# US 5,345,575 A · Write optimized disk storage device

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- Number: US 5,345,575 A
- Document ID: US5345575A
- Status: Granted
- Kind: A
- Application number: 07/767,109
- Filed: 1991-09-26
- Granted: 1994-09-06
- Earliest claimed: 1991-09-26
- Assignees: Hewlett-Packard Company
- Inventors: Robert M. English; Alexander A. Stepanov
- Web page: https://patentgrep.com/patent/US5345575A

## CPC

- G11B 27/11: by using information not detectable on the record carrier
- G06F 3/0601: {Interfaces specially adapted for storage systems}
- G06F 3/0611: {in relation to response time}
- G06F 3/064: {Management of blocks}
- G06F 3/0676: {Magnetic disk device}
- G11B 20/10: Digital recording or reproducing
- G11B 20/1252: {for discontinuous data, e.g. digital information signals or computer program data}
- G11B 2020/1282: {in embedded servo fields}
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)

## Abstract

An indirectly accessed disk storage device comprises a rotating disk memory coupled to an intelligent disk controller. The intelligent disk controller responds to a request to store a packet of data by determining which storage location of the rotating disk memory are available and by selecting from among the available locations a location that can be accessed in a minimum amount of time relative to access time of any other available location. The intelligent disk controller makes its selection dynamically by monitoring the current position of the recording head of the rotating disk memory and by searching a record of available locations to select an optimal location. The intelligent disk controller then stores the packet of data on the rotating disk memory. By optimizing such data write operations, the indirectly accessed disk storage device also effectively optimizes data read operations. The indirectly accessed disk storage device also improves disk performance by reshuffling data stored on the rotating disk memory according to these policies during idle periods.

## Claims

### Claim 1

An apparatus for storing data comprising:
a storage medium characterized by column groupings of data storage locations, within any one of the column groupings all locations being accessible in similar amounts of time;
means for assigning a respective label grouping address to identify each of the column groupings;
means, responsive to a request to store a packet of data, for selecting one of the label grouping addressees; and
means for recording the data at a location within a column grouping identified by the selected address.

### Claim 2 (depends on 1)

An apparatus as in claim 1 wherein:
the selecting means includes means for determining which one of the column groupings is accessible in a minimum amount of time relative to access time of any other column grouping; and
the selected address identifies the column grouping accessible in the minimum amount of time.

### Claim 3 (depends on 1)

An apparatus as in claim 1 wherein:
the selecting means includes:
means for determining which locations are available for storing data; and
means for selecting from among the available locations a location that is accessible in a minimum
amount of time relative to access time of any other available location; and
the recording means is adapted for recording the data at the selected location.

### Claim 4

An apparatus for storing data comprising:
a storage medium having a plurality of data storage locations;
a head adjacent to the storage medium for accessing the locations, the head having a current head position relative to the locations;
means for monitoring the current head position;
means, responsive to the current head position and to a request to store a packet of data, tier determining which of the locations are nearest to the current head position;
means for determining which of the locations that are nearest to the current head position are available for data storage;
means for selecting an available location that is nearest to the current head position; and
means for recording the data at the selected location.

### Claim 5 (depends on 4)

An apparatus as in claim 4 wherein:
the locations of the storage medium are characterized by column groupings of the locations, within any one of the column groupings the locations being adjacent to one another and accessible in similar amounts of time; and
the means for determining which of the locations are nearest to the current head position includes a means for determining which one of the column groupings is nearest to the current head position.

### Claim 6

A method for storing data comprising:
providing a storage medium having a plurality of data storage locations and further providing a head adjacent to the storage medium for accessing the locations, the head having a current head position relative to the locations;
monitoring the current head position;
determining which of the locations are nearest to the current head position in response to the current head position and to a request to store a packet of data;
selecting one of the locations that are nearest to the current head position; and recording the data at the selected location.

### Claim 7 (depends on 6)

A method as in claim 6 wherein the selecting step includes:
determining which of the locations that are nearest to the current head position are available for data storage; and
selecting an available location that is nearest to the current head position.

### Claim 8 (depends on 6)

A method as in claim 6 wherein:
the storage medium is a disk storage device having a disk bandwidth; and
the method further includes providing a reserve of available storage locations sufficient for recording data at approximately half of the disk bandwidth.

### Claim 9 (depends on 6)

A method as in claim 6 wherein:
the storage medium is a disk storage device having a disk bandwidth; and
the method further includes providing a reserve of available storage locations sufficient for recording data at approximately the disk bandwidth.

### Claim 10

An apparatus for storing data comprising
a storage medium characterized by column groupings of data storage locations, within any one of the column groupings the locations being accessible in similar amounts of time;
means, responsive to a request to store a packet of data, for selecting one of the column groupings;
means for determining which of the locations are available for data storage;
means for selecting an available location within the selected column grouping;
means for recording the data at the selected location within the selected column grouping; and
means for providing a reserve of available storage locations within the column groupings.

### Claim 11 (depends on 10)

An apparatus as in claim 10 wherein:
the storage medium is a disk storage device having a disk bandwidth; and
the reserve is sufficient to provide data recording at approximately half of the disk bandwidth.

### Claim 12 (depends on 10)

An apparatus as in claim 10 wherein:
the storage medium is a disk storage device having a disk bandwidth; and
the reserve is sufficient to provide data recording at approximately the disk bandwidth.