Achieve Zero Downtime with Fault Tolerance
- FT provides continuous availability for a VM ( or ,zero Downtime )
- Takes VMHA to the next level
- Works for all applications and 99% of guests operating systems
- Does this by reating a "live shadow" copy of the running VM then keeping them in
"lockstep" suing VMware's vLockstep
- If an ESX server fails, the shadow will take over and a new shadow will take over and a new shadow will be
created in the cluster on another ESX server
- Primary VM is called the "Primary" and the copied /lookstep VM is the "secondary"
- The vitual disk for the VM is on shared storage and never moves
- "Continuous VMotion"
Requirements of FT
- CPUs on all FT ESX servers must match and be from a specific list of processors ( see KB )
- Hardware virtualization enabled in the BIOS
- Hosts must be in a HA cluster
- Recommended minimum # of 1GB NICs = 3
- ESX servers must be running same build
- VM's on shared SAN, accessible by servers
- Vsphere Adanced, Enterprise, or Ent plus
Constraints of FT
- single vCPU in each VM only ( no SMP )
- Requires specific hardware
- Recommented minimum of 4 VMs running FT on an ESX server
- "line of site" between ESX servers due to latency
- Only Thick disk is supported
- Snapshots are not allowed
- Some guests not supported and some guests require shutdown to enable
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