Pod like Architecture for vCloud Director
It is strongly recommended by VMware to create a pod based architecture for any cloud based architecture. Pod helps you scale your design horizontally without impacting any core functionality of the architecture. Two major components forms the part of POD. On left hand side of the image below there is management pod and on right hand side there is resource pod. Management pod consists of
vCloud Director Cell
vCNS Manager (vShield Manager)
vSphere Update Manager
Database for vCenter, vCloud Director, VUM database, Orchestrator, vCenter Charge back
vCenter Chargeback manager
vCloud Connector (for Hybrid solution)
vCAC for automation manager
On the right hand side we have resource Pod. Resource Pod is the one which provides resources to vCloud director. These resources are generally formed in the form of cluster. Cluster can provide you storage, vMotion boundary. In above figure resource pod is further divided into three clusters i.e. GOLD, SILVER and BRONZE. These clusters depicts the various tiers available. Though I have not broadly defined how these tiers differ from each other. These tiers forms the basis of provider virtual datacenter (vDC). So each tier actually translates into Provider vDC as far as vCloud director is concerned. i.e. vCloud director has now three different tiers of services. As your customer grows you can grow scale these tiers horizontally. Scaling of these tier is limited by underline vSphere limitations. e.g. maximum number of nodes per cluster you can have is 32. As you reach this number you would need to add another cluster.
Without management pod in place DR of resource workload becomes extremly complicated.
Management Pod manages resource pod i.e. vCenter which manages these cluster will be in management POD and similarly vCloud director cell will be in the management tier.