Windows operating systems


Use the vmmaxpersnapshot option to specify the maximum number of virtual machines (VMs) to include in a Hyper-V snapshot. The VMs in the snapshot are backed up to the IBM Spectrum Protect™ server.

By increasing the number of VMs in a snapshot, you can reduce the number of snapshots that are taken for a backup operation. This capability reduces the scheduling contention that can be experienced during cluster backup operations of VMs on Clustered Shared Volumes (CSVs).

A snapshot with more VMs takes longer to complete and increases the load on the system. A larger number of VMs means that the snapshot persists longer, which can affect performance.

This option is valid only for Hyper-V backup operations on Windows Server 2012 and 2012 R2 operating systems.

Supported clients

This option is valid for all supported Windows clients. This option can also be defined on the server.

Options file

This option is valid in the client options file (dsm.opt) or on the command line for the Backup VM command. It can also be included on the server in a client option set. It cannot be set in the Preferences Editor.


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Specifies the maximum number of VMs that can be included in a Hyper-V snapshot. The default is 20. The maximum is 100. The minimum is 1.

If some VMs reside on local volumes and some VMs reside on Clustered Shared Volumes (CSVs), the number of VMs in a snapshot might be less than the vmmaxpersnapshot setting. A snapshot cannot contain a mixture of VMs on local and CSV volumes.

To avoid creating a snapshot that spans volumes, the number of VMs in a snapshot might be less than the maximum number if the VMs are on different volumes. For example, four VMs are on Volume A and one VM is on Volume B. A snapshot is taken with only four VMs (from Volume A) even though the maximum setting is five. A second snapshot is taken for Volume B.


Options file
vmmaxpersnapshot 10
Command line
dsmc backup vm -vmmaxpers=10