Thanks marcdrinkwater and mittim12,
If max host memory it can use is 2 GB, the following second paragraph (from http://myvirtualcloud.net/?p=3234) says in other way, it says 3.5 GB of host memory will be utilized in this example. Can you please correct if my understanding is not correct?
For each VMDK digest created approximately 24MB of RAM will be consumed, in addition to the defined CBRC cache. As an example, if only one system disk is being hashed and the host cache is 50MB, than: 500MB + 24MB = Total of 524MB memory used.
Remember that it is possible to create digests for System and Persistent disks. In another example, if 64 VMs are in use there would be 64 Persistent Disks, plus 1 replica disk. In this case we would have 65 VMDK to be hashed. Assuming that host cache is using 2GB RAM (maximum size), than: 2048GB + (65 * 24MB) = Total of 3.5GB memory used.