# US 2014/0226236 A1 · Linear recording device for executing optimum writing upon receipt of series of commands including mixed read and write commands and method and program thereof

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- Number: US 2014/0226236 A1
- Document ID: US20140226236A1
- Status: Published application
- Kind: A1
- Application number: 14/126,839
- Filed: 2012-04-13
- Published: 2014-08-14
- Earliest claimed: 2011-06-24
- Assignees: International Business Machines Corporation
- Inventors: Toshiyuki Shiratori; Kohei Taguchi
- Web page: https://patentgrep.com/patent/US20140226236A1

## CPC

- G11B 20/10: Digital recording or reproducing
- G06F 3/0611: {in relation to response time}
- G06F 3/0656: {Data buffering arrangements}
- G06F 3/0682: {Tape device}
- G06F 12/0868: Data transfer between cache memory and other subsystems, e.g. storage devices or host systems
- G11B 5/00813: {magnetic tapes}
- G11B 5/00817: {on longitudinal tracks only, e.g. for serpentine format recording}
- G11B 20/10527: {Audio or video recording; Data buffering arrangements (G11B20/12 - G11B20/18 take precedence)}
- G11B 27/00: Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
- G11B 27/11: by using information not detectable on the record carrier
- G06F 2212/1012: Design facilitation
- G06F 2212/213: Tape storage
- G06F 2212/222: Non-volatile memory
- G06F 2212/253: Centralized memory
- G06F 2212/452: Instruction code
- G11B 2020/10898: {Overwriting or replacing recorded data}
- G11B 2020/10907: {using pseudo-overwriting, i.e. virtually or logically overwriting data on WORM media by remapping recorded blocks to alternate areas}
- G11B 2220/655: Memory in cassette [MIC]
- G11B 2220/90: Tape-like record carriers
- G11B 2220/93: Longitudinal format, wherein tracks are in the direction of the tape, read with a static head, e.g. DCC
- 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

A tape drive is provided, which executes an optimum writing method even when overwrite is intervened between mixed read and write operations. When an overwrite command is received while executing the mixed operations, which writes to a predetermined tape position, when a tape position to overwrite on is encountered before the append-written data ending position of the tape (tape EOD), the overwritten tape position is regarded as the append-written data ending position of the tape (tape EOD) to update the tape EOD by the overwritten tape position. When a tape position to overwrite is encountered after the append-written data ending position of the tape (tape EOD), the overwritten tape position is updated by the append-written data ending position of a non-volatile memory (non-volatile EOD). The of updating the EODs enhances the performance of the mixed read and write operations even when an overwrite command is intervening.

## Claims

### Claim at position 1

-6. (canceled)

### Claim 7

A system, comprising:
a tape device controller configured to:
couple to a read/write head configured to read data from a tape into a buffer and write data from the buffer onto the tape, wherein the tape is provided in a tape cartridge, and wherein the buffer is configured to store data related to reading and writing;
couple to a non-volatile memory, wherein the non-volatile memory is configured to store data stored in the buffer in response to a write command;
receive a series of commands, wherein each command causes movement of the tape to a tape position specified by the command, the series of commands including mixed read commands, overwrite commands, and append write commands, wherein the read commands include first, second, . . . , m-th, n-th read commands in this order, and wherein n=m+1;
read data from a specified position of the tape and store the data read from the specified position of the tape in the buffer in response to a read command; and
write data stored in the buffer starting from an appended data end position of the tape in response to an append write command.

### Claim 8 (depends on 7)

The system as recited in claim 7, wherein the tape device controller is further configured to:
upon receipt of an append write command, store the data stored in the buffer in the non-volatile memory starting from an appended data end position;
send a completion notification of the append write command when the data in the buffer is written in the non-volatile memory;
move the data temporarily stored in the non-volatile memory and then move the tape to a tape writing position where the data temporarily stored in the non-volatile memory is to be written to perform append writing on a basis of a predetermined criterion so as to minimize a moving distance by which the tape travels relative to the head when moving starting from an end position on the tape of read data for the m-th read command to a reading start position for the n-th read command after receipt of the append write command; and
upon receipt of an overwrite command of data in a predetermined position on the tape between the mixed commands in the series of commands, update the overwrite data position as an appended data end position when the tape position for overwriting the data is encountered earlier than the appended data end position of the tape, and update the overwrite data position as an appended data end position in the non-volatile memory when the tape position for overwriting the data is encountered later than the appended data end position of the tape.

### Claim 9 (depends on 8)

The system as recited in claim 8, wherein the criterion is satisfied when the data end position of the tape at which the data is to be written exists within the moving distance between the end position and the start position.

### Claim 10 (depends on 8)

The system as recited in claim 8, wherein the tape device controller is further configured to store the updated data end position into the non-volatile memory.

### Claim 11 (depends on 10)

The system as recited in claim 10, wherein the tape cartridge comprises the non-volatile memory.

### Claim 12

An append writing method for writing data in a tape recording device, the method comprising:
receiving a series of commands from a higher-level device each command moving a tape to a tape position specified by a moving command), the series of commands including mixed read, overwrite, and append write commands, wherein the read commands include first, second, . . . , m-th, n-th . . . , read commands in this order, and wherein n=m+1;
reading data from a specified position of the tape using a read/write head and storing data in a buffer in response to a read command; and
writing data stored in the buffer starting from an appended data end position of the tape in response to an append write command.

### Claim 13 (depends on 12)

The method as recited in claim 12, further comprising performing operations of position movement, reading, and writing on the tape back and forth in a longitudinal direction of the tape medium.

### Claim 14 (depends on 12)

The method as recited in claim 12, wherein the buffer is configured to temporarily store data related to reading and append writing, wherein the tape is configured to record data stored in the buffer, and wherein a read/write head is configured to read data from the tape into the buffer and write data from the buffer onto the tape.

### Claim 15 (depends on 14)

The method as recited in claim 14, further comprising:
upon receipt of the append write command, storing the data stored in the buffer in the non-volatile memory starting from an appended data end position;
sending a completion notification of the append write command to the higher-level device when the data in the buffer is written in the non-volatile memory;
moving the data temporarily stored in the non-volatile memory and then moving the tape to a tape writing position where the data temporarily stored in the non-volatile memory is to be written to perform append writing on a basis of a predetermined criterion so as to minimize a moving distance by which the tape travels relative to the head when moving from an end position on the tape of read data for the tri-th read command to a reading start position for the n-th read command after receipt of the append write command; and
when receiving an overwrite command of data in a predetermined position on the tape between the mixed commands in the series of commands, updating the overwrite data position as an appended data end position when the tape position for overwriting the data is encountered earlier than the appended data end position of the tape, and updating the overwrite data position as an appended data end position in the non-volatile memory when the tape position for overwriting the data is encountered later than the appended data end position of the tape.

### Claim 16 (depends on 15)

The method according to claim 15, wherein the criterion is satisfied when the data end position of the tape at which the data is to be written exists within the moving distance between the end position and the start position.

### Claim 17 (depends on 15)

The method according to claim 15, further comprising storing the updated data end position into the non-volatile memory.

### Claim 18 (depends on 17)

The method according to claim 17, wherein the tape cartridge comprises the non-volatile memory.

### Claim 19

A computer program product for writing data in a tape recording device, the computer program product comprising a computer readable storage medium having program code embodied therewith, the program code readable/executable by a computer to perform a method comprising:
upon receipt of an append write command, storing the data stored in a buffer in a non-volatile memory starting from an appended data end position;
sending back a completion notification of the append write command to a higher-level device when data in the buffer is written in the non-volatile memory;
moving the data temporarily stored in the non-volatile memory and then moving to a tape writing position where the data temporarily stored in the non-volatile memory is to be written to perform append writing on a basis of a predetermined criterion so as to minimize a moving distance by which a tape travels relative to a head, when moving from an end position on the tape of read data for a m-th read command to a reading start position for a subsequent n-th read command, wherein n=m÷1; and
when receiving an overwrite command of data in a predetermined position on the tape between mixed commands in a series of commands, updating an overwrite data end position as an appended data end position when the tape position for overwriting the data is encountered earlier than an appended data end position of the tape, and updating the overwrite data end position as an appended data end position in the non-volatile memory when the tape position for overwriting the data is encountered later than the appended data end position of the tape.

### Claim 20 (depends on 19)

The computer program product as recited in claim 19, wherein the criterion is satisfied when the data end position of the tape at which the data is to be written exists within the moving distance between the end position and the start position.

### Claim 21 (depends on 19)

The computer program product as recited in claim 19, wherein the method further comprises storing the updated data end position into the non-volatile memory.

### Claim 22 (depends on 21)

The computer program product as recited in claim 21, wherein the tape cartridge comprises the non-volatile memory.