- CPU compatibility with FT
The vLockstep technology used by FT requires the physical processor extensions added to the latest processors from Intel and AMD. In order to run FT, a host must have an FT-capable processor, and both hosts running an FT VM pair must be in the same processor family. The following table shows which CPUs are compatible with FT and can be used toegther in an FT VM pair. If an FT cluster mixes multiple processor types, they must be able to work together as shown by a green circle O where those the two processor types intersect in the table.
Intel 3100 O O O O X O X X X Intel 3300 O O O O X O X X X Intel 5200 O O O O X O X X X Intel 5400 O O O O X O X X X Intel 5500 X X X X O X X X X Intel 7400 O O O O X O X X X AMD 1300 X X X X X X O O O AMD 2300 X X X X X X O O O AMD 8300 X X X X X X O O O
- CPU Speeds and FT
When ESX hosts are used together in an FT cluster, their processor speeds must be matched fairly closely to ensure that the hosts can stay in sync. VMware SiteSurvey will flag any CPU speeds that are different by more than 400 MHz.
- Compatible CPU Steppings and FT
This issue has been fixed by a patch: the patch bulletin ID for ESX is ESX400-200906401-BG, and for ESXi is ESXi400-200906401-BG. VUM customers are automatically notified when patches such as these are released. Customers not using VUM can download this patch from http://support.vmware.com/selfsupport/download/.
Without the above patch, when the Primary and Secondary VMs for FT are run on hosts with mixed steppings of Intel Xeon 5400 or 5200 Series Processors (CPUID Family 6, Model 23, steppings 6 and 10), the Secondary VM starts for a few seconds and then fails with the Primary VM going into the "Need Secondary VM" state. To avoid this issue, install the patch or ensure that the processors within the host system match.
- ESX Versions and Build Numbers required by FT
ESX hosts running the FT VM pair must be running at least ESX 4.0, and must be running the same build number of ESX.
- Pairing ESX servers for FT
FT requires at least two (three recommended) compatible ESX servers. See the above table to determine which CPU types can be paired together. In addition, ESX hosts must be running the same version of ESX to be paired together for FT.
- BIOS settings for FT
FT uses hardware virtualization, so the BIOS settings for each ESX host must have that support enabled. It is not always possible for VMware SiteSurvey to determine the BIOS settings. When the BIOS settings can be detected, VMware SiteSurvey may flag them as a problem for one of the following reasons:
The server is running a VMware product other than ESX or ESXi.
The ESX server does not support hardware virtualization, which is required for FT.
The ESX server does support FT, but virtualization has been disabled in the BIOS, which prevents FT from running.
The ESX server has a BIOS option set that enforces a maximum limit on the CPUID, which prevents FT from running.
The ESX server BIOS needs to be updated for FT to work.
An unknown BIOS configuration is preventing FT from working properly.
? VMware SiteSurvey displays this question mark for the BIOS Settings item in a report when it is unable to check the settings. The HV capability must be enabled in order to use FT with a VM on that server.
- Physical NIC Requirements for FT
FT requires each member of the FT cluster to have a minimum of two NICs with speeds of at least 1 Gb/S. Each NIC must also be on the same network.
? VMware SiteSurvey displays this question mark when it is unable to determine the physical NIC settings. This can happen if the NIC is configured to auto negotiate the speed.
- Virtual NIC Requirements for FT
FT requires each member of the FT cluster to have two virtual NICs, one for logging and one for vmotion. VMware SIteSurvey will flag ESX hosts which do not contain as least two virtual NICs.
? VMware SiteSurvey displays this question mark when it is unable to determine the virtual NIC settings. This can happen when the ESX server is running an older version of ESX.
- Shared Storage Required for FT
ESX hosts used together as an FT cluster must share storage for the protected Virtual Machines. For this reason VMware SiteSurvey lists the shared storage it detects for each ESX host and flags hosts which do not have any shared storage in common. In addition, an FT-protected VM must itself be stored on shared storage and any disks connected to it must be shared storage.
- Multi-Processor Virtual Machines and FT
At this time, FT only supports single processor virtual machines. VMware SiteSurvey flags virtual machines that are configured with more than one processor. To use FT with those VMs, you must reconfigure them as single-CPU VMs.
- Thin-provisioned Disks and FT
FT will not work with virtual disks backed with thin-provisioned storage or disks that do not have clustering features enabled. When you turn on FT, the conversion to the appropriate disk format is performed by default. The virtual machine must be in a powered-off state to take this action.
- Snapshots and FT
Snapshots must be removed before FT can be enabled on a virtual machine. In addition, it is not possible to take snapshots of virtual machines on which FT is enabled.
- License for FT
VMware SiteSurvey verifies that each ESX host is licensed to use the FT feature.
- Guest Operating Systems and FT
Most combinations of Guest operating system and processor types work well with FT. The following exceptions are not supported with AMD Barcelona CPUs:
- Windows XP (64 bit)
- Windows XP (32 bit)
- Windows 2000
- Solaris 10 (32 bit)
- Physical Raw Disk Mapping and FT
Physical Raw Disk Mapping (RDM) is not supported with FT. You may only use virtual RDMs.
- Paravirtualization and FT
Paravirtualized guests are not supported with FT. To use FT with a virtual machine with this issue, reconfigure the virtual machine without a VMI ROM.
- NPIV and FT
N_Port ID Virtualization (NPIV) is not supported with FT. To use FT with a virtual machine with this issue, disable the NPIV configuration of the virtual machine.
- CD-ROM or Floppy Drives and FT
FT is not supported with virtual machines that have CD-ROM or floppy virtual devices backed by a physical or remote device. To use FT with a virtual machine with this issue, remove the CD-ROM or floppy virtual device or reconfigure the backing with an ISO installed on shared storage.
- Legacy Network Interfaces and FT
FT is not compatible with some legacy network hardware. While some legacy drivers are supported, FT does not support the vmxnet2 driver. You might need to install VMware tools to access the vmxnet2 driver instead of vlance in certain guest operating systems.
? VMware SiteSurvey displays this question mark when it is unable to determine if legacy drivers are in use or if there is a potential issue due to the use of the vmxnet2 driver.
- NIC Passthrough and FT
The NIC passthrough feature is not support with FT and must be turned off before FT can be enabled for that virtual machine.
About VMware SiteSurveyVersion 1.0
VMware SiteSurvey is a utility which analyzes a cluster of ESX hosts and reports on whether the configuration of both software and hardware is suitable for use with the VMware Fault Tolerance (FT) feature. The VMware SiteSurvey tool is available for download at http://www.vmware.com/download/shared_utilities.html. Version 1.0 is the latest version.
For questions or comments about this tool, contact the VMware SiteSurvey team at: firstname.lastname@example.org.
In order to use VMware SiteSurvey, you must have first defined a cluster of ESX hosts in Virtual Center. When you run VMware SiteSurvey, it will prompt you for your Virtual Center location, credentials, and for which cluster you want surveyed.
As VMware SiteSurvey is gathering information about your ESX hosts, it compares the configuration details against the requirements for using the FT feature. (You can read an overview of the VMware Fault Tolerance feature here.) The resulting report shows a complete list of configuration items reviewed, along with an indication on whether that item requires attention before using FT.
Each of the configuration items checked by VMware SiteSurvey
is described below.
VMware SiteSurvey Configuration Checks