Abstract: A storage system including journaling comprises a controller capable of coupling to at least one storage device and to at least one journaling device, and a process executable on the controller. The executable process comprises a resolve utility capable of determining logical unit, track, and sector identification for a selected file on the at least one storage device, a user interface enabling a user to select tracks and sectors on the at least one storage device for restoration to a predetermined point in time, and a restoration utility. The restoration utility accesses data corresponding to the selected tracks and sectors from the journaling device and restores the data to the track and sector locations of the storage device to the predetermined point in time.

Abstract: A disk array having an internal mirror architecture may include: a plurality of disk drives configured to provide a primary logical storage device (LDEV), a first instance of an internally-mirroring secondary LDEV and a second instance of an internally-mirroring secondary LDEV.

Abstract: A pulse width of a pulse having a nominal pulse width is modulated in accordance with a digital value to be communicated. The number of clock cycles that the modulated pulse width exceeds the nominal pulse width is counted. Various embodiments use a counter to determine the extent that the modulated pulse exceeds the nominal pulse width. The counter is initialized to a value (P) upon detection of a first edge of the extended pulse. The counter is configured to rollover or is reset when the counter reaches a count of P+M, where M represents the nominal pulse width count. In various embodiments, P is zero. The counter is halted upon detection of a second edge of the extended pulse. The resulting count represents the digital data value.

Abstract: A pulse width of a pulse having a nominal pulse width is modulated in accordance with a digital value to be communicated. The number of clock cycles that the modulated pulse width exceeds the nominal pulse width is counted. Various embodiments use a counter to determine the extent that the modulated pulse exceeds the nominal pulse width. The counter is initialized to a value (P) upon detection of a first edge of the extended pulse. The counter is configured to rollover or is reset when the counter reaches a count of P+M, where M represents the nominal pulse width count. In various embodiments, P is zero. The counter is halted upon detection of a second edge of the extended pulse. The resulting count represents the digital data value.

Abstract: An apparatus, method, computer readable medium and logical device have been created for storing essentially only modified or changed information from one of a pair of mirrored storage devices. In one exemplary embodiment, essentially only tracks of information from a primary volume of a mirrored pair of mirrored storage units, which have been modified since creation of the mirror, need be stored. In another exemplary embodiment, essentially only tracks of information from a primary volume of a mirrored pair of mirrored storage units, which have been modified since a last resynchronization, need be stored. In yet another exemplary embodiment, essentially only tracks of information from a primary volume of a mirrored pair of mirrored storage units, which have been modified since a last command, need be stored. By storing actual information which was modified and by storing essentially only information which was modified, a small amount of actual information need be stored.

Abstract: An interface technology is disclosed by which an application program running on a host can invoke a command to cause a third party copy engine (“3PCE”) to carry out a desired copy operation without actually generating the command needed by the 3PCE. A first code arrangement is provided, receipt of which causes a processor to generate a second code arrangement representing a third party copy command and its corresponding parameters. Also, a liaison system and method are provided. The liaison system is interposed between an application program running on a host and a 3PCE external to the host. Such a liaison system comprises: an application program interface (“API”) to receive the first code arrangement (mentioned above); and a copy command generator to generate the second code arrangement representing the third party copy command and its corresponding parameters.