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Avoiding downtime with VMware Fault Tolerance and High Availability

VMware Fault Tolerance and High Availability are both related to uptime, but they have different features and take alternative approaches when a failure occurs. This guide explains how these functions operate in the virtualized data center.


VMware's Fault Tolerance (FT) and High Availability (HA) are both focused on uptime and keeping virtual machines running. Once a company determines its uptime and data recovery needs, it can decide whether High Availability or Fault Tolerance is the better choice.

While Fault Tolerance is a high availability feature that can be used in a VMware HA cluster, there are meaningful differences between the two. Each requires a setup with different available resources and both have a different effect on virtual machines.

The resources presented in this guide to VMware FT and HA will help you understand your options with some real-world use cases to compare to your IT infrastructure and needs.

1How uptime features compare-

The differences

The key difference between VMware's High Availability and Fault Tolerance offerings is the interruption to virtual machines in the event of a host failure. Fault Tolerance eliminates downtime -- even when hardware founders -- by keeping a copy of a critical virtual machine (VM) on another host. For VMs protected by High Availability, if the host running the VM fails, then the VM will get restarted on another server; if the VM fails because of an operating system crash, HA will restart the VM on the same host.


How Fault Tolerance works

In today's fast paced world, some businesses can't afford to have a workload interruption. Fault Tolerance, a feature in vSphere, ensures VMs will continue to function if a server goes under. Continue Reading


High Availability best practices and guidelines

Many people can confuse VMware High Availability with Fault Tolerance but HA only deals with restarting those virtual machines on other hosts that have the resources to support the VM Continue Reading


High Availability vs. Fault Tolerance

Choosing between VMware's High Availability and Fault Tolerance can be difficult but this breakdown on various scenarios can assist with the decision process. Continue Reading


Requirements for vSphere Fault Tolerance

An administrator who wants to implement Fault Tolerance needs to check several key areas to make sure a VM performs properly to ensure a server outage doesn't slow the business down. Continue Reading


A proper High Availability setup

When an ESXi host fails, High Availability brings virtual machines back to life, but only a proper setup will keep critical applications running at the required performance level. Continue Reading

2What's needed to run FT and HA-


It's important to differentiate how High Availability and Fault Tolerance operate. If you can't afford to have interruption, Fault Tolerance instantly gets to work after a host failure. HA can get virtual machines back up and running with very little disturbance.


Options for VMware High Availability

VMware High Availability comes from software, rather than hardware, features. This tip helps refine the settings that align with your environment's requirements. Continue Reading


What vSphere 5 brought to HA

When VMware released vSphere 5 a couple years ago, High Availability got an overhaul, including a new election process that helps determine what to do if a cluster node fails. Continue Reading


Requirements for Fault Tolerance and FT logging

It's crucial to know the Fault Tolerance requirements to ensure your customer's environment is safe in the instance of a host failure. Continue Reading


Server Heartbeat's death could mean more HA options soon

Without the option to purchase vCenter Server Heartbeat, administrators seeking high availability for vCenter Server have to weigh their options, which may include new choices down the road. Continue Reading


Multi-vCPU Fault Tolerance

At VMworld 2014, VMware released one of the biggest upgrades to Fault Tolerance when it announced multi-vCPU Fault Tolerance. Continue Reading

3How they work-

Using High Availability and Fault Tolerance

Now that you know what Fault Tolerance and High Availability are, it's time to focus on them in action. These real-world scenarios for implementation will help you to better understand how and why to use either tool.


Pairing VMware HA with DRS

Ensure you're taking full advantage of VMware HA and DRS by creating and documenting rules and policies. Together the pair can help improve virtual server performance and uptime. Continue Reading


Don't ditch DR for HA just yet

While there are high-availability features that make it seem like you can ditch disaster recovery, there is reason to rely on more than just HA clustering. Continue Reading


Building a KVM high availability cluster

High availability is more than just for VMware environments. Most Linux distributions include everything you need to build a KVM high availability cluster to protect your environment. Continue Reading


Scaling out to save money on a high-availability architecture

Traditional high-availability architectures rely on expensive shared storage and premium hypervisor features, but sometimes you can save money by scaling out instead of up. Continue Reading


When to enable Fault Tolerance

While it's easy to enable VMware Fault Tolerance, there is no need to use it on every virtual machine. Continue Reading

4Related VMware FT and HA terms-


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