For best performance, consider the following best practices for a Hyper-V environment that is protected by the Hyper-V Agent.
Enable CSV Cache
In a failover cluster, enabling the CSV cache might improve Hyper-V Agent backup performance. Microsoft recommends enabling the CSV cache for read-intensive workloads. See “Use Cluster Shared Volumes in a Failover Cluster” (http://technet.microsoft.com/en-us/library/jj612868.aspx) and “How to Enable CSV Cache” (http://blogs.msdn.com/b/clustering/archive/2012/03/22/10286676.aspx).
Clean up snapshots and checkpoints before backups
The Hyper-V Agent backs up and restores user-level snapshots or checkpoints with VMs, which can take a significant amount of time.
Note: “Snapshots” in Windows 2012 are the same as “checkpoints” in Windows Server 2012 R2.
Consistent with Microsoft best practices, we recommend not taking user-level snapshots or creating checkpoints of VMs that will be backed up in a production environment, except in a transient fashion. When it is necessary to take a snapshot or create a checkpoint of a protected VM, remove the snapshot or checkpoint before the next backup. See “Hyper-V: Avoid using snapshots on a virtual machine that runs a server workload in a production environment” (http://technet.microsoft.com/en-us/library/ee941140(v=ws.10).aspx).
Use fixed-size VHDXs or VHDs
If a VM includes a dynamically expanding virtual hard disk (VHDX or VHD), an incremental backup might be as large as a seed backup.
Consistent with Microsoft best practices, we recommend not using dynamically expanding VHDXs or VHDs in a production environment. See “Hyper-V: VHD-format dynamic virtual hard disks are not recommended for virtual machines that run server workloads in a production environment” (http://social.technet.microsoft.com/wiki/contents/articles/13078.hyper-v-vhd-format-dynamic-virtual-hard-disks-are-not-recommended-for-virtual-machines-that-run-server-workloads-in-a-production-environment.aspx).
Avoid using VMs with limited or no backup support
The Hyper-V Agent has limited support for VMs that contain:
•Virtual disks which are configured as dynamic disks by Windows Disk Management (within a VM)
•FAT or FAT32 volumes
•Linux guest OS
•No Hyper-V Integration Services running
During a backup, Hyper-V puts these VMs into a saved state for a brief period of time while capturing a VSS snapshot. The backup will be crash-consistent (not application-consistent). See “Planning for Backup” (http://technet.microsoft.com/en-us/library/dd252619(WS.10).aspx).
During a backup, the Hyper-V Agent skips VMs that contain mixed storage or share virtual hard disks.