International Business Machines Corporation

William W Chow

Alan A Fennema

Ronald J Kadlec

Armando Jesus Argumedo

Ian E Henderson

Davis S Fields, Jr

Matthew Joseph Anglin

Gregory John Tevis

Paul Y Hu

Donald Paul Warren, Jr

James M Showalter

Robert D Freeman

William J Rueger

Eugene B Rigby

Spencer D Roberts

Larry P Dunn

Stawomir P Kleczkowski

Robert Michael Nugent

Benjamin C Fiorino

Jorge L Lopez

Lowell E Dunn

Billy R Lakey

Thomas G Osterday

Bernard L Callender

A method and system for integrating migration level two (ML2) and backup tape processing provide for the backup, archival, and/or restoration of ML2 tape files without the use of tape mounts. In this manner, the amount of data movement required to recover from data loss is significantly reduced. Tape files may be recovered to their original status, even if the file has migrated to ML2. The status of the data is preserved after such a recovery operation. In this manner, data movement is reduced because no remigration of data is required after a recovery.

Integration of migration level two and backup tape processing using

A position servo system has a position loop and a velocity loop. The position loop controls the stop-lock condition and provides for movement control within a range about the stop-lock position. The velocity circuit is employed for movements outside of the range of the position servo circuit. When the velocity servo's loop is being used, a compare circuit compares the servo drive signal from the velocity circuit with a signal generated by the position servo loop which is tracking the velocity servo loop. When the compare circuit finds that the servo drive signals have equal amplitudes, then the velocity servo loop is disconnected from an actuator with the position servo loop then connected to the activation for completing the movement to a desired or target stop-lock position. The above-indicated servo system controls a topping or fine actuator carried on a carriage moved by a coarse actuator. The fine and coarse actuators move along the same axis and transverse to movement of any work element, such as a record storage disk. The coarse actuator is continuously slaved to the positioning of the topping or fine actuator. A relative position sensor disposed intermediate the fine and coarse actuators supplies a position error signal for enabling the coarse actuator to continuously follow the fine actuator. Feed forward signals are supplied from the fine actuator to the coarse actuator. A preferred embodiment is shown using an optical disk environment.

Positioning systems employing velocity and position control loops with

In a disk recorder, unintended radial portions of a transducer or head, herein termed 'skating', is rapidly controlled and stopped before the transducer or head can hit a crash stop. Even when a braking operation is effected in the wrong direction, the skating compensation reverses the braking operation for rapidly stopping the radial motion of a transducer. A pair of clamp circuits are electrically interposed between the servo actuator drive signal generation and a run-out compensation circuit such that the clamping operation does not alter the run-out compensation. The sequences of machine states for effecting the state accommodation are described.

Servo error controls

A track-seeking apparatus of a disk recorder employs a track-crossing sensor to produce track-crossing signals. An oscillator is slaved to the sensor for supplying substitute track-crossing pulses in the absence of the sensor providing such pulses or when the radial velocity exceeds a threshold velocity. A velocity profile means alters the oscillator frequency so that the oscillator produces track-crossing pulses in accordance with the profile.

Positioning systems including reliable track crossing detection for high

A tape support which provides several different functions in a reel-to-reel tape drive is disclosed. The tape support provides means for sensing tension in the tape, buffers or decouples the tape at the magnetic head from any perturbations arising at the take-up reel, and reliably guides the tape along the tape path. The tape travels along an arcuate surface of the tape support on an air bearing. A port in the arcuate surface senses pressure between the tape and the arcuate surface. This pressure is communicated to a transducer which provides an output representing the tension on the tape. Flanges on the ends of the tape support provide guiding of the tape over the air bearing and also provide venting of the air bearing to prevent tape vibration. A purge line expels a gaseous medium out of the sense port thereby keeping the sense port clear of contaminants.

Air bearing tape support for guiding tape and sensing tape tension

Ferrite read and write modules of a magnetic head assembly that are aligned and positioned within a nonferrite housing are clamped by a leaf spring between the walls of the housing. The leaf spring compensates for thermal mismatch between the ferrite modules and the housing, and compensates for stress fluctuation that occurs with temperature change. The clamping force of the leaf spring is precisely controlled.

Thermal compensation for magnetic head assembly

Diffusion bonding of dissimilar ceramics can be accomplished by the application of pressure only while the ceramics are at a temperature at which their expansion rates are the same. A process for manufacturing magnetic head cores is disclosed where a magnetic ferrite is diffusion bonded to a non-magnetic ceramic by heating the core pieces to the expansion rate crossover temperature and then applying the diffusion bonding pressure. The pressure is removed either before or after the bonded pieces are cooled.

Diffusion bonding of dissimilar ceramics

The temperature of a magnetic head assembly is reduced by active heat transfer accomplished by a thermoelectric cooling element positioned between and in contact with the head assembly housing and the head assembly. The housing serves as a heat sink from which thermal energy is diffused.

Thermoelectric cooling of magnetic head assemblies

A multielement magnetic head is formed with a closure section having a nonmagnetic ceramic substrate on which a thin layer of magnetic ferrite is deposited and processed. The thin ferrite layer is cut to define the separate transducing elements and data track separation. The closure section is joined to a wafer formed from a ferrite substrate and a thin film conductive coil means.

Multielement magnetic head assembly

A single track magnetic head assembly comprises a nonmagnetic base, a magnetic layer disposed on one surface of said base, a nonmagnetic top closure positioned adjacent to an upper portion of said magnetic layer, and a magnetic bridge section positioned adjacent to the lower portion of said magnetic layer and below said top closure. A prewound coil is attached to the bridge section. The base, the magnetic layer and the top closure have arched sections to allow accurate definition of the throat height, and to enable testing of magnetic and physical properties of the magnetic head during the assembly process.

Single track magnetic head assembly

A method of manufacturing a novel ferrite magnetic head assembly utilizes two ferrite pieces having extending fingers of closely similar dimensions that are joined in interleaving fashion and bonded to a ceramic substrate. The resultant assembly is sliced to provide closure sections for multi-track magnetic heads. Each closure section is joined to a ferrite wafer such that the wafer and closure section define a transducing gap therebetween.

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Tucson, AZ, United States of America

William W Chow