Turn on Fault Tolerance option is disabled

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms:

• A virtual machine's Turn on Fault Tolerance option is greyed out
• A virtual machine's Turn on Fault Tolerance option is disabled
• You cannot turn on Fault Tolerance.

Environment

VMware ESXi 7.0.x

VMware ESXi 8.0.x

Resolution

For the Turn on Fault Tolerance option to be visible, these requirements must be met. If any of the following is not configured correctly, the option is not displayed. Ensure each of the following are properly configured:

1. Ensure VMware software compatibility. All versions of the VMware software used in a Fault Tolerance environment must be compatible. Ensure that the versions installed at your site are listed as compatible in the vSphere Compatibility Matrix.
    
2. On a hardware and guest operating system level, only certain processors and operating systems are supported. For more information on this support, see VMware Fault Tolerance
   Note: SMP (Multiprocessor) virtual machines are not supported with VMware Fault Tolerance at this time.
    
3. Hardware Virtualization (HV) must be enabled in the BIOS for each host in the cluster. The process for enabling HV differs in each BIOS. For this reason, contact your hardware vendor for instructions on enabling HV.
    
4. All ESXi hosts used by VMware Fault Tolerance must be members of a VMware High Availability (HA) cluster. VMware HA must be enabled for VMware Fault Tolerance to function. Instructions for enabling VMware HA can be found in the vSphere Availability
    
5. The ESXi hosts that run the primary and secondary Fault Tolerance nodes must be running the same build of ESXi. Additionally, patches have been released that contain improvements to the VMware Fault Tolerance features. For this reason, VMware strongly suggests updating to the most current version available.
    
6. There are several important considerations relative to storage for VMware Fault Tolerance. Ensure each of the following are configured for your environment to enable VMware Fault Tolerance:
   • The virtual machine must reside on shared storage. This is storage that is visible to all ESXi hosts in the cluster.
   • Storage must be FC SAN, iSCSI or NFS, but not local storage.
   • Virtual RDMs are supported, but Physical RDMs are not.
   • Virtual Disk files must be Thick Provisioned.
   • Virtual machines cannot have snapshots. If there are snapshots, these must be committed before proceeding.
      
7. Networking must be configured properly to ensure proper VMware Fault Tolerance functionality. Ensure each of the following is defined appropriately:
   • A separate VMkernel port group must be defined for Fault Tolerance logging. Instructions for creating this portgroup can be found in the Networking chapter of the ESXi Configuration Guide.
   • Fault Tolerance logging and VMotion portgroups must be defined and assigned a physical network card for uplink. This network card must be at least 1Gb, with a 10Gb card preferred.
   • Enable use of Jumbo Frames for the Fault Tolerance logging. For detailed steps, see the Advanced Networking section of the ESXi Configuration Guide.
   • VMware recommends enabling fully redundant NICs to ensure availability, though Fault Tolerance can function without it.

For more information about VMware Fault Tolerance, see VMware Fault Tolerance FAQ.