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vCSHB creates a clone of both the vCenter Server and the SQL server, and then keeps both the primary and secondary vCenter Servers in sync through continuous asynchronous replication. Administrators can use vCSHB in a virtual configuration, physical configuration or a hybrid model.
vCSHB can be configured to work solely on a private LAN or stretched across two sites in "DR Mode;" the latter allows administrators to use different IP ranges, and have a user account send DNS updates in the event of failover, redirecting users and services to a functioning vCenter Server.
The primary and secondary vCenter Servers each have two NICs: The first handles the primary incoming traffic (Principal Public Network) from the vSphere Client, and the second handles replication and the "heartbeat" signal, referred to as the "VMware Channel." Administrators can also configure vCSHB to monitor and trigger remediation tasks associated with degraded performance issues.
With vCSHB, in contrast to traditional high availability (HA), administrators do not have to manage shared volumes or quorums. All activity takes place inside the guest operating system, helping administrators avoid conflicts with vMotion, VMware HA or Distributed Resource Scheduler that can result from traditional clustering.
See also: Heartbeat