Apparatus and method for controlling transportation of tape medium

• US 9,087,549 B2
• Filed: 10/29/2014
• Issued: 07/21/2015
• Est. Priority Date: 12/22/2009
• Status: Expired due to Fees

• 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:
  US14/526,523
• Publication Number:
  US 20150124349A1
• Time in Patent Office: 265 Days
• Field of Search: None
• US Class Current: 1/1
• 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

An apparatus, computer readable medium device, and method for controlling transportation of a tape medium. A determination is made whether to execute a backhitch operation in response to writing a data set to tape from the buffer. If not, a determination is made whether a transaction size at which data is transferred from the buffer to the tape is less than a buffer size. If so, then a determination is made of a a new speed and whether a current speed is different from the determined new speed. If so, then a backhitch is initiated.

Claims

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

a buffer;

a controller that performs operations, the operations comprising;

determining whether to execute a backhitch operation in response to writing a data set to tape from the buffer;

determining whether a transaction size at which data is transferred from the buffer to the tape is less than a buffer size in response to determining not to execute the backhitch;

determining a new speed of the tape in response to determining that the transaction size is less than the buffer size;

determining whether a current speed is different from the determined new speed; and

initiating a backhitch in response to determining that the current tape speed is different from the determined new speed.

2. The apparatus of claim 1, wherein the operations further comprise:

executing a same wrap backhitchless flush in response to the current tape speed being the same as the determined new speed.

3. The apparatus of claim 1, wherein the operations further comprise:

executing a same wrap backhitchless flush in response to the transaction size being greater than the buffer size.

4. The apparatus of claim 1, wherein the operations further comprise:

changing the tape speed to the determined new tape speed in response to completing the initiated backhitch.

5. The apparatus of claim 1, wherein the operations further comprise:

in response to receiving a next data set in the buffer, determining whether there are sufficient data sets in the buffer to start new writing to the tape;

determining whether a time interval has passed waiting for there to be sufficient data sets to start the new writing to the tape; and

initiating the backhitch in response to determining that the time interval has passed.

6. The apparatus of claim 1, wherein the operations further comprise:

in response to determining that there are sufficient data sets to start new writing before the time interval has passed, determining whether a data set interval between a current location of a tape head and a location of an end of a last written data set is less than a threshold data set interval;

starting writing the data sets in the buffer to the tape in response to determining that the data set interval is less than the threshold data interval.

7. The apparatus of claim 6, wherein the operations further comprise:

performing a backhitch operation in response to determining that the data set interval is greater than the threshold data interval.

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

determining whether to execute a backhitch operation in response to writing a data set to tape from the buffer;

determining whether a transaction size at which data is transferred from the buffer to the tape is less than a buffer size in response to determining not to execute the backhitch;

determining a new speed of the tape in response to determining that the transaction size is less than the buffer size;

determining whether a current speed is different from the determined new speed; and

initiating a backhitch in response to determining that the current tape speed is different from the determined new speed.

9. The computer readable medium device of claim 8, wherein the operations further comprise:

executing a same wrap backhitchless flush in response to the current tape speed being the same as the determined new speed.

10. The computer readable medium device of claim 8, wherein the operations further comprise:

executing a same wrap backhitchless flush in response to the transaction size being greater than the buffer size.

11. The computer readable medium device of claim 8, wherein the operations further comprise:

changing the tape speed to the determined new tape speed in response to completing the initiated backhitch.

12. The computer readable medium device of claim 8, wherein the operations further comprise:

in response to receiving a next data set in the buffer, determining whether there are sufficient data sets in the buffer to start new writing to the tape;

determining whether a time interval has passed waiting for there to be sufficient data sets to start the new writing to the tape; and

initiating the backhitch in response to determining that the time interval has passed.

13. The computer readable medium device of claim 8, wherein the operations further comprise:

in response to determining that there are sufficient data sets to start new writing before the time interval has passed, determining whether a data set interval between a current location of a tape head and a location of an end of a last written data set is less than a threshold data set interval;

starting writing the data sets in the buffer to the tape in response to determining that the data set interval is less than the threshold data interval.

14. The computer readable medium device of claim 13, wherein the operations further comprise:

performing a backhitch operation in response to determining that the data set interval is greater than the threshold data interval.

15. A method of controlling transportation of a tape medium during data writing from a buffer to the tape medium, comprising:

determining whether to execute a backhitch operation in response to writing a data set to tape from the buffer;

determining whether a transaction size at which data is transferred from the buffer to the tape is less than a buffer size in response to determining not to execute the backhitch;

determining a new speed of the tape in response to determining that the transaction size is less than the buffer size;

determining whether a current speed is different from the determined new speed; and

initiating a backhitch in response to determining that the current tape speed is different from the determined new speed.

16. The method of claim 15, further comprising:

executing a same wrap backhitchless flush in response to the current tape speed being the same as the determined new speed.

17. The method of claim 15, further comprising:

executing a same wrap backhitchless flush in response to the transaction size being greater than the buffer size.

18. The method of claim 15, further comprising:

changing the tape speed to the determined new tape speed in response to completing the initiated backhitch.

19. The method of claim 15, further comprising:

in response to receiving a next data set in the buffer, determining whether there are sufficient data sets in the buffer to start new writing to the tape;

determining whether a time interval has passed waiting for there to be sufficient data sets to start the new writing to the tape; and

initiating the backhitch in response to determining that the time interval has passed.

20. The method of claim 15, further comprising:

in response to determining that there are sufficient data sets to start new writing before the time interval has passed, determining whether a data set interval between a current location of a tape head and a location of an end of a last written data set is less than a threshold data set interval;

starting writing the data sets in the buffer to the tape in response to determining that the data set interval is less than the threshold data interval.

21. The method of claim 20, further comprising:

performing a backhitch operation in response to determining that the data set interval is greater than the threshold data interval.