vSphere 6.0 blog – Fault Tolerance


This is the second part of the new vSphere 6.0 improvements and or new features blog series. The first part covered the vMotion improvements and can be found here. VMware vSphere 6.0 documentation page including release notes, installation documents, upgrade documents, component documentation and so on can be found here.

This part of the blog series will cover the vSphere Fault Tolerance which is a feature that provides you zero downtime for a virtual machine (VM) during an ESXi host failure (hardware and/or software). The previous FT feature used VMware vLockstep technology which you can read more about here. The new FT version uses Fast Checkpointing that is very fast and permit continuous copying/checkpointing of the VM.

For a few years now the vSphere Fault Tolerance (FT) feature has been limited to protect VMs with one vCPU. I have seen technical previews of the feature supporting more than 1 vCPU a few times over the years while visiting VMworld events.

Now it is finally here and FT now supports 4 vCPUs. This includes the new setup of the FT protected VM which consists of one primary VM and one identical running copy of the same called secondary VM:

  • one configuration, .vmx, file per VM (primary and secondary). This is same as previous version
  • separate VMDK (disk and disk configuration files). This is NEW in this release of FT.
  • Allowed to be on different datastores. This is NEW in this release of FT.
  • Does not require Eager Zeroed Disk, can use any disk format. This is NEW in this release of FT.
  • Hot configure FT. This is NEW in this release of FT.

This means you can protect a complete other types of workloads and one that pops up in my mind immediately is the vCenter Server. The vCenter Server is a critical component for traditional vSphere environments from a management perspective and from both a management and functionality perspective when you add services such as VMware Horizon View, vCloud Director and vRealize Automation.

At present time, 2015-02-09, before vSphere 6.0 GA VMware says the protecting vCenter Server using FT will be supported in some cases. I’ll update the blog post when i get more information.

Anyway, it’s great being able to add this new level of availability for the management component with a vSphere out of the box (OOB) feature.

Because of the Fast Checkpointing technology the new FT feature is more resource intensive and requires a 10 Gbps connection since data will be copied between the ESXi hosts running the primary and secondary VM. A maximum of 4 VMs or 8 vCPUs can be protected per ESXi host, whichever limit is reached first.

The third blog post in the series covers Multi-Site Content Library and can be found here.

vSphere 6.0 configuration maximums can be found here.

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