Specifications

Migration with vMotion
Migration with vMotion™ allows virtual machine working processes to continue throughout a migration.
The entire state of the virtual machine, as well as its configuration file, if necessary, is moved to the new host,
while the associated virtual disk remains in the same location on storage that is shared between the two hosts.
After the virtual machine state is migrated to the alternate host, the virtual machine runs on the new host.
The state information includes the current memory content and all the information that defines and identifies
the virtual machine. The memory content includes transaction data and whatever bits of the operating system
and applications are in the memory. The defining and identification information stored in the state includes
all the data that maps to the virtual machine hardware elements, such as BIOS, devices, CPU, MAC addresses
for the Ethernet cards, chip set states, registers, and so forth.
When you migrate a virtual machine with vMotion, the new host for the virtual machine must meet
compatibility requirements in order for the migration to proceed.
Migration with vMotion happens in three stages:
1 When the migration with vMotion is requested, vCenter Server verifies that the existing virtual machine
is in a stable state with its current host.
2 The virtual machine state information (memory, registers, and network connections) is copied to the target
host.
3 The virtual machine resumes its activities on the new host.
If any error occurs during migration, the virtual machines revert to their original states and locations.
Migration of a suspended virtual machine and migration with vMotion can be referred to as hot migration,
because they allow migration of a virtual machine without powering it off.
Host Configuration for vMotion
In order to successfully use vMotion, you must first configure your hosts correctly.
Ensure that you have correctly configured your hosts in each of the following areas:
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Each host must be correctly licensed for vMotion.
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Each host must meet shared storage requirements for vMotion.
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Each host must meet the networking requirements for vMotion.
IMPORTANT The ESXi firewall in ESXi 5.0 does not allow per-network filtering of vMotion traffic. Therefore,
you must install rules on your external firewall to ensure that no incoming connections can be made to
the vMotion socket.
vMotion Shared Storage Requirements
Configure hosts for vMotion with shared storage to ensure that virtual machines are accessible to both source
and target hosts.
During a migration with vMotion, the migrating virtual machine must be on storage accessible to both the
source and target hosts. Ensure that the hosts configured for vMotion use shared storage. Shared storage is
typically on a storage area network (SAN), but can also be implemented using iSCSI and NAS shared storage.
See the VMware SAN Configuration Guide for additional information on SAN and the vSphere Storage for
information on other shared storage.
Chapter 12 Migrating Virtual Machines
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