolerance on VM’s then only assign 1 vCPU to the VM. FT is not supported on more (This is on vSphere 5.1 and earlier).