With a vSphere Client, you can easily check the memory information of a host, either ESX or ESXi. To get that, you click on a host from the inventory tree, and then configuration tab. From the left side Hardware section of the configuration page, you click Memory and see a pane displaying the memory info as follows:
Note that if you have chosen a ESXi host, you won’t see the Service Console part because there is no console OS any more in ESXi. BTW, VMware wants you to migrate from ESX to ESXi and here is a link with helps.
This seemingly easy information is actually not easy to get. At first glance, it should be in the config property of HostSystem (managed object representing an ESX or ESXi). The config property has a sub property called systemResources, typed as HostSystemResourceInfo. But you will get null for the systemResources property most, if not all, of the time, as reported in VI Java API forum.
Interestingly enough, HostSystem has a systemResources property in peer to the config property as well. Luckily, it’s not null so you can dig down for something. Still, with 3 sub properties of complex types included, how to get the memory from the data object?
Here are the steps to collect and calculate the numbers: