When you use SMS to migrate a source server running Windows, the disks on the target server should be at least the size recommended on the Source Management page. Otherwise, the migration may fail. If you have created a target server running Windows, and the disks on the target server are too small, you can shrink the source server disks to be no larger than the target server disks.
For a migration to be successful, the target server disks must be at least as large as the source disks. If they are not, you need to either scale up the target server disk or shrink the source server disk. On a Windows server, you can shrink disk partitions of the source server using the Windows Disk Management tool.
The Disk Management tool is displayed.
The Shrink Volume dialog box is displayed.


The new space available is displayed as unallocated space. Figure 1 Disk partition after shrink
The SMS console is displayed.