All of the technologies we have discussed so far operate internally to a system. They perform their backup and restore operations from the inside of a running machine. In the following sections we will explore some data protection technologies that operate externally and some of the situations that make that capability necessary.
Companies that have acquired a lot of virtual machines may have to consider doing some of their image backups at the hypervisor level. Many virtual appliances do not provide a built-in means of backup, or perhaps only a configuration dump, and many others have only a management interface for the network port and no backup capability at all.