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VCAP-DCA Study Notes – 4.2 Deploy and test VMware FT

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The main document to work through for the VCAP-DCA is the Availability Guide but there are plenty of good white papers and blog posts which give useful background information (see the bottom of this post). If you have access to the 2010 VMworld content it’s worth watching session BC8274 which covers most of the material on the blueprint.

Knowledge

  • Identify VMware FT hardware requirements
  • Identify VMware FT compatibility requirements

Skills and Abilities

  • Modify VM and ESX/ESXi Host settings to allow for FT compatibility
  • Use VMware best practices to prepare a vSphere environment for FT
  • Configure FT logging
  • Prepare the infrastructure for FT compliance
  • Test FT failover, secondary restart and application fault tolerance in a FT Virtual Machine

FT requirements (hardware, software and feature compatibility)

Compatibility
  • Firstly you have to make sure your host hardware will support FT – it’s more demanding than many other VMware features.
    • The main requirement is to have Intel Lockstep technology support in the CPUs and chipset. Rather than list the processor families which support FT you can read VMwareKB1008027.
    • Hardware virtualisation must also be enabled in the BIOS (not always on by default).
  • You need to ensure the guest OS and CPU combination is supported (as the Availability Guide states, Solaris on AMD is not for example).
  • Must have HA enabled on the cluster
  • Licencing– you need Advanced or higher to run FT
  • Host certificates need to be enabled. If you did a clean install of vSphere 4.x this is enabled by default but if you upgraded from VI3.x you have to explicitly enable it (vCentre settings, SSL)
  • Should avoid mixing ESX and ESXi hosts in a cluster with FT-enabled VMs (VMwareKB1013637)

There are also VM level requirements;

  • No USB or sound devices
  • No NPIV
  • No paravirtualized guest OS
  • No physical mode RDMs
  • Hot plug (memory, CPU, hard disks etc) is automatically disabled for FT-enabled VMs
  • No Serial or parallel ports
Restrictions

FT places quite a few restrictions on the features you can use;

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