Abstract: A storage system with primary mirror shadow comprises a storage array, and a controller. The controller is capable of predefining storage array volumes as a primary volume that is subsequently paired with a secondary volume, emulating a primary logical device and a plurality of secondary logical devices including a shadow logical device, tracking volumes and logical devices using a pointer, and instantaneously evoking a volume copy by a pointer exchange.

Abstract: A hybrid LUN copy operation that ultimately produces a full LUN copy, but involves a transient snapshot-copy-like intermediate stage. In one embodiment, a statically pre-allocated copy LUN is initialized with references pointing back to the primary LUN. Over time, the sectors, blocks, or other data-storage units of the primary LUN are copied to the copy LUN, so that, in the end, a full copy LUN in completed. In a second, alternative embodiment, both the primary LUN and copy LUN are READ and WRITE accessible immediately following the nearly instantaneous initialization of the copy LUN. In both embodiments, the copy LUN may be statically allocated. The immediate-full-LUN-copy operations provided by the present invention further enable rotatable copy-LUN groups, each copy LUN within a copy-LUN group representing a full, robust copy LUN.

Abstract: A hybrid LUN copy operation that ultimately produces a full LUN copy, but involves a transient snapshot-copy-like intermediate stage. In one embodiment, a statically pre-allocated copy LUN is initialized with references pointing back to the primary LUN. Over time, the sectors, blocks, or other data-storage units of the primary LUN are copied to the copy LUN, so that, in the end, a full copy LUN in completed. In a second, alternative embodiment, both the primary LUN and copy LUN are READ and WRITE accessible immediately following the nearly instantaneous initialization of the copy LUN. In both embodiments, the copy LUN may be statically allocated. The immediate-full-LUN-copy operations provided by the present invention further enable rotatable copy-LUN groups, each copy LUN within a copy-LUN group representing a full, robust copy LUN.

Abstract: A disk drive in which the radial alignment, track zero alignment, index to data timing, write current, asymmetry and threshold dropout can be electronically adjusted. A plurality of programs stored in random access memory run a plurality of adjustment procedures used to control the electronic adjustment functions of the disk drive. An alignment disk read by the disk drive provides alignment data for the radial, track zero and index to data alignment procedures. A microstepper circuit in the disk drive allows the read/write heads to be moved in discrete steps of approximately 1/126 of the track pitch for electronically adjusting the radial and track zero parameters. The index to data alignment is set by generating and storing an artifical index offset value. The write current and asymmetry adjustment procedures utilize digital to analog convertors (DACS) to vary the voltage supplied to the read/write heads. The threshold dropout procedure utilizes a DAC to control the output of a pulse detector.

Abstract: A disk drive in which the radial alignment, track zero alignment, index to data timing, write current, asymmetry and threshold dropout can be electronically adjusted. A plurality of programs stored in random access memory run a plurality of adjustment procedures used to control the electronic adjustment functions of the disk drive. An alignment disk read by the disk drive provides alignment data for the radial, track zero and index to data alignment procedures. A microstepper circuit in the disk drive allows the read/write heads to be moved in discrete steps of approximately 1/126 of the track pitch for electronically adjusting the radial and track zero parameters. The index to data alignment is set by generating and storing an artifical index offset value. The write current and asymmetry adjustment procedures utilize digital to analog convertors (DACS) to vary the voltage supplied to the read/write heads. The threshold dropout procedure utilizes a DAC to control the output of a pulse detector.

Abstract: A disk drive has a side-zero and a side-one analog and digital circuits. The disk drive may write both sides of the disk at the same time and then verify both sides at the same time. A microcontroller is connected to the side-zero and side-one digital circuits. The microcontroller receives the sensor index pulse from the index sensor and then sends a microcontroller index pulse to the side-zero and side-one digital circuits a predetermined period of time after receiving the sensor index pulse. The predetermined period of time is such that after the head is stepped to the next track and achieves a stable position, writing will begin.