VMware FT is a wonderfull feature but it has so many restrictions and requirements…phew!
- CPUs: Limited processors must be the same family (no mix/match)
Requires Intel 31xx, 33xx, 52xx, 54xx, 55xx, 74xx or AMD 13xx,23xx, 83xx series of processors
SMP virtual machines are not supported.
- Hardware Virtualization must be enabled in the BIOS.
- Hosts must be in a VMware High Availability enabled cluster.
- Storage: shared storage (FC, iSCSI, or NAS).
- Network: minimum of 3 NICs for various types of traffic (ESX Management/VMotion, virtual machine traffic, FT logging).
- GigE required for VMotion and FT logging.
- Minimized single points of failures in the environment. For example, NIC teaming, multiple network switches, storage multipathing.
- Primary and secondary hosts must be running the same build of ESX.
- The primary and secondary fault tolerant virtual machines must be in a VMware HA cluster.
- Primary and secondary virtual machines must not run on the same host. FT automatically places the secondary virtual machine on a different host.
- Virtual machine files must be stored on shared storage.
- Shared storage solutions include NFS, FC, and iSCSI.
- For virtual disks on VMFS-3, the virtual disks must be thick, meaning they cannot be thin or sparsely allocated.
- Turning on VMware FT automatically converts the virtual machine to thick-eager zeroed disks.
- Virtual Raw Disk Mapping (RDM) is supported. Physical RDM is not supported.
- Multiple gigabit Network Interface Cards (NICs) are required.
- A minimum of two VMKernel Gigabit NICs dedicated to VMware FT Logging and VMotion.
- The FT Logging interface is used for logging events from the primary virtual machine to the secondary FT virtual machines.
- For best performance, use 10Gbit NIC rather than 1Gbit NIC, and enable the use of jumbo frames.
- VMware FT requires that Hardware Virtualization (HV) be turned on in the BIOS. The process for enabling HV varies among BIOSs. Contact your vendor for specifics.
From another VMware.com KB
For VMware FT to be supported, the servers that host the virtual machines must each use a supported processor from the same category as documented below:
Intel Xeon based on 45nm Core 2 Microarchitecture Category:
- 3100 Series
- 3300 Series
- 5200 Series (DP)
- 5400 Series
- 7400 Series
Intel Xeon based on Core i7 Microarchitecture Category:
- 5500 Series
AMD 3rd Generation Opteron Category:
- 1300 Series
- 2300 Series (DP)
- 8300 Series (MP)
To summarize all the FT gotchas, have a look at this link VMware Fault Tolerance Requirements and Limitations. Long list isn’t it :O