With nested ESX humming along happily I decided it was time to get serious about simulating a typical enterprise virtualization architecture.  My goal is to be able to test pretty much anything in the VMware product line and that means SRM which means multiple datacenters, but more importantly, multiple vCenters.  With nsted, this becomes super easy.  Here is how I decided to parcel out my resources:

A few things to keep in mind when setting up the hosts (this applies to all VMware designs):

• It’s a good best practice to isolate different types of management traffic. Even though this isn’t really relevant when all of these NICs are virtual and riding on one (or a few) physical host NICs, it’s also very easy with nested since it’s just software and it’s a good habit to get into.  Be sure to setup at least two vmkernel NICs for the vSwitch where the management port groups live.  Make sure that these vNICs are configured for fault tolerance and that at least two have “Management Traffic” checked.  This will remove any warnings about Management Network Fault Tolerance.  Done right, the final visual overview of the vswitch should look like this:

• When configuring an HA/DRS cluster, vCenter will look to find two shared datastores that can be used for heartbeat exchange.  This is less easy in a nested setup where you aren’t connecting hosts to a SAN or NAS.  The best solution here is really to introduce a NAS into the mix.  In my case I created both an iSCSI target and an NFS share and configured each host for access to both.  Within a few minutes vCenter will pick up on the fact that the cluster member hosts have two datastores each in common and will clear the warning.  Below you can see both the NFS and iSCSI datastore overviews.  Note that the iSCSI target also has the physical host configured since I use a single iSCSI target globally:

Ultimately my multi-vCenter, multi-virtual datacenter nested implementation will follow the architecture diagram presented below.  Note that the plan is to deploy vCD instances into both vCenter implementations: