windows server 2012 70-412认证释疑
Virtual Machine Manager (VMM) supports the following types of migration:(虚拟机迁移速度由上至下，逐步加快）
Network migration—This is the slowest type of migration and performs a network copy of the virtual machine data using BITS. The amount of downtime is in direct proportion to the size of the data transfer.
Quick migration—This type of migration is also known as cluster transfer, and can be used to migrate a highly available virtual machine. It leverages Windows Failover Cluster to migrate virtual machines between cluster nodes. The running state of the virtual machine is saved to disk (the virtual machine is hibernated), the disk is failed over to the other cluster node, and then the saved state is loaded to wake up the virtual machine. Downtime is minimal because quick migration takes a snapshot of the virtual machine and transfers data without requiring the virtual machine to be turned off.
Quick storage migration—Quick storage migration allows you to move virtual machine storage from one location to another. For example, you can move the storage for a virtual machine from a Fibre Channel SAN to an iSCSI SAN. The virtual disks of a running virtual machine can be migrated independent of storage protocols (SCSI, Fibre Channel) or storage types (local, DAS, SAN). Downtime is minimal because quick storage migration takes a snapshot of the virtual machine and transfers data without requiring the virtual machine to be turned off.
SAN migration—This type of migration uses SAN transfer to migrate virtual machines, and highly available virtual machines, into and out of a cluster. It can be used when both the source and destination hosts have access to the same storage infrastructure (LUN), and the storage can be transferred from one host to another. For SAN migration, the files for a virtual machine are not copied from one server to another and thus downtime is minimized. SAN migration can be used to copy a virtual machine from one host to another, or copying a virtual machine to or from the library. Note the following:
When you migrate a virtual machine into a cluster by using a SAN transfer, VMM checks that each node in the cluster can see the LUN, and automatically creates a cluster disk resource for the LUN.
To migrate a virtual machine out of a cluster, the virtual machine must be on a dedicated LUN that is not using CSV.
The following SAN infrastructures are supported for migration: Fiber Channel; iSCSI SANs; N_Port ID Virtualization (NPID).
Live migration—This type of migration moves a virtual machine running as part of a failover cluster from one cluster to another with no noticeable downtime for users or network applications.
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原文：http://acadia627.blog.51cto.com/3992605/1365997