Abstract: A method is presented to rotate a read/write head rotatable along a first axis and comprising a first assembly having a first servo element and a second servo element. The method moves a sequential information storage medium adjacent to the read/write head along a second axis, wherein the second axis is substantially orthogonal to the first axis, and determines the rotation angle for the read/write head with respect to the sequential information storage medium using the first servo element and the second servo element. The method then positions the read/write head with respect to the second axis based upon the rotation angle.

Abstract: An apparatus and method are disclosed to generate convolution encoded data. The method supplies a convolution encoder. The method receives original data and generates convolution encoded original data. The method receives revised data. The method generates an XOR data stream by Exclusive OR'ing the original data with the revised data, forms a convolution encoded XOR data stream using the convolution encoder, and Exclusive ORs the convolution encoded XOR data stream with the convolution encoded original data to generate convolution-encoded revised data.

Abstract: A method to adjust the positions of a write element and read element disposed on a read/write head comprising a first assembly independently moveable along a first axis and comprising a first servo element, a second servo element, and the write element disposed between the first servo element and the second servo element and a second assembly independently moveable along the first axis and comprising a third servo element, a fourth servo element, and the read element disposed between the third servo element and the fourth servo element. The method moves a sequential information storage medium adjacent to the read/write head along a second axis, wherein the second axis is substantially orthogonal to the first axis, and determines a dynamic skew for the sequential information storage medium with respect to the read/write head using the first servo element and the second servo element. The method then positions the first assembly with respect to the second assembly to correct for that dynamic skew angle.

Abstract: A method to align the write channel portion of a holographic data storage system. The method establishes a write threshold correlation factor, provides a reference beam, and illuminates a holographic data storage medium encoded with a write reference orientation image with the reference beam to generate a write channel alignment data beam including a projected write reference orientation image. The method projects the write channel alignment data beam onto an optical detector, and calculates a first write correlation factor using the projected write reference orientation image, a stored write reference orientation image, and the tangential matched filter. If the method determines that the first write correlation factor is greater than or equal to the write threshold correlation factor, then the method determines that the spatial write channel is properly aligned.

Abstract: A method is disclosed to store information in a holographic data storage medium. The method provides a hologram comprising an alignment pattern, and disposes that hologram into a holographic data storage medium during manufacture.

Abstract: An apparatus, system, and method are disclosed for aberration compensation. In one embodiment, a first compensation lens used in conjunction with a second compensation lens to produce a conical beam used to read from, or write to, an optical medium. An Nth order compensation equation is used to optimize aberration errors associated with accessing the optical medium. The present invention may include a displaceable focus lens positioned relative to an optical medium. The focus lens may be displaced when the conical beam's focal length is adjusted. A displacement equation is presented to determine the preferred placement of the focus lens. By compensating for aberration, read/write errors may be reduced while accessing optical media thus increasing system robustness and facilitating the use of additional layers on optical media.

Abstract: A method is disclosed to determine an optimal power level to encode information holographically. The method sets (N) evaluation power levels, displays an evaluation image on a spatial light modulator. For each value of (i), the method energizes a light source using the (i)th power level, generates the (i)th reference beam, generates the (i)th carrier beam, forms the (i)th data beam comprising the evaluation image, forms the (i)th hologram using the (i)th reference beam and the (i)th data beam, and encodes the (i)th hologram in a holographic data storage medium, where (i) is greater than or equal to 1 and less than or equal to (N).

Abstract: A method to set a communication speed in a Serial-Attached Small Computer System Interface (“SAS”)/Serial-ATA (“SATA”) distance extender apparatus comprising a plurality of supported communication speeds and a local communication speed, a fibre channel interface, a memory, a processor, and a communication bus interconnecting the SAS/SATA Interface, the Fibre Channel interface, the memory, and the processor. The method detects traffic received by the Fibre Channel interface, and determines if the traffic comprises a SAS/SATA Open Address frame. If the traffic comprises a SAS/SATA Open Address frame, the method then determines if the local communication speed matches a communication speed utilized by an interconnected remote SAS/SATA Interface. If the local communication speed matches a communication speed utilized by an interconnected remote SAS/SATA Interface, the method transmits the traffic using the local SAS/SATA Interface.

Abstract: A method to deduplicate data by receiving a data set, setting a data chunk size, selecting a first stage deduplication algorithm, and selecting a second stage deduplication algorithm, where the first stage deduplication algorithm differs from the second stage deduplication algorithm. The method selects a data chunk, where that data chunk comprises all or a portion of the data set, performs a first stage deduplication analysis of the data chunk using the first stage deduplication algorithm. If the first stage deduplication analysis indicates duplicate data, then the method performs a second state deduplication analysis of said data chunk using the second stage deduplication algorithm to verify the data as duplicate. Only if both data deduplication analysis indicate duplicate data the data chunk is replaced by a deduplication stub or reference to the identical data chunk which is already stored.

Abstract: A method to provide data storage services using one or more holographic data storage media disposed in a holographic data storage system operated by a data storage services provider, wherein the holographic data storage system comprises a light source, a spatial light modulator, and a plurality of holographic data storage media, wherein the method receives information provided by the data storage services customer, allocates a first holographic data storage medium for exclusive storage of information provided by the data storage services customer, defines an outer storage portion of the first allocated holographic data storage medium, and stores the information as one or more holograms encoded in the outer storage portion of the first holographic data storage medium.

Abstract: A method to sequentially deduplicate data, wherein the method receives a plurality of computer files, wherein each of the plurality of computer files comprises a label comprising a file name, a file type, a version number, and file size, and stores that plurality of computer files in a deduplication queue. The method then identifies a subset of the plurality of computer files, wherein each file of the subset comprises the same file name but a different version number, and wherein the subset comprises a maximum count of version numbers, and wherein the subset comprises a portion of the plurality of computer files. The method deduplicates the subset using a hash algorithm, and removes the subset from said deduplication queue.

Abstract: Provided are a method, system, and program for managing communication between a first device and a second device and performing a recovery action at the second device in response to a credit depletion notification from the first device. The second device assigns credits indicating a number of outstanding frames the first device may transmit to the second device. The second device receives a first type or second type of credit depletion notification from the first device indicating that the first device needs additional credits to transmit further frames to the second device. The second device performs one of a plurality of recovery actions depending on whether the first type or second type of credit depletion notification was received.

Abstract: A method to evaluate a holographic data storage medium, wherein the holographic data storage medium is evaluated by a manufacturer. In certain embodiments, the holographic data storage medium is evaluated by a customer prior to encoding customer information into the storage medium. In certain embodiments, the holographic data storage medium is evaluated by a customer after encoding customer information therein.

Abstract: A method is disclosed to determine an optimal optical detector orientation to decode information encoded holographically. The method supplies a matched filter, an orientation image, a holographic data storage medium encoded with the orientation image, and an optical detector comprising a moveable input screen comprising a plurality of detector elements. The method positions the input screen in a plurality of input screen orientations and calculates a correlation factor for each of the input screen orientations. The method determines an optimal optical detector orientation using the plurality of correlation factors.

Abstract: A method to store information in a holographic data storage medium, wherein the method supplies a holographic data storage medium comprising an encoded focusing hologram and one or more encoded data holograms. The method disposes the holographic data storage medium in a holographic data storage system such that a moveable imaging lens is disposed at an (i)th position. The method illuminates the encoded focusing hologram to generate an (i)th reconstructed focusing image, projects that (i)th reconstructed focusing image through the moveable imaging lens, and onto said optical detector. The method then calculates an (i)th measured focusing metric, and determines if the (i)th measured focusing metric is greater than or equal to the threshold focusing metric. If the (i)th measured focusing metric is greater than or equal to the threshold focusing metric, then the method decodes the one or more encoded data holograms.

Abstract: A method is disclosed to store information in a holographic data storage medium. The method provides a hologram comprising an alignment pattern, and disposes that hologram into a holographic data storage medium during manufacture.

Abstract: A method, system and apparatus for efficiency coupling a LTO HH tape drive device having a Serial Attached SCSI connector to a SAS-Cable. The method for coupling a LTO HH tape drive device having a Serial Attached SCSI connector to a SAS-Cable includes employing an adapter having a structure featuring an offset between the centerlines of the LTO side and the SAS-Cable side. The method also includes reducing the overmold structure of the adapter on the SAS Cable Side of the adapter to prevent interference from excess structure contained on the connector during the insertion of the SAS Cable as well as enhancing the overmold structure of the adapter on the LTO drive side of the adapter to facilitate a secure grip on the adapter.

Abstract: A method to align the write channel portion of a holographic data storage system, wherein the method establishes a write threshold correlation factor, provides a reference beam, and illuminates a holographic data storage medium encoded with a write reference orientation image with the reference beam to generate a write channel alignment data beam including a projected write reference orientation image. The method projects the write channel alignment data beam onto an optical detector, and calculates a first write correlation factor using the projected write reference orientation image, a stored write reference orientation image, and the tangential matched filter. If the method determines that the first write correlation factor is greater than or equal to the write threshold correlation factor, then the method determines that the spatial write channel is properly aligned.

Abstract: Provided are a method, storage controller, and tape drive for adjusting read heads based on misregistration calculated from servo patterns. A plurality of first read heads read a plurality of servo patterns on a storage medium. A determination is made from the read servo patterns a skew at which the first read heads are positioned with respect to the servo patterns written to the storage medium. A determination is made of an adjustment factor to eliminate the determined skew. A plurality of second read heads that read the storage medium are adjusted by the adjustment factor.

Abstract: An apparatus for controlling a wheel motor is provided. A plurality of switches is provided for controlling a direction of current through motor coils of the wheel motor. A brushless motor control circuit is connected to each of the plurality of switches. Responsive to a request to adjust one of an angular velocity and an angular acceleration of the wheel motor, the plurality of switches are activated to place the motor coils in a predetermined configuration to maximize torque or reduce a total back electromotive force (BEMF) from the motor coils.