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9.3 Migrating Virtual Machines
A running virtual machine can be migrated from its source virtual machine host to an-
other virtual machine host. This functionality is referred to as live migration. For live
migration the virtual machine being migrated must have access to its storage in exactly
the same location on both, source and destination host platforms.
Live migration only works when every entity involved has the same architecture. For
example, a 64-bit paravirtualized guest running on a 64-bit hypervisor can be migrated
to a host running a 64-bit hypervisor. If any of the pieces do not match exactly, migration
will fail.
Another requirement is, that the involved file systems are available on both machines.
The options to accomplish this task include Network Block Devices (NBD),
iSCSI, NFS, DRBD and fiber channel devices. Furthermore, the routing of the network
connection to the virtual network device must be correct.
The following xend options, which are located in the /etc/xen/xend-config
.sxp file, need to be set on both hosts to make live migration work.
(xend-relocation-server yes)
(xend-relocation-port 8002)
(xend-relocation-address ")
(xend-relocation-hosts-allow ")
For information on modifying xend settings, see Section 5.2, "Controlling the Host by
Modifying Xend Settings" (page 36). For more details about using xm to migrate VM
Guest systems, see Section 5.6, "Migrating Xen VM Guest Systems" (page 41).
9.4 Passing Key Combinations to
Virtual Machines
In a virtual machine window, some key combinations, such as Ctrl + Alt + F1 , are rec-
ognized by the virtual machine host but are not passed to the virtual machine. To bypass
the virtual machine host, Virtual Machine Manager provides sticky key functionality.
Pressing Ctrl , Alt , or Shift three times makes the key sticky, then you can press the re-
maining keys to pass the combination to the virtual machine.
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Virtualization with Xen
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