One ESX Host ? - All your eggs in one basket

If you have (lets say) 10 Virtual Machines running on this ESX Host, all of a sudden this PC becomes very important (10 times more so than when you had 10 separate PC’s) !

If you need to add memory, or perform maintenance which requires the PC (ESX Host) to be turned off, you will effectively have to shut down all 10 Virtual machines running on it, which may effect your production and so be impractical.

Two or more ESX Hosts – Fault Tolerant & Load Balancing

Luckily help is at hand. Your single ESX host essentially defines your pool of IT resources (Known as a VMware Resource Pool). You can add an additional ESX Host into this pool, and so know you have 2 ESX Hosts, sharing the workload of the 10 virtual machines.

This has the immediate potential benefits:-

• Configured correctly, these two machines are lock-stepped together, which means you can turn one off, with no effect on the Virtual Machines running on them ! Ideal if you need to perform maintenance on one of them. Or you have a power failure to one of them.
• If load balancing is set up, then the 2 ESX Hosts can share the workload and negotiate who is going to do what. Therefore if you have a virtual machine that has instances of high CPU usages, then the system can allocate extra resources from the Pool to this VM, and migrate other tasks to the other host.