Technical information
VMware, Inc. 37
Chapter 4 Virtual Infrastructure Management
VMware VMotion and Storage VMotion
ξ ESX 4.0 introduces virtual hardware version 7. Because virtual machines running on hardware version 7
canβt run on prior versions of ESX, they can be moved using VMware VMotion only to other ESX 4.0 hosts.
ξ Before using VMware Storage VMotion make sure you have sufficient storage bandwidth between the
ESX host where the virtual machine is running and both the source and destination storage arrays. This
is necessary because the virtual machine will continue to read from and write to the source storage array,
while at the same time the virtual disk to be moved is being read from the source storage array and written
to the destination storage array. While this is happening, both storage arrays may have other traffic (from
other virtual machines on the same ESX host, from other ESX hosts, etc.) that can further reduce the
effective bandwidth.
With insufficient storage bandwidth, Storage VMotion can fail. With barely sufficient bandwidth, while
Storage VMotion will succeed, its performance might be poor.
ξ When possible, schedule Storage VMotion operations during times of low storage activity, when available
storage bandwidth is highest. This way Storage VMotion will have the highest performance.