VMware vSphere ^TM

VMware vSphere High Availability (HA) provides easy-to-use, cost effective high availability for applications running in virtual machines. In the event of physical server failure, affected virtual machines are automatically restarted on other production servers with spare capacity. In the case of operating system failure, vSphere HA restarts the affected virtual machine on the same physical server.

vSphere HA allows IT organizations to:

• Minimize downtime from server and operating system failure
• Increase protection across your infrastructure

vSphere HA delivers the availability needed by many 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 failures within your virtualized IT environment.

• Monitors virtual machines to detect operating system and hardware failures
• Restarts virtual machines on other physical servers in the resource pool without manual intervention when server failure is detected
• Protects applications from operating system failures by automatically restarting virtual machines when an operating system failure is detected

vSphere HA can be configured with a single click from within the vSphere Client interface to provide failover protection without requiring the complex setup and configuration of solutions tied to operating systems or applications. Because HA is simple to configure and requires minimal resources to provide protection, you can:

• Provide uniform protection of all of your applications from server and operating system failures, regardless of the server hardware or operating system used by the virtual machine
• Establish a consistent first line of defense for your entire IT infrastructure
• Protect applications with no other failover options and make high availability possible for software applications that might otherwise be left unprotected

HA can be purchased as a component of all VMware vSphere editions and Kits

The most widely used feature for availability in a virtualized environment is vSphere HA. vSphere HA provides the foundation for a highly available environment by monitoring the virtual machines and the hosts upon which they run.

In vSphere 5.0, the vSphere HA feature was completely rewritten by VMware to increase scalability, reliability, and usability. Each of these factors, and the enhancements incorporated to support them, are described below.

With the increased usage of VMware products in today’s modern datacenter comes a need to provide a scalable solution for high availability. The redesign of vSphere HA provides this foundation.

One of the biggest changes with vSphere HA is that the concept of primary and secondary nodes has been completely removed. The new model incorporates a master-slave relationship between the nodes in a cluster, where one node is elected to be a master and the rest are slaves. The master node coordinates all availability actions with the other nodes and is responsible for communicating that state to the VMware vCenter Server. This model eliminates a significant amount of planning in the architecture design of a highly available environment. No longer must administrators worry about what hosts are their primary nodes and where they are located. This is especially significant when implementing vSphere HA on blade chassis and in stretched cluster environments.

The support for IPv6 networking in vSphere HA enables IT departments in need of a larger addresses space to fully leverage their network infrastructure.

vSphere HA now also includes an enhanced deployment mechanism. This enhancement allows administrators to complete tasks in a fraction of the time required previously, such as with deployment of the vSphere HA agent, vSphere HA configure, unconfigure, reconfigure, and so on.

When a disaster event occurs, the last thing that an administrator wants to worry about is if the solution deployed will work properly. By analysis of the most common support calls made by customers about vSphere HA, VMware added features to ensure continued confidence in vSphere HA.

One enhancement was the elimination of dependencies on any external component by vSphere HA. Specifically, vSphere HA no longer has any type of dependency upon DNS resolution by each host in the cluster. Eliminating this reduces the odds that an outage of an external component will have an effect on the operation of vSphere HA.

Another enhancement is the ability to enable communication between the nodes within a cluster through the storage subsystem. Now vSphere HA will utilize multiple paths of communication, through the network and storage. Not only does this allow for a greater level of redundancy, but it also enables better identification of the health of a node and the virtual machines running on it.

Although most of the enhancements made to vSphere HA are not visible to the end user, there was a focus on improving the usability.

The user interface has been enhanced to allow for users to quickly identify the role a node in the cluster plays, as well as its state. Messages reporting error conditions have also been made easier to understand and act upon. When problems do occur, there is just one log file that must be reviewed, greatly decreasing the time to resolution.