VMware FT

Version 8

    FT Information


    Meet the Engineer Series: VMware Fault Tolerance

    A Summary of FT Related Documents

    http://www.vmware.com/files/pdf/perf-vsphere-fault_tolerance.pdf - VMware vSphere™ 4 Fault Tolerance: Architecture and Performance

    http://www.vmware.com/files/pdf/resources/ft_virtualization_wp.pdf - Protecting Mission-Critical Workloads with VMware Fault Tolerance

    http://kb.vmware.com/kb/1010601 - Understanding VMware Fault Tolerance

    http://kb.vmware.com/kb/1013428 - VMware Fault Tolerance FAQ


    http://www.virtualizationteam.com/virtualization-vmware/vmware-esx-40-ft-fault-tolerant-sneak-peek.html - VMware ESX 4.0 FT – Fault Tolerant – Sneak Peek

    FT not supported on Nehalem systems with hyperthreading enabled?


    About vLockStep:




    Demo of VMware's vSphere Fault Tolerance (FT)



    FT requirements



    • Only some CPU can be used: http://kb.vmware.com/kb/1008027 - Processors and guest operating systems that support VMware Fault Tolerance

    • Hardware Virtualization (HV) must be enabled in the BIOS for each host in the cluster (but this is also required for EVC and x64 VMs)

    • The ESX hosts that run the primary and secondary Fault Tolerance nodes, must be running the same build of ESX.

    • All ESX 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.

    • Networking must be configured properly to ensure proper VMware Fault Tolerance functionality.

    • In some cases the VM must be powered off to enable FT (for some guest type and to convert vmdk from zeroedthick to eagerzeroedthick )


    To check compatibility there is also a VMware utility:

    Site Survey - http://www.vmware.com/download/shared_utilities.html



    FT 1.0 limitations



    FT 1.0 best practices

    • Use dedicated 1Gb (better if is 10Gbs) link for FT logging

    • Use SVMotion to converter from thin to thick, or use dastore browser/inflate (but in this case the VM must be powered off)

    • Use CPU with similar speed

    • Do not use CPU power management

    • With Nehalem CPU, HT could be enable without problem (and is also suggested by VMware)

    • Enable FT with the VM powered off


    See also: http://www.vmware.com/files/pdf/fault_tolerance_recommendations_considerations_on_vmw_vsphere4.pdf



    FT vs VM HA or MSCS

    FT does not protect against OS or application failures, only from ESX host failures.


    See also:

    Clarificaiton on Fault Tolerance




    VMware FT vs Marathon eveRun








    Enable/Disable FT with script

    Could be useful to implement some backup solution on FT protected VM.

    on-demand FT, can this be automated?

    ftCLI.pl - VMware Fault Tolerant Managment