Novell LINUX ENTERPRISE SERVER 11 - VIRTUALIZATION Manual page 48

4.6.2 Preparing Block Devices for Migrations
The block devices needed by the VM Guest system must be available on all involved
VM Host Server systems. This is done by implementing some kind of shared storage
that serves as container for the root file system of the migrated VM Guest system.
Common possibilities include:
• iSCSI can be setup to give access to the same block devices from different systems
at the same time. For more information about iSCSI, see
.com/documentation/sles11/stor_admin/data/cha_inst_system
_iscsi.html.
• NFS is a widely used root file system that can easily be accessed from different
locations. For more information, see Chapter 25, Sharing File Systems with NFS
(↑Administration Guide).
• DRBD can be used, if only two VM Host Server systems are involved. This gives
some extra data security, because the used data is mirrored over the network. For
more information, see
sles11/book_sleha/data/cha_ha_drbd.html.
• SCSI can also be used, if the available hardware permits shared access to the same
disks.
4.6.3 Migrating VM Guest Systems
The actual migration of the VM Guest system is done with the command:
xm migrate --live <domain_name> <host>
The option --live must be set to migrate a system that is currently running.
The speed of the migration depends on how fast the memory print can be saved to disk,
sent to the new VM Host Server and loaded there. This means, that small VM Guest
systems can be migrated faster than big systems with a lot of memory.
38 Virtualization with Xen
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