Because shadow migration requires committing new writes to the server prior to migration being complete, it is very important to test migration and monitor for any errors. Errors encountered during background migration are kept and displayed in the BUI as part of shadow migration status. Errors encountered during other synchronous migration are not tracked, but will be accounted for once the background process accesses the affected file. For each file, the remote filename as well as the specific error are kept. Clicking on the information icon next to the error count will bring up this detailed list. The error list is not updated as errors are fixed, but simply cleared by virtue of the migration completing successfully.
Shadow migration will not complete until all files are migrated successfully. If there are errors, the background migration will continually retry the migration until it succeeds. This allows the administrator to fix any errors (such as permission problems), let the migration complete, and be assured of success. If the migration cannot complete due to persistent errors, the migration can be canceled, leaving the local filesystem with whatever data was able to be migrated. This should only be used as a last resort; once migration has been canceled, it cannot be resumed.