SYSTEM AND METHOD FOR CONTROLLING TRAVELING OF TAPE

• US 20090296268A1
• Filed: 05/29/2009
• Published: 12/03/2009
• Est. Priority Date: 05/30/2008
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Katagiri, Takashi, Oe, Motoko
• Granted Patent: US 8,035,912 B2
• Time in Patent Office: Days
• US Class Current: 360/77.12
• CPC Class Codes: G11B 15/473 by controlling the speed of the heads
• CPC Class Codes: G11B 5/584 for track following on tapes

Abstract

A system and method for controlling the traveling of a tape is provided. The system and method include passing data in a buffer to a channel input/output unit for writing the data to a tape. Once the data is written to the tape, a determining unit determines whether or not to perform backhitchless writing. If backhitchless writing is to be performed, then a speed determining unit determines a tape speed, where the time of data transfer from a host to the buffer is less than the time of data writing from the buffer to the tape. Thereafter, an operation signal output unit instructs a motor driver to change the speed of the tape to the determined tape speed after a backhitch is performed is a speculative FM.

Claims

1. A system for controlling the traveling of a tape in a tape drive which temporarily stores data in a buffer before writing the data to the tape, the system comprising:

a determination unit for determining if second data is to be written to the tape without performing a backhitch after first data is written to the tape, the determination unit determining a state of the system before writing the first data to the tape, the second data comprising data stored adjacent to first data stored in the buffer; and

a speed adjusting unit for adjusting the speed of the tape to prevent a backhitch due to the buffer running out of data when the determination unit determines that the second data is to be written to the tape without performing a backhitch.

2. The system according to claim 1 wherein the determination unit compares an amount of second data written to the tape prior to writing first data to the tape with an amount of second data expected to be written to the tape to an area up to a position on the tape where writing the first data commenced for determining if the second data is to be written to the tape without performing a backhitch.

3. The system according to claim 1 wherein the determination unit compares a number of times second data was written to the tape without performing a backhitch prior to writing first data to the tape, with a predetermined number of times second data can be written to the tape without performing a backhitch, for determining if the second data is to be written to the tape without performing a backhitch.

4. The system according to claim 1claim 1 wherein the determination unit compares a error frequency before writing first data to the tape, with a predetermined error frequency when writing second data to the tape without a backhitch, for determining if the second data is to be written to the tape without performing a backhitch.

5. The system according to claim 1 wherein the determination unit compares a first position on the tape where writing the first data to the tape started and a second position on the tape where writing the second data to the tape without a backhitch started with a predetermined interval between the first and second positions for determining if the second data is to be written to the tape without performing a backhitch.

6. The system according to claim 1 wherein the speed adjusting unit adjusts the speed of the tape to a predetermined speed so that a time period required for storing data of a predetermined size in the buffer is less than a time period required for writing data of the predetermined size to the tape.

7. The system according to claim 1 wherein the speed adjusting unit adjusts the speed of the tape after a backhitch is performed.

8. A system for controlling the traveling of a tape in a tape drive which temporarily stores, in a buffer, data transmitted from a higher-level system, and thereafter writes the data to the tape, the system comprising:

a determination unit for determining if second data is to be written to the tape without performing a backhitch after first data is written to the tape, the determination unit determining a state of the system before writing the first data to the tape, the second data comprising data stored adjacent to first data stored in the buffer;

a first speed choosing unit choosing a first speed when the determination unit determines that the second data is to be written to the tape without performing a backhitch, the first speed being the fastest speed satisfying a condition that time required for storing, in the buffer, data of a predetermined size transmitted from the higher-level system is shorter than time required for writing, to the tape, the data of the predetermined size stored in the buffer, among a plurality of speeds prepared in advance as the speed of the tape;

a second speed choosing unit choosing a second speed that is slower than the first speed from the plurality of speeds, when the first speed chosen by the first speed choosing unit is used and a backhitch thereby occurred in any one of a last predetermined number of times of data writing; and

a change unit changing the speed of the tape to the second speed after a backhitch is performed, when the second speed chosen by the second speed choosing unit is different from the current speed of the tape.

9. A method of controlling the traveling of a tape in a tape drive which temporarily stores, in a buffer, data transmitted from a higher-level system, and thereafter writes the data to the tape, the method comprising the steps of:

determining whether or not to write second data, which is the data next to first data stored in the buffer, to the tape without performing any backhitch after the writing of the first data to the tape, on the basis of a state before the writing of the first data to the tape; and

changing the speed of the tape so that no backhitch due to the buffer running out of data can occur, when it is determined that the second data is to be written to the tape without performing any backhitch.

10. A program for causing a computer to function as a system for controlling the traveling of a tape in a tape drive which temporarily stores, in a buffer, data transmitted from a higher-level system, and thereafter writes the data to the tape, the program causing the computer to function as:

means for determining whether or not to write second data, which is the data next to first data stored in the buffer, to the tape without performing any backhitch after the writing of the first data to the tape, on the basis of a state before the writing of the first data to the tape; and

means for changing the speed of the tape so that no backhitch due to the buffer running out of data can occur, when it is determined that the second data is to be written to the tape without performing any backhitch.