Abstract: In a data storage method for checksum DASD arrays, files are classified by length and/or other characteristic. Each relatively shorter file is written to an address or contiguous addresses typically on a single DASD of the array. The checksum stored on a checksum DASD is updated by reading the existing checksum, XORing that with the new data and writing the new checksum. Each relatively longer file is subdivided into portions all of the same size, and the number of equal portions is equal to the number of data DASDs where the file is to be written. The portions are interleaved in a stripe of addresses on the data DASDs, and the checksum of the portions is written to the checksum DASD. The characteristic transition length is dynamically varied in order that each interleaved file is provided with contiguous addresses matched to the file size.

Abstract: A method for starting and operating an electric motor such as the spindle motor of a disk drive assembly employs a segmented stator winding. On startup, the winding segments are connected in series in order to maximize torque. Motor speed is detected, and when a predetermined speed is reached, the segments are connected in parallel to reduce the effective number of winding turns and maintain a control voltage for motor speed control. Switching of the winding segments can be by active elements such as FETs or by passive reactive elements responding directly to motor speed. For more gradual motor torque constant control, the winding may have more than two segments.

Abstract: A dedicated servo transducer head for phase skewed position information signals in servo information tracks of a rigid magnetic disk drive unit has a width spanning up to eight servo information tracks in order to overcome problems in gain irregularity caused by abrupt phase jumps between tracks. An embodiment of the invention includes a track reading surface that varies in sensitivity across the width of the head to avoid gain loss during incremental radial movement with head edges overlying track edge fringes.

Abstract: A lubricant film for a thin-film disk is disclosed. The lubricant film comprises a monolayer of fixed lubricant bonded to the surface of the thin-film disk and a mobile lubricant in contact with the layer of fixed lubricant. The monolayer of lubricant film is applied to the thin-film in a method comprising applying a lubricant composition to the surface of a thin-film disk, then heating the thin-film disk at a sufficient temperature for a sufficient time to bond or fix a portion of the lubricant composition to the disk; to evaporate a portion of the lubricant composition from the surface of the disk; and to dispose a portion of the lubricant composition as a mobile lubricant in contact with the fixed lubricant.

Abstract: A WORM data storage medium includes primary and secondary data storage areas in which data and pointers to allocated but unwritten update areas are written. Original and updated data is written in a write sequence or chain of primary data areas separated by branched secondary data storage areas. The most recent updated data is found in a two level search of primary and then secondary data storage areas in order to save time by searching only those secondary areas where the most recent update exist.