Linear recording device for executing optimum writing upon receipt of series of commands including mixed read and write commands and a method for executing the same

Patent metadata

Field	Value
Publication number	US-9601141-B2
Application number	US-201514599690-A
Country	US
Kind code	B2
Filing date	Jan 19, 2015
Priority date	Dec 25, 2009
Publication date	Mar 21, 2017
Grant date	Mar 21, 2017

Abstract

A tape recording device, method, and computer program product are provided for performing operations of position movement, reading, and writing on a tape medium, and receiving a series of commands from an upper-layer device. The tape recording device includes a buffer for temporarily storing data related to the reading and an append write, a tape for recording the data stored in the buffer, a reading and writing head for reading data from the tape into the buffer and writing the data onto the tape, control means for reading data from a designated position of the tape and storing the data in the buffer, and for writing the data stored in the buffer onto the tape from a written data end position in response to an append write command, and a non-volatile memory for storing data stored in the buffer in response to an append write command.

First claim

The invention claimed is:

1. A tape recording device for performing operations of position movement back and forth in a longitudinal direction and up and down in a latitudinal direction on a tape medium, reading, and writing to the tape medium, and receiving a series of read and write commands from an upper-layer device couplable to the tape recording device, the tape recording device comprising:
a buffer for temporarily storing therein data related to a plurality of read commands and a plurality of write commands;
a tape for recording thereon the data stored in the buffer;
a reading and writing head for reading data from the tape into the buffer and writing the data from the buffer onto the tape;
a controller for reading data from a designated position of the tape and storing the data in the buffer in response to each read command and for writing the data stored in the buffer onto the tape from a written data end position thereof in response to each write command; and
a non-volatile memory for storing therein data stored in the buffer in response to each write command, wherein the controller, upon receipt of a plurality of write commands and a subsequent read/write command, performs the following:
determines a current position of the head and a first position of the head for starting a subsequent read/write command,
determines a second position for starting a first write command, a third position for finishing the first write command, and a first write direction for the first write command,
determines a fourth position for starting a second write command, a fifth position for finishing the second write command, and a second write direction for the second write command,
performs both the first write command and the second write command prior to the subsequent read/write command if the second position, the third position, fourth position, and fifth position are each located between the current position and the first position,
performs both the first write command and the second write command prior to the subsequent read/write command if the second position, the third position, and fourth position, are each located between the current position and the first position and if the first write direction and the second write direction are in a same direction,
performs the first write command prior to the subsequent read/write command if both the second position and the third position are located between the current position and the first position;
determines a travel distance between the third position and the first starting position when the second position is located between the current position and the first starting position and the third position is not located between the current position and the first starting position;
determines a ratio of the travel distance to an amount of available space when the second position is located between the current position and the first starting position and the third position is not located between the current position and the first starting position; and
performs the first write command prior to the subsequent read/write command if the ratio is greater than a threshold amount.

2. The device of claim 1 , wherein when receiving a command for rewinding or unloading a cartridge, the controller writes all the data stored in the non-volatile memory onto the tape from the written data end position if a predetermined criterion to minimize a movement distance by which the tape travels relative to the head is satisfied.

3. The device of claim 1 , wherein when the non-volatile memory is filled up, the controller writes all the data stored in the non-volatile memory onto the tape from the written data end position if a predetermined criterion to minimize a movement distance by which the tape travels relative to the head is satisfied.

4. The device of claim 1 , wherein after having returned a completion notification of the write command, the controller does not return the completion notification of the write command if a predetermined criterion to minimize a movement distance by which the tape travels relative to the head is satisfied.

5. The device of claim 1 , wherein the controller executes the writing from the non-volatile memory onto the written data end position of the tape via the buffer.

6. The device of claim 1 , wherein
as a premise of the reading and writing commands, the controller receives a moving command from the higher-layer device so that the moving to a designated position of the tape is performed, and
the head is positioned at a written data end position on the tape or a written end position in memory in response to the moving command.

7. The device of claim 1 , wherein
the write command includes a synchronization operation, and
the controller writes the data stored in the buffer onto the tape or the non-volatile memory using the synchronization operation.

8. The device of claim 1 , wherein the non-volatile memory is a flash memory having a predetermined capacity.

9. The device of claim 8 , wherein the flash memory has a capacity of 100 megabytes or more.

10. The device of claim 1 , wherein the non-volatile memory is a preparatory track area in the same tape of a cartridge.

11. A method for writing to a tape recording device, wherein the tape recording device receives a plurality of read commands and a plurality of write commands from an upper-layer device and comprises a buffer for temporarily storing data related to each read command and each write command, a tape for recording the data stored in the buffer, a reading and writing head for reading data from the tape into the buffer and for writing the data from the buffer onto the tape, and a controller for reading data from a designated position of the tape and storing the data in the buffer in response to each read command and for writing the data stored in the buffer onto the tape from each written data end position (EOD) in response to each write command, the method comprising:
receiving a plurality of write commands and a subsequent read/write command;
determining a current position of the head and a first position of the head for starting the subsequent read/write command;
determining a second position for starting a first write command, a third position for finishing the first write command, and a first write direction for the first write command;
determining a fourth position for starting a second write command, a fifth position for finishing the second write command, and a second write direction for the second write command;
performing both the first write command and the second write command prior to the subsequent read/write command if the second position, the third position, fourth position, and fifth position are each located between the current position and the first position;
performing both the first write command and the second write command prior to the subsequent read/write command if the second position, the third position, and fourth position, are each located between the current position and the first position and if the first write direction and the second write direction are in a same direction;
performing the first write command prior to the subsequent read/write command if both the second position and the third position are located between the current position and the first position;
determining a travel distance between the third position and the first starting position when the second position is located between the current position and the first starting position and the third position is not located between the current position and the first starting position;
determining a ratio of the travel distance to an amount of available space when the second pos

Assignees

• IBM

Inventors

• Shiratori Toshiyuki
• Taguchi Kohei

Classifications

• G11B5/00817 Primary

  on longitudinal tracks only, e.g. for serpentine format recording · CPC title

• G06F3/0608

  Saving storage space on storage systems · CPC title

• G11B2220/90

  Tape-like record carriers · CPC title

• G11B2020/10759

  content data · CPC title

• G11B5/584

  for track following on tapes · CPC title