70-659 Part 16

Configuring Quick and Live Migrations

When planning for a Hyper-V cluster, certain requirements must be taken into account. Servers must be certified for Windows 2008 R2; SANs must support SCSI-3 persistent reservation (possible firmware upgrade needed).

For more information about cluster validation see the following blog:

http://blogs.technet.com/b/askcore/archive/2009/04/15/windows-2008-failover-cluster-validation-fails-on-validate-scsi-3-persistent-reservation.aspx

The host servers should have multiple network cards (NICs) and they should be dedicated to their respective tasks.

For example:

NIC1: can be used for parent partition communications.

NIC2: reserved for virtual network communications.

NIC3: can be reserved for Clustered Shared Volumes (CSV) traffic.

NIC4: can be reserved for Live Migration traffic.

The physical NICs should also have a minimum of 1GB. If you plan on implementing Multi-path I/O (MPIO) then more dedicated NICs will be needed. By having dedicated NICs, all communications are easier to manage; traffic will not overlap on a single card. This reduces potential bottlenecks and single points of failure.

For more information see the following blog post:

http://www.virtualizationteam.com/microsoft/hyper-v/live-migration-vs-quick-migration.html

Cluster Shared Volumes (CSV), are a new feature in Windows Server 2008 R2 Failover Clustering. Its purpose is to help simplify storage, reduce errors when dealing with multiple LUNs, and failovers. CSV is a special type of NTFS. CSVs are for Hyper-V only.

To enable CSV, Failover Clustering must first be installed. A LUN must be created and presented to every host in the cluster. Format the LUN accordingly. Once the LUN is formatted, add it to the cluster through the Failover Cluster Manager. Enabling CSV is done by right-clicking the cluster and choosing Enable Cluster Shared Volumes. You will get a warning message. Once enabled, you can then create a CSV by adding an already existing clustered disk. Name the CSVs appropriately.

Dynamic I/O redirection is a feature that is part of CSVs. Its purpose is to provide a redundant path for storage paths. For example, if a storage link goes down in a cluster, the CSV network will redirect the I/O. Without redirected I/O, VMs will come to a crashing halt. There will be some performance loss until the downed link is repaired. Redirected I/O can be enabled either manually or automatically, such as performing a backup of a CSV with Data Protection Manager.

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