Controlling transportation of tape medium

• US 8,913,337 B2
• Filed: 09/28/2010
• Issued: 12/16/2014
• Est. Priority Date: 12/22/2009
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Katagiri, Takashi, Mori, Yuhko, Oishi, Yutaka
• Primary Examiner(s): Wong, K.
• Application Number:
  US13/510,608
• Publication Number:
  US 20120229931A1
• Time in Patent Office: 1,540 Days
• Field of Search: None
• US Class Current: 360/50
• CPC Class Codes: G06F 3/0613 in relation to throughput
• CPC Class Codes: G06F 3/0656 Data buffering arrangements
• CPC Class Codes: G06F 3/0682 Tape device
• CPC Class Codes: G11B 15/20 Moving record carrier backwards or forwards by finite amounts, i.e. backspacing, forward spacing
• CPC Class Codes: G11B 15/26 Driving record carriers by members acting directly or indirectly thereon G11B15/44 takes precedence; driving features inside container, see G11B23/04 and subgroups
• CPC Class Codes: G11B 15/442 Control thereof
• CPC Class Codes: G11B 15/444 reversing arrangements G11B15/442 takes precedence
• CPC Class Codes: G11B 20/10009 Improvement or modification of read or write signals
• CPC Class Codes: G11B 20/10527 Audio or video recording; Data buffering arrangements G11B20/12 - G11B20/18 take precedence
• CPC Class Codes: G11B 2020/10759 content data
• CPC Class Codes: G11B 2220/90 Tape-like record carriers
• CPC Class Codes: G11B 27/36 Monitoring, i.e. supervising the progress of recording or reproducing for digital recording G11B20/00 and s.gr.; for monitoring, testing or measuring of TV recorders of the type covered by H04N5/76 and subgroups, see H04N17/06
• CPC Class Codes: G11B 5/00813 magnetic tapes

Abstract

High performance is obtained without preventing achievement of a target read data rate.

In a controller 16 of a tape drive, a command processing unit 41 receives a synchronization command, and a buffer management unit 42 passes data in a buffer to a channel input-output unit 43. Then, upon completion of writing the data to the tape, a backhitch determination unit 44 determines whether or not to execute backhitch. If it is determined that backhitch should be skipped, the speed determination unit 46 determines a tape speed that minimizes a sum of a time required to write data without backhitch within a range where a data amount of a monitor target is to be written in order to achieve a target read data rate, and a time required to write data with backhitch within the range. Then, an operation signal output unit 49 issues an instruction to change the tape speed to the determined tape speed after execution of backhitch.

Claims

1. An apparatus of controlling transportation of a tape medium during data writing to the tape medium, comprising:

a determination unit that performs operations comprising;

determining a length of idle transport for achieving a target read data rate in reading written data from the tape medium; and

determining a speed for transporting the tape medium such that a portion of the tape medium transported without data writing due to skipping of backhitch has the determined length.

2. The apparatus according to claim 1, wherein the determination unit further performs operations comprising:

calculating a first required time and a second required time, wherein the first required time comprises a time required to write data without backhitch within a range of the tape medium where a predetermined amount of unit data is to be written, wherein the second required time comprises a time required to write data with backhitch within the range, and wherein the determined speed for transporting the tape medium is based on the first required time and the second required time.

3. The apparatus according to claim 2, wherein the determination unit calculates the first required time based on a first count number that indicates the number of times data is writable without backhitch within the range and calculates the second required time based on a second count number that indicates the number of times data needs to be written with backhitch executed in advance within the range.

4. The apparatus according to claim 3, further comprising:

a storage unit that stores time history information indicating a record of a time after writing of data to the tape medium and before writing of next data thereto and count history information indicating a record of the number of times data is written in order to write the unit data to the tape medium,

wherein the determination unit calculates the first count number based on the time history information and calculates the second count number based on the first count number and the count history information.

5. The apparatus according to claim 2, wherein the determination unit calculates the first required time based on a first time being a time required to write data without backhitch and calculates the second required time based on a second time being a time required to execute backhitch and then to write data.

6. The apparatus according to claim 5, further comprising:

a storage unit that stores time history information indicating a record of a time after writing of data to the tape medium and before writing of next data thereto and data amount history information indicating a record of a data amount written to the tape medium per writing,

wherein the determination unit calculates the first time based on the time history information and the data amount history information, and calculates the second time based on the data amount history information and a time required for backhitch that is calculated by using a predetermined value.

7. An apparatus of controlling transportation of a tape medium during data writing to the tape medium, comprising:

an acquisition unit that acquires a target read data rate in reading written data from the tape medium; and

a determination unit that determines a speed for transporting the tape medium based on a first required time and a second required time, wherein the first required time is obtained by multiplying a time required to write data without backhitch and the number of times data is writable without backhitch within a range of the tape medium where a predetermined amount of unit data is to be written in order to achieve the read data rate acquired by the acquisition unit, wherein the second required time is obtained by multiplying a time required to execute backhitch and then to write data, and the number of times data needs to be written with backhitch executed in advance within the range in order to achieve the read data rate acquired by the acquisition unit.

8. The apparatus according to claim 7, wherein

the determination unit calculates a plurality of sums one of which is a sum of the first required time and the second required time corresponding to each of a plurality of speeds of the tape medium, and determines a particular speed as the speed for transporting the tape medium in a case where the sum corresponding to the particular speed is the smallest among the plurality of sums.

9. A method of controlling transportation of a tape medium during data writing to the tape medium, comprising the steps of:

acquiring a target read data rate in reading written data from the tape medium;

determining a length of idle transport for achieving the acquired target read data rate in reading written data from the tape medium; and

determining a speed for transporting the tape medium such that a portion of the tape medium transported without data writing due to skipping of backhitch has the determined length.

11. The method of claim 9, further comprising:

calculating a first required time and a second required time, wherein the first required time comprises a time required to write data without backhitch within a range of the tape medium where a predetermined amount of unit data is to be written, wherein the second required time comprises a time required to write data with backhitch within the range, and wherein the determined speed for transporting the tape medium is based on the first required time and the second required time.

12. The method of claim 11,

wherein the calculation of the first required time is based on a first count number that indicates the number of times data is writable without backhitch within the range, and

wherein the calculating of the second required time is based on a second count number that indicates the number of times data needs to be written with backhitch executed in advance within the range.

13. The method of claim 12, further comprising:

storing time history information indicating a record of a time after writing of data to the tape medium and before writing of next data thereto and count history information indicating a record of the number of times data is written in order to write the unit data to the tape medium,

wherein the first count number is calculated based on the time history information, and

wherein the second count number is calculated based on the first count number and the count history information.

14. The method of claim 12,

wherein the first required time is calculated based on a first time comprising a time required to write data without backhitch, and

wherein the second required time is calculated based on a second time comprising a time required to execute backhitch and then to write data.

15. The method of claim 14, further comprising:

storing time history information indicating a record of a time after writing of data to the tape medium and before writing of next data thereto and data amount history information indicating a record of a data amount written to the tape medium per writing, wherein the first time is calculated based on the time history information and the data amount history information, and wherein the second time is calculated based on the data amount history information and a time required for backhitch that is calculated by using a predetermined value.

10. A computer readable medium device including a program executed to control transportation of a tape medium during data writing to the tape medium and performing operations, the operations comprising:

acquiring a target read data rate in reading written data from the tape medium;

determining a length of idle transport for achieving the acquired target read data rate in reading written data from the tape medium; and

determining a speed for transporting the tape medium such that a portion of the tape medium transported without data writing due to skipping of backhitch has the determined length.

16. The computer readable medium device of claim 10, wherein the operations further comprise:

calculating a first required time and a second required time, wherein the first required time comprises a time required to write data without backhitch within a range of the tape medium where a predetermined amount of unit data is to be written, wherein the second required time comprises a time required to write data with backhitch within the range, and wherein the determined speed for transporting the tape medium is based on the first required time and the second required time.

17. The computer readable medium device of claim 16,

wherein the calculation of the first required time is based on a first count number that indicates the number of times data is writable without backhitch within the range, and

wherein the calculating of the second required time is based on a second count number that indicates the number of times data needs to be written with backhitch executed in advance within the range.

18. The computer readable medium device of claim 17, wherein the operations further comprise:

storing time history information indicating a record of a time after writing of data to the tape medium and before writing of next data thereto and count history information indicating a record of the number of times data is written in order to write the unit data to the tape medium,

wherein the first count number is calculated based on the time history information, and

wherein the second count number is calculated based on the first count number and the count history information.

19. The computer readable medium device of claim 17,

wherein the first required time is calculated based on a first time comprising a time required to write data without backhitch, and

wherein the second required time is calculated based on a second time comprising a time required to execute backhitch and then to write data.

20. The computer readable medium device of claim 19, wherein the operations further comprise:

storing time history information indicating a record of a time after writing of data to the tape medium and before writing of next data thereto and data amount history information indicating a record of a data amount written to the tape medium per writing, wherein the first time is calculated based on the time history information and the data amount history information, and wherein the second time is calculated based on the data amount history information and a time required for backhitch that is calculated by using a predetermined value.