Storage Technology Corporation

Robert A Brumnet

Steven C Cacka

Hossein F Sevvom

Robert E Dean

Douglas P Schaefer

John F Kitchen

A track image read/write head buffer provides a buffer memory for each read/write head in the rotating media data storage system so that a seek request from the processor can be handled as soon as the beginning of the requested data record is positioned below the associated read/write head. The data image of the entire data storage track that contains the requested data record stored on the rotating media is read from the rotating media by the read/write head and stored in the track image read/write head buffer independent of the availability of a data communication path to the processor. Thus, the read data operation need not be synchronized with the availability of a data communication path to the processor and the requested data record is retrieved from the rotating media as soon as the data record is properly positioned. In no case is the data retrieval time greater than one revolution of the rotating media. The error correction codes written on the rotating media to protect the integrity of the requested data are maintained since they are stored in the read/write head buffer along with the data record.

System for buffering track image at each read/write head in a disk drive

The address mark triggered read/write head buffer provides a buffer memory for each read/write head in the rotating media data storage system that stores the entire track of data that includes the requested data record. Thus, the address mark triggered read/write head buffer retrieves the requested data record independent of the control module so that a seek request from the processor can be handled as soon as the beginning of the next data record stored on the track is positioned below the associated read/write head. The entire track is thereby staged faster on the average than the time to retrieve the requested data record. The address mark triggered read/write head buffer includes an address mark detection circuit to identify the beginning of the data field in each data record. The address mark is a predetermined data pattern of n bits that is written on the track a predetermined distance in advance of the data field of the data record. The address mark detection circuit compares the n data bits most recently read from the track with this predetermined data pattern of n bits as stored in memory. Once a match is detected, the buffer is enabled to store the next data record written on the track and all subsequent data records on the track.

Address mark triggered read/write head buffer

The read/write head buffer provides a buffer memory for each read/write head in the rotating media data storage system to that a seek request from the processor can be handled as soon as the beginning of the requested data record is positioned below the associated read/write head. The data image stored on the rotating media is read from the rotating media by the read/write head and stored in the read/write head buffer independent of the availability of a data communication path to the processor. Thus, the read data operation need not be synchronized with the availability of a data communication path to the processor and the requested data is retrieved from the rotating media as soon as the data record is properly positioned. In no case is the data retrieval time greater than one revolution of the rotating media. The error correction codes written on the rotating media to protect the integrity of the requested data are maintained since they are stored in the read/write head buffer along with the data record. Thus, once a data communication path is established to the processor, the control module receives the track data image from the read/write head buffer and can deformat this data from the bit serial, run length limited coding with error correction characters format of this data and convert this information to eight bit parallel data that is in an input/output record format for use by the control unit.

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Robert A Brumnet