NOTICE: For documentation on JetBackup version 3.3 and greater please visit: http://docs.jetbackup.com
A partially completed job usually means that something happened during the job with one (or more) of the accounts in the backup list. The backup continued and skipped the problematic account(s), and wrote the related information about it in the job log.
This is usually a minor issue, that doesn’t disturb the whole backup process. It can be further checked under the backup job logs: JBM Top menu -> Logs -> Job logs