VCP 4 prep objective 7.2 – Enable a Fault tolerant Virtual Machine

Objective 7.2 – Enable a Fault tolerant Virtual Machine

Identify FT restrictions

  • Single vCPU
  • must reside in a HA cluster
  • must reside on shared storage
  • virtual disk must be thick provisioned (if RDM then must be virtual compatibility mode)
  • physical processors must be identical
  • no hot add support
  • no mscs
  • no NPIV
  • no svMotion
  • no snapshots
  • no support for vlance adapters
  • AMD-V or Intel-VT must be enabled

Evaluate FT use cases

mission critical applications, stateful applications or application not compatible with convential clustering.

Set up a FT  network

The best practice is to dedicate a VMKernel port just for Fault Tolerant logging.

Verify requirements of operating environment

Cluster requirements

  • VMware HA must be enabled
  • Host monitoring enabled
  • host certificate checking enabled on all hosts in the cluster
  • vMotion and Fault Tolerant logging VMKernel ports enabled
  • Hosts must be running the same ESX/ESXi version and patch level
  • Hosts must have shared access to the virtual machine datastores
  • Host must have identical network configuration
  • FT secondary virtual machines count towards the HA capacity calculations

Host requirements

  • Compatible processors as per KB1008027
  • Hardware mus tbe on the HCL
  • Virtualisation extensions must be enabled; Intel-VT or AMD-V
  • Valid ESX/ESXi licence

Virtual machine requirements

  • Shared storage
  • Thick provisioned disk (eager zeroed)
  • RDM using virtual compatibility mode
  • supported guest OS as per KB1008027

Enable FT for a virtual machine

Right click virtual machine > activate FT

NOTE: latency across the FT VMKernel network must be less than tenths of a second.

Test an FT configuration

vCenter > Hosts and Clusters view > Profile compliance tab > check compliance now

Upgrade ESX hosts containing FT virtual machines

(Ideally you would have four ESX/ESXi hosts)

  • vMotion FT virtual machines off two hosts
  • remove those two hosts from the cluster
  • upgrade those two hosts
  • disable FT on the primary virtual machines
  • vMotion virtual machines disabled in the step above
  • re-enable FT on the vMotioned virtual machines
  • repeat the above steps for the remaining two hosts

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