Minimize Downtime from Server and OS Failures

VMware vSphere® High Availability (HA) delivers the availability required by most applications running in virtual machines, independent of the operating system and application running in it. HA provides uniform, cost-effective failover protection against hardware and operating system outages within your virtualized IT environment. HA can:

  • Monitor VMware vSphere® hosts and virtual machines to detect hardware and guest operating system failures.
  • Restart virtual machines on other vSphere hosts in the cluster without manual intervention when a server outage is detected.
  • Reduce application downtime by automatically restarting virtual machines upon detection of an operating system failure.

Extend and Enhance Protection Across Your Infrastructure

Availability solutions tied to operating systems or applications require complex setup and configuration. In contrast, configure HA with a single click from within the vSphere client interface. With simple configuration and minimal resource requirements, HA lets you:

  • Provide uniform, automated protection for all applications without modifications to the application or guest operating system.
  • Establish a consistent first line of defense for your entire IT infrastructure.
  • Protect applications that have no other failover options, which might otherwise be left unprotected.

Technical Details

HA provides the foundation for a highly available environment by monitoring virtual machines and the hosts upon which they run. HA is a mature solution that provides scalability, reliability and usability:


  • Master-slave node relationship - This new relationship model between nodes in a cluster replaces primary and secondary nodes. Availability actions are coordinated by a single master node, which communicates all activities and states to VMware® vCenter Server™. This eliminates much of the planning required to design a highly available environment—administrators no longer need to worry about which hosts are primary nodes and where they are located. This is especially significant when deploying HA on blade chassis and in stretched cluster environments.
  • Support for IPv6 networking - Enables IT departments in need of a larger “address” space to fully leverage their network infrastructure.
  • Simple deployment mechanism - Fast and easy completion of routine tasks such as deploying vSphere HA agent and configuring HA functionality.


When an outage occurs, the last thing administrators need is to worry about whether their high availability solution will work. Guided by real-world customer feedback, VMware has added capabilities to maximize your confidence in HA:

  • No external component dependencies - HA has no dependency upon DNS resolution. This reduces the odds that an external component outage will impact HA operations.
  • Multiple communication paths - HA nodes within a cluster can communicate through the storage subsystem as well as over the management network. Multiple communication paths increase redundancy and enable better assessment of the health of a vSphere host and its virtual machines.
  • VM-VM anti-affinity rules - HA has been enhanced to respect VM-VM anti-affinity rules defined in VMware vSphere® Distributed Resource Scheduler™, eliminating the need for VMware vSphere® vMotion® migrations after failover.


HA’s enhanced interface lets users quickly identify the role and state of each node in a cluster. Error condition messages are also easier to understand and act upon. In the rare case that an issue does occur with HA, only one log file needs to be reviewed, speeding time to resolution.