The MaxShadowCopies registry value specifies the maximum number of client-accessible shadow copies that can be stored on each volume of the computer. A client-accessible shadow copy is a shadow copy that is created using the VSS_CTX_CLIENT_ACCESSIBLE value of the _VSS_SNAPSHOT_CONTEXT enumeration. Client-accessible shadow copies are used by Shadow Copies for Shared Folders. For more information about shadow copies, see the VSS documentation.
If the MaxShadowCopies registry value does not exist, the backup application can create it under the following registry key:
Create a value with the name MaxShadowCopies and type DWORD. The default data for this value is 64. The minimum is 1. The maximum is 512.
For other types of shadow copies, there is no registry value that corresponds to MaxShadowCopies. The maximum number of shadow copies is 512 per volume.
Note The MaxShadowCopies setting is supported on Windows Server 2003 or later.
Windows Server 2003: On cluster servers, MaxShadowCopies registry value’s data may need to be set to a lower number. For more information, see „When you use the Volume Shadow Copy Service on Windows Server 2003-based computers that run many I/O operations, disk volumes take longer to go online“ in the Help and Support Knowledge Base at https://support.microsoft.com/kb/945058.