Abstract: A magnetooptical disk recording device has a far-field detector for detecting radial position of a laser beam with respect to tracks on the disk. The far-field detector has a reference line dividing first and second photo detectors. The reference line is centered radially with respect to center lines of the tracks. The reference line is also center lengthwise to be tangentially center with respect to a tangential point on the track. The detector is adjustable both radially and tangentially. The tangential adjustment is based upon sensing two low reflective calibration marks on the disk that indicate centering the laser beam, hence the track tangent point, on the reference line. The calibration is based upon obtaining minimum noise in the detector output signal that signifies that the laser beam is centered on the length of the detector reference line. The calibration marks are in a mirror area disposed at one radial extremity of the disk.

Abstract: A magnetooptical disk recording device has a far-field detector for detecting radial position of a laser beam with respect to tracks on the disk. The far-field detector has a reference line dividing first and second photo detectors. The reference line is centered radially with respect to center lines of the tracks. The reference line is also center lengthwise to be tangentially center with respect to a tangential point on the track. The detector is adjustable both radially and tangentially. The tangential adjustment is based upon sensing two low reflective calibration marks on the disk that indicate centering the laser beam, hence the track tangent point, on the reference line. The calibration is based upon obtaining minimum noise in the detector output signal that signifies that the laser beam is centered on the length of the detector reference line. The calibration marks are in a mirror area disposed at one radial extremity of the disk.

Abstract: In a data storage system having a direct access storage device (DASD) and a cache, a cache directory has two types of directory entries. A track directory entry TDE identifies up to one DASD track of data records currently stored in cache. All records stored in a DASD track can be stored in a cache storage space allocated for the DASD track identified by the TDE. A cylinder directory entry CDE identifies a number N of records from any track in a respective cylinder of tracks. N is a positive integer less than the total number of records storable in a DASD track. From one to all of the DASD tracks in one cylinder may be identified in a CDE. The cache data storage allocation corresponding to a CDE is the same as that allocated for a TDE. Each TDE is addressed by a DASD track address of a cylinder while a CDE is addressed using a pseudo track number corresponding to a servo track in the DASD. A record cast out control for the cache includes examining the number of records destaged.

Abstract: Data storage apparatus having an array of cartridge-storing receptacles with a media device at one extremity of the array, provides cartridge input-output either at all of the receptacles or at a predetermined number of such receptacles. The media device may face the travel of an accessing mechanism such that a holder in accessing mechanism loads a cartridge onto the media device while the holder is situated at the media device. Interlock means prevent the removal of cartridges while the accessing means holder is active in an IO range of the receptacles. Moving the accessing means out of the IO range of receptacles, such as to the media device, enables manual insertion and removal of cartridges. A plurality of the cartridges are kept in respective slots of the cassettes. These cassettes are removably inserted into respective ones of the receptacles.

Abstract: A laser calibration apparatus and method first calibrates a maximum laser power level. Then lesser laser power levels are calibrated. A separate calibration pattern is used for calibrating each of the laser power levels. The calibration patterns used for the lesser laser power levels include the calibrated maximum laser power level. Such inclusion established a fixed relationship between the maximum laser power level and all of the lesser laser power levels. The calibration is performed on an optical disk, preferably of the magneto optical type. The calibrated laser power levels are then used to record pulse-width modulated signals.

Abstract: Data storage apparatus having an array of cartridge-storing receptacles with a media device at one extremity of the array, provides cartridge input-output either at all of the receptacles or at a predetermined number of such receptacles. The media device may face the travel of an accessing mechanism such that a holder in accessing mechanism loads a cartridge onto the media device while the holder is situated at the media device. Interlock means prevent the removal of cartridges while the accessing means holder is active in an IO range of the receptacles. Moving the accessing means out of the IO range of receptacles, such as to the media device, enables manual insertion and removal of cartridges. A plurality of the cartridges are kept in respective slots of the cassettes. These cassettes are removably inserted into respective ones of the receptacles.

Abstract: An optical disk recorder employs laser drive signals having diverse current or power levels. A scaling digital-analog-converter (DAC) supplies a scaled reference signal to a plurality of scaled DACs. The scaled DACs supply the diverse laser drive signals. Calibrating the scaling DAC calibrates the scaled DACs. A base array of DACs include not only the scaling DAC but a plurality of base array DACs. Such base array DACs control reading operations as well as supplying a threshold current. The threshold current is that laser drive signal current level below which laser 25 does not emit a laser beam. During writing, the CUT current is added to the laser drive currents supplied by the scaled DACs. A desired CUT current is determined by calculating a slope of the laser drive current to emission of radiation. Then the slope is extrapolated to a zero emission point below which no coherent emission of radiation occurs.

Abstract: An optical disk player reads either thin-substrate disks or thick-substrate disks. The disk players optical system is designed for reading the thin-substrate optical disks and has an effective numerical aperture. Thick-substrate optical disks having a thicker substrate than the thin-substrate optical disk result in the laser beam reading such thick-substrate optical disks having spherical aberration sufficient to prevent reliable data detection. When thick-substrate optical disks are being read, the read portion of the optical system is automatically changed to accommodate the undesired spherical aberration. The thick-substrate disk reflected laser beam is subjected to annular filtering that reduces spherical aberration sufficiently for enabling data and servo signal detection. Annular filtering is provided in an optical read path by an effective opaque or translucent disk centrally located in a pupil of the laser beam optical filter disposed in the read portion.

Abstract: A laser calibration apparatus and method first calibrates a maximum laser power level. Then lesser laser power levels are calibrated. A separate calibration pattern is used for calibrating each of the laser power levels. The calibration patterns used for the lesser laser power levels include the calibrated maximum laser power level. Such inclusion established a fixed relationship between the maximum laser power level and all of the lesser laser power levels. The calibration is performed on an optical disk, preferably of the magneto optical type. The calibrated laser power levels are then used to record pulse-width modulated signals.

Abstract: A single accessing mechanism is deployed adjacently to two optical media libraries. Each library has a plurality of record medium storage compartments arranged respectively into a one-compartment wide column. Each library has its own media drive (player or recorder). An accessing module in the accessing mechanism is movable along the column lengths. The accessing module has two transfer compartments respectively for transferring record media in respective ones of said libraries between the respective storage compartments and the respective media drives. The compartments, either in the accessing module or the library, are vertically offset. A vertical space between vertically adjacent record media enables a fetching apparatus to simultaneously enter such space in both libraries. Moving the accessing module upward or downward respectively selects the record medium to be fetched--in only one of the two libraries.

Abstract: A data storage system includes a data storage medium, such as a magnetic tape, that has a first control data storing area or drive partition that is addressable only by a peripheral drive mounting the medium and a plurality of other addressable data storing partitions for storing data. A volume table of contents may be stored in one of the addressable partitions. A tachometer measures and indicates physical locations on the storage medium. Each of the partitions have an extent on the storage medium indicated by said physical locations. The control data in the drive partition includes directories of medium control blocks, such as tape marks, defect marks and the like; directory of all addressable partitions including the physical locations at the beginning of each partitions and other medium physical and logical parameter data. A so-called mount-demount medium control block in the drive partition indicates a demount status that shows all data stored in the drive partition is valid.

Abstract: A laser read beam power level is increased with increasing radii and decreased with decreasing radii of scanning a spiral track in an optical disk. The change of read beam power level is adjusted in accordance with an established erasure profile. The erasure profile indicates beam power level at various radii at which recorded data are erased, such as in a magneto-optical disk. Read beam power level is adjusted from a pre-established minimum read beam power level (used at an inner disk radius) following the erasure profile. This action maximizes read power level without exceeding the erasure profile indicated power levels. Radial ranges are established for reading from the optical disk. Within each range, the laser beam read power level is kept constant, preferably at the desired power level at an radially inner-most portion of the respective range. Optical disks have the minimum laser read beam power level and an erasure profile recorded therein.

Abstract: In a magnetic tape drive, a magnetic head simultaneously senses plural track lateral position indicators to generate a like plurality of independently generated sensed position error signals. The sensed position error signals are combined to provide an output position error signal that drives a positioning system to position the magnetic laterally of the length of the magnetic tape. The output position error signal represents an average of the position errors indicated by the sensed position error signals. The quality of the sensed position error signal is monitored, enabling eliminating poor quality signals from the output position error signal for maintaining a quality servo control. If less than a predetermined number of sensed position error signals have acceptable quality, then recording data is prohibited. Independently of sensing servo indicia on a record member to generate the sensed position error signals, a lateral position of the multi-track head is sensed.

Abstract: In a write-once read-many (WORM) optical disk device recorded unipolar pulse signals having a high lineal recorded densities are read back using an inverted analog signal processing channel that processes the read back signal after polarity inversion of the read back signal. Some fields in each sector of an optical disk are recorded at a specific maximal mark density pattern. Read back of such fields is signal processed using non-inverted read back analog signal processing, i.e. the read back unipolar pulse signal is processed without polarity inversion. In the non-inverted read back, automatic gain control of the read signal is turned off such that amplification of the read back signal is at a constant gain. Also during non-inverted read back, low read back signal amplitude results in degating the read back output.

Abstract: Primary and secondary data processing systems are coupled via a communication system. Data storage in both systems is provided by a log structured array (LSA) system that stores data in compressed form. Each time data are updated within LSA, the updated data are stored in a data storage location different from the original data. Selected data recorded in a primary data storage of the primary system is remote dual copied to the secondary system for congruent storage in a secondary data storage, such as for disaster recovery purposes. The primary systems creates a remote copying session. Within such remote copying session, a series of "pending write update" sessions are ESTABLISHED. All data updated within each pending write update session is a consistency group of data. Within each pending write update session update data are retentively stored in both the primary and secondary systems (such as in a non-volatile cache).

Abstract: A peripheral data storage subsystem has means for responding to a MOUNT command received from a host processor to create and mount a host-processor-addressable logical data-storage volume. Such logical data-storage volume has a serial number VOLSER indicated in the MOUNT command. The logical data volume is assigned a predetermined area of a physical data volume, such area being termed a partition. The illustrated embodiment shows a tape subsystem in which the partitions are accessed by a control using a reel tachometer that identifies segments of the tape. Each partition has a number of the tape segments. Controls and methods are described for initializing the subsystem for effecting the automatic volume creation, appending data into a logical volume, how logical volumes are made to be portable, moving logical volumes amongst diverse physical media, tape formats usable for such logical volumes, data base control of the logical volumes and volume creation processing.

Abstract: In an optical disk drive, upon each power on or disk receipt, a mode control is set to non-operate, i.e., no commands can be received unless a mode setting command has been received. All other commands are rejected for preventing any access to an optical disk present in the drive until after a mode setting command has been received. When a mode set command is received after a power on or after each disk receipt, the mode control is set to operate which allows receipt and execution of legal commands. The mode setting requirement forces selection of write verify or not and to turn laser off or not after a predetermined time delay after completing a last command.

Abstract: A computer system includes a cache and a data storing system. The data storing system uses a write-once read-many (WORM) disk for storing computer data. The disk stores data in addressable so-called continuation chains. The cache stores pages of data in sets; each set being derived from but one of the continuation chains as having addressing affinity. Page replacement of the cache is in two steps. A first step selects the set having a page of data to be cast out. A least recently used (LRU) selection identifies the set. A second step in the page replacement is performed in one of two procedures. A first procedure, such as for sequentially processed data, selects the LIFO or page of data that was last stored in the cache of any pages in the LRU set. In a second procedure, such as for non-sequentially processed data, any one of a plurality of page selection procedures may be used, such as an LRU procedure for identifying the page of the selected set to be cast out of the cache.

Abstract: A host processor(s) is loosely-coupled by a plurality of data channels to a peripheral subsystem(s). The host processor(s) has a time of day clock. The peripheral subsystem(s) has a cluster(s) that performs peripheral controller functions. Each cluster has first and second clocks that respectively generate a log entry (logging) reference time and a subsystem time. The first and second clock times result in subsystem time stamps in a log that are not related to the time of day clock. For time correlating the time of day clock with the first and second clocks, a host time stamp is generated from the time of day clock. The host time stamp is sent to the subsystem via one of the data channels for entry into the log with the current time stamps of the first and second clocks as a time-correlating entry.

Abstract: An optical disk player has a controller circuit board attached to a cartridge receiver. A universal head, actuator (head carriage) and spindle motor assembly (HASA) module is attached to the receiving mechanism. The actuator carries an optical head assembly along a predetermined path contiguous with a transducer access opening of a cartridge in the receiver and radially of an optical disk in the cartridge. A leaf spring is mounted in a bottom portion of the module and extends along the predetermined path toward a disk mounting spindle. The leaf spring has an upstanding end portion between the spindle and the predetermined path. While the head carriage is disposed closely to the spindle and the receiver is in a load-unload position, a detent on the head carriage is engaged in an aperture in the spring that is adjacent the upstanding end portion.