cluster.mem[name,usage]

[Spuun1]

This doesn't return the memory usage of a cluster. It results the amount of memory used by cluster services etc. (effective memory usage) . Effective memory is the amount of memory available for virtual machines.

Effective Memory = Aggregate host machine memory - (VMkernel memory + Service Console memory + other service memory)

Cluster memory usage should be calculated like this:

Cluster: memory usage = memory consumed + memory overhead ÷ effectivemem

as it's explained in https://www.vmware.com/support/developer/vc-sdk/visdk400pubs/ReferenceGuide/memory_counters.html

Could this be retrieved for cluster from root resource pool?

https://www.vmware.com/support/developer/vc-sdk/visdk25pubs/ReferenceGuide/vim.ResourcePool.html

And for last but not least thanks to dav for this great tool!