As virtualization becomes more and more pervasive across the data center, many of my customers are now considering their vCenter Server as a tier 1 application. This means more focus is being places on maintaining the availability of vCenter Server. To quote Gene Kranz:
vCenter Server is central to the following aspects of a virtualized data center:
- provides DRS & DPM monitoring and host load management
- enables vMotion (central to both DRS and DPM)
- centralized management portal for all VMs and ESX server running in a cluster (ESX and VMs still run without vCenter, but management become much more cumbersome)
- feeding data from VMs and ESX to other IT management platforms
- hosts SRM plugin for VM business continuity between data centers
- provisions desktops for View (desktop virtualization)
There are a number of different strategies that can be taken to provide availability of the vCenter Server, these typically fall into one of two categories: a cold standby server or a warm standby server. Since the time needed to manually bring up a cold standby server for a large vSphere deployment can easily reach into the hours, most large organization tend toward a warm standby scenario and leverage some software automation to trigger the fail over. There are many options here that fall into the general categories of clustering or host replication. These tend to be complex and not always application specific.
To fill this gap and provide the monitoring and fail over needs of running vCenter Server as a teir 1 application, VMware recently released vCenter Server Heartbeat, which provides monitoring and automated fail over of both the vCenter Server and (optionally) the vCenter database.
Key aspects of Center Server Heartbeat:
- Monitors application (vCenter Server and optionally vCenter Database), network, and OS
- underlying technology licensed from NeverFail for vCenter Server and SQL Server awareness and fail over
- Supports VM or Physical deployments of vCenter Server
- Uses replication engine to replicate data and transactions to standby server
- fail over of vCenter and Database across wan or LAN
- Protects from Split Brain scenario if a network outage were to occur
- Fail over of IP address so all hosts/VMs continue to function with vCenter normally
- Easy to configure, auto cloning of vCenter Server VMs (if deployed virtually) to create stand by server
My recommended approach to providing Tier 1 availability of the vCenter server
- Ideally: run your vCenter server as a VM and utizliae vCenter Server Heartbeat to monitor and fail over vCenter. All accomplished with the minimal amount of configuration due to vCenter Server Heartbeat’s VM cloning capabilities.
- Minimally: run vCenter server as a VM and configure a HA pair for that VM. vCenter HA operates independantly of vCenter Server and will function even when the vCenter serer fails. Becuase it is designed to provide general HA for a wide variety of situations, it is not application aware like vCenter Server Heartbeat. Also, many architects don’t prefer this solution becuase the fail over is being provided by the tool that you are trying to protect. But, it is better than no fail over solution for vCenter Server.