Information Technology Reference
In-Depth Information
the VM is not rebooted during a vMotion, the guest assumes the CPU instruction set on
the target host is the same as on the source host. You can get away with slightly dissimilar
processors, but in general the processors in two hosts that perform vMotion must meet the
following requirements:
CPUs must be from the same vendor (Intel or AMD).
◆
CPUs must be from the same CPU family (Xeon 55xx, Xeon 56xx, or Opteron).
◆
CPUs must support the same features, such as the presence of SSE2, SSE3, and SSE4
and NX or XD (see the sidebar “Processor Instruction”).
◆
For 64-bit VMs, CPUs must have virtualization technology enabled (Intel VT or
AMD-v).
◆
We'll talk more about processor compatibility in the section “Ensuring vMotion
Compatibility.”
Processor Instruction
Streaming SIMD Extensions 2 (SSE2) was an enhancement to the original Multimedia Extension
(MMX) instruction set found in the PIII processor. h e enhancement targeted the fl oating-point
calculation capabilities of the processor by providing 144 new instructions. SSE3 instruction sets
are an enhancement to the SSE2 standard targeting multimedia and graphics applications. SSE4
extensions target both the graphics and the application server.
AMD's Execute Disable (XD) and Intel's NoExecute (NX) are features of processors that mark
memory pages as data only, which prevents a virus from running executable code at that address.
h e operating system needs to be written to take advantage of this feature, and in general, versions
of Windows starting with Windows 2003 SP1 and Windows XP SP2 support this CPU feature.
h e latest processors from Intel and AMD have specialized support for virtualization. h e AMD-V
and Intel Virtualization Technolog y ( V T) must be enabled in the BIOS in order to create 64 -bit VMs.
In addition to the vMotion requirements for the hosts involved, the VM must meet the fol-
lowing requirements to be migrated:
The VM must not be connected to any device physically available to only one ESXi host.
This includes disk storage, CD/DVD drives, l oppy drives, serial ports, and parallel ports.
If the VM to be migrated has one of these mappings, simply deselect the Connected check
box beside the offending device. For example, you won't be able to migrate a VM with
a CD/DVD drive connected; to disconnect the drive and allow vMotion, deselect the
Connected box.
◆
The VM must not be connected to an internal-only virtual switch.
◆
The VM must not have its CPU afi nity set to a specii c CPU.
◆
The VM must have all disk, coni guration, log, and nonvolatile random access memory
(NVRAM) i les stored on a VMFS or NFS datastore accessible from both the source and the
destination ESXi hosts.
◆
