Abstract: A Virtual Tape (VT) server residing on a network is connectible on its front end to a plurality of heterogeneous backup hosts, with different operating systems and/or backup applications, and on its back end to one or more disk storage devices in an open systems environment. The VT server responds to tape storage commands sent by the backup host as if it were the intended tape storage device and then emulates the desired tape storage activity on the one or more disk storage devices. In a described implementation, the host and server act as SCSI initiator and target and communicate over a Fibre Channel connection.

Abstract: Systems and methods enabling search of a repository for the location of data that is similar to input data, using a defined measure of similarity, in a time that is independent of the size of the repository and linear in a size of the input data, and a space that is proportional to a small fraction of the size of the repository. Additionally, remote operations are accomplished with significantly reduced system bandwidth by implementing remote differencing operations.