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Live migration is probably the most important technology that Microsoft has added to Hyper-V in Windows Server 2008 R2. It enables virtual machines (VMs) to be moved between Hyper-V hosts with no downtime. Using live migration, you can migrate all VMs off the Hyper-V host that needs maintenance, then migrate them back when the maintenance is done. In addition, live migration enables you to respond to high resource utilization periods by moving VMs to hosts with greater capacities, thereby enabling the VM to provide end users with high levels of performance even during busy periods.

      Live migrations can be manually initiated, or if you have System Center Virtual Machine Manager 2008 R2 and System Center Operations Manager 2007, you can run automated live migrations in response to workload. You need to complete quite a few steps to set up two systems for live migration, and I’ll guide you through the process. First, I’ll explain how live migration works. Then I’ll cover some of the hardware and software prerequisites that must be in place. Finally, I’ll walk you through the important points of the Hyper-V and Failover Clustering configuration that must be performed to enable live migration.

The Windows Server 2008 Failover Clustering feature provides high availability for services and applications. To ensure applications and services remain highly available, it is imperative the cluster service running on each node in the cluster function at the highest level possible. Providing redundant and reliable communications connectivity among all the nodes in a cluster plays a large role in ensuring for the smooth functioning of the cluster. Configuring proper communications connectivity within a failover cluster not only provides access to highly available services required by clients but also guarantees the connectivity the cluster requires for its own internal communications needs. The sections that follow discuss Windows Server 2008 Failover Clustering networking features, functionality and recommended processes for the proper configuration and implementation of network connectivity within a cluster.

The following sections provide the information needed to understand failover cluster networking and to properly implement it.

Microsoft Windows Hyper-V Server 2008 R2 is a free version much like Windows Server 2008 R2 Core, except it comes with the Hyper-V role preconfigured.

The only thing you will have to take in consideration before installing such a server is that Hyper-V Server 2008 R2 only comes with a PowerShell/CMD-prompt. So to configure such a server you should learn some Windows commands and PowerShell cmdlets.

Hyper-V虚拟机给我们带来了诸多便利，比如应用程序整合、节能、节约成本、提高资源利用率等等。随着Hyper-V虚拟机的推广，用户的使用越来越普及。很多用户在Hyper-V虚拟机中用到了MS SQL Server。但是单独（standalone）的SQL Server 不能提供高可用性和灾难恢复的功能。在对可用性有较高要求的Hyper-V用户面前，故障转移群集（Failover cluster）是必然用到的功能。当虚拟的生产服务器宕机时，热备份中的虚拟的服务器可以很快投入工作中。 然而在虚拟机上搭建故障转移群集比在物理机上搭会有更多种组合。