VMware HA (High Availability) is a utility that the need for dedicated standby hardware and software in a virtualized environment. The utility is part of a virtualization suite called VMware Infrastructure 3.5. The term high availability refers to a system or component that is continuously operational for long periods.
Key features of VMware HA include:
- Proactive monitoring of all physical servers and virtual machines
- Automatic detection of server failure
- Rapid restart of virtual machines affected by server failure
- Optimal placement of virtual machines after server failure
- Scalable availability up to 32 nodes across multiple servers
If an ESXi server fails, the VMs hosted on it will go down or at least become unreachable. VMware HA responds by restarting the VMs on other hosts in the cluster that survived the failure. This assumes that protected VMs are hosted on shared storage that is accessible to other hosts in the cluster. VMware High Availability should be used to maintain uptime on important but non-mission-critical VMs. While HA cannot prevent VM failure, it will get VMs back up and running with very little disturbance to the virtual infrastructure.
VMware HA is great in restoring normal operation atomically in a very short time. The benefits are without a doubt very valuable for the organization. Consider the value of HA for host failures that occur in the early hours of the morning, when IT is not immediately available to resolve the problem.