During the migration either to or from a cluster server, the shared cluster resource where the agents are deployed becomes full.
During the migration, .prv and .pub files are placed within the Migration Manager shares for processing. These can require large amounts of disk space, which if unavailable can cause issues.
To resolve this disk space issue there are two possible solutions:
1.) Stop all agents running on the server.
2.) Copy the entire Migration Manager agent directory out of the current location on the cluster resource to another location.
2.) Remove the cluster resource from the cluster server taking note the drive letter.
3.) Setup a new cluster resource with increased storage using the exact same drive letter, permissions etc, and copy the data back to this location. Then re-create the share as it was originally setup.
The other method involves the same backup procedure as Option #1, then uninstalling all agents from the cluster. This can be done by right clicking the Exchange Migration Project and choosing the install/uninstall agents option, then walking through the wizard for each agent installed upon the cluster. Then re-install all the agents to the new location, copying any .prv, or .pub files from the backup to the same location in the newly created directory structure.