In the off-host backup mode, backup processing is shifted from the source Hyper-V host to a dedicated machine – an off-host backup proxy. The off-host backup proxy acts as a “data mover”– the Veeam transport service running on it retrieves VM data from the source datastore, processes it and transfers to the destination. This type of backup does not impose load on the Hyper-V host — while resource intensive backup operations are performed on the off-host backup proxy, production hosts remain unaffected. To learn more, see Off-Host Backup Proxy.
To perform off-host backup, Veeam Backup & Replication uses transportable shadow copies. The transportable shadow copy technology enables you to create a snapshot of a data volume on one server and import, or mount, it onto another server within the same subsystem (SAN) for backup and other purposes. The transport process is accomplished in a few minutes, regardless of the amount of the data. The process is performed at the SAN storage layer so it does not impact the host CPU usage or network performance. To learn more, see http://technet.microsoft.com/en-us/library/ee923636(v=ws.10).aspx.
To be able to perform off-host backup, you must meet the following requirements:
|1.||You must configure an off-host backup proxy. The role of an off-host backup proxy can be assigned only to a physical Microsoft Windows 2008 Server R2 machine with the Hyper-V role enabled, Microsoft Windows Server 2012 machine with the Hyper-V role enabled or Microsoft Windows Server 2012 R2 machine with the Hyper-V role enabled. |
Note that the version of the Hyper-V host and off-host backup proxy must coincide. For example, if you use a Microsoft Windows 2008 Server R2 machine with the Hyper-V role enabled as a Hyper-V host, you should deploy the off-host backup proxy on a Microsoft Windows 2008 Server R2 machine with the Hyper-V role enabled.
|3.||The source Hyper-V host and the off-host backup proxy must be connected (through a SAN configuration) to the shared storage.|
|4.||To create and manage volume shadow copies on the shared storage, you must install and properly configure a VSS hardware provider that supports transportable shadow copies on the off-host proxy and Hyper-V host. Typically, when configuring a VSS hardware provider, you need to specify a server controlling the LUN and disk array credentials to provide access to the array. |
The VSS hardware provider is usually distributed as a part of client components supplied by the storage vendor. Any VSS hardware provider certified by Microsoft is supported. Note that some storage vendors may require additional software and licensing to be able to work with transportable shadow copies.
|5.||If you back up VMs whose disks reside on a CSV with Data Deduplication enabled, make sure that you use a Microsoft Windows 2012 R2 machine as an off-host backup proxy and enable the Data Deduplication option on this off-host backup proxy. Otherwise, off-host backup will fail.|
The off-host backup process includes the following steps:
|1.||Veeam Backup & Replication triggers a snapshot of the necessary volume on the production Hyper-V host. |
|2.||The created snapshot is split from the production Hyper-V server and mounted to the off-host backup proxy.|
|3.||The Veeam transport service running on a backup proxy uses the mounted volume snapshot to retrieve VM data; the VM data is processed on the proxy server and copied to the destination.|
|4.||Once the backup process is complete, the snapshot is dismounted from the off-host backup proxy and deleted on the SAN.|
If you plan to perform off-host backup for a Hyper-V cluster with CSV, make sure you deploy an off-host backup proxy on a host that is NOT a part of a Hyper-V cluster.
When a volume snapshot is created, this snapshot has the same LUN signature as the original volume. Microsoft Cluster Services do not support LUNs with duplicate signatures and partition layout. For this reason, volume snapshots must be transported to an off-host backup proxy outside the cluster. If the off-host backup proxy is deployed on a node of a Hyper-V cluster, a duplicate LUN signature will be generated, and the cluster will fail during backup or replication.
|▪||Links to resources and documentation from some of storage vendors:|
|•||EMC (Clarion and Symmetrix): http://powerlink.emc.com/ (account required). Go to Support > Software downloads and licensing > Downloads T-Z > VSS Provider.|
To get detailed information, contact your storage vendor.