Storage Space Requirements for OSDP 7-Mode
UNIX: Space Requirements for the Volume Group
To avoid snapshot failures, 10% of the volume size must be free. To increase the copy-on-write (COW) cache size, add the nSnapCowSizeMB additional setting.
Windows: VSS Storage Space for Snapshot
You must set the initial storage space (minimum storage space) using the registry key MinDiffAreaFileSize. No maximum storage space is required. For more information on MinDiffAreaFileSize and requirements for specific Windows versions, see the Microsoft Windows Dev Center article Registry Keys and Values for Backup and Restore.