Write procedure using estimated best setting in first run

• US 9,927,982 B2
• Filed: 08/18/2017
• Issued: 03/27/2018
• Est. Priority Date: 04/17/2012
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Karp, James M., Katagiri, Takashi, Mori, Yuhko, Oishi, Yutaka
• Primary Examiner(s): Yi, David X
• Assistant Examiner(s): RANKIN, CANDICE A
• Application Number:
  US15/681,160
• Publication Number:
  US 20170344272A1
• Time in Patent Office: 221 Days
• CPC Class Codes: G06F 3/0608 Saving storage space on storage systems
• CPC Class Codes: G06F 3/0653 Monitoring storage devices or systems
• CPC Class Codes: G06F 3/0659 Command handling arrangements, e.g. command buffers, queues, command scheduling
• CPC Class Codes: G06F 3/0682 Tape device
• CPC Class Codes: G11B 2220/90 Tape-like record carriers
• CPC Class Codes: G11B 5/00813 magnetic tapes
• CPC Class Codes: G11B 5/00817 on longitudinal tracks only, e.g. for serpentine format recording

Abstract

A computer program product includes a computer readable storage medium having program instructions executable by a tape drive to cause the tape drive to perform a method comprising: receiving, at the tape drive, a request for a write operation to be performed in the tape drive; determining, by the tape drive, an expected transaction size of a next write operation; comparing, by the tape drive, the expected transaction size of the next write operation to each of a first transaction size threshold and a second transaction size threshold in response to receiving the request; determining, by the tape drive, an optimum a write procedure based at least in part on the comparison; and invoking, by the tape drive, the optimum write procedure in response to determining the optimum write procedure.

Claims

1. A computer program product for implementing write procedures using an estimated best setting in a first run, the computer program product comprising a computer readable storage medium having program instructions executable by a tape drive to cause the tape drive to perform a method comprising:

receiving, at the tape drive, a request for a write operation to be performed in the tape drive;

determining, by the tape drive, an expected transaction size of a next write operation;

comparing, by the tape drive, the expected transaction size of the next write operation to each of a first transaction size threshold and a second transaction size threshold in response to receiving the request;

determining, by the tape drive, an optimum a write procedure based at least in part on the comparison; and

invoking, by the tape drive, the optimum write procedure in response to determining the optimum write procedure,

wherein the first transaction size threshold is greater than the second transaction size threshold, and

wherein the optimum write procedure is one of a plurality of candidate write procedures selected from;

a backhitch write procedure, a same wrap backhitchless flush (SWBF) write procedure, and a recursively accumulating backhitchless flush (RABF) write procedure.

2. The computer program product as recited in claim 1, wherein determining the optimum write procedure comprises:

determining a capacity margin ratio;

calculating an expected writing time for each of the backhitch write procedure, the SWBF write procedure, and the RABF write procedure;

determining an expected time remaining until the next write operation; and

selecting the optimum write procedure based on at least one of;

the expected writing time of the next write operation using the backhitch write procedure, the expected writing time of the next write operation using the SWBF write procedure, the expected writing time of the next write operation using the RABF write procedure, the expected transaction size of the next write operation, the capacity margin ratio, and the expected time remaining until the next write operation.

3. The computer program product as recited in claim 2, wherein the SWBF write procedure is selected as the optimum write procedure when:

the expected transaction size of the next write operation is greater than the first transaction size threshold;

the expected writing time of the next write operation using SWBF is less than the expected writing time of the next write operation using backhitch;

the expected time remaining until the next write operation is less than the expected writing time of the next write operation using SWBF; and

the capacity margin ratio is greater than a predetermined value.

4. The computer program product as recited in claim 2, wherein the SWBF write procedure is selected as the optimum write procedure in response to the following conditions being satisfied:

the expected transaction size of the next write operation is less than the first transaction size threshold and greater than the second transaction size threshold;

the expected time remaining until the next write operation is less than the expected writing time of the next write operation using SWBF; and

the capacity margin ratio is greater than a predetermined value.

5. The computer program product as recited in claim 2, wherein the RABF write procedure is selected as the optimum write procedure in response to the following conditions being satisfied:

the expected transaction size of the next write operation is less than the first transaction size threshold and greater than the second transaction size threshold; and

the capacity margin ratio is less than a predetermined value.

6. The computer program product as recited in claim 2, wherein the RABF write procedure is selected as the optimum write procedure in response to the following conditions being satisfied:

the expected transaction size of the next write operation is less than the first transaction size threshold and greater than the second transaction size threshold;

the expected time remaining until the next write operation is greater than the expected writing time of the next write operation using SWBF; and

the capacity margin ratio is greater than a predetermined value.

7. The computer program product as recited in claim 2, wherein the backhitch write procedure is selected as the optimum write procedure in response to the following conditions being satisfied:

the expected transaction size of the next write operation is greater than the first transaction size threshold;

the expected writing time of the next write operation using SWBF is greater than the expected writing time of the next write operation using backhitch; and

the capacity margin ratio is greater than a predetermined value.

8. The computer program product as recited in claim 2, wherein the backhitch write procedure is selected as the optimum write procedure in response to the following conditions being satisfied:

the expected transaction size of the next write operation is greater than the first transaction size threshold;

the expected writing time of the next write operation using SWBF is less than the expected writing time of the next write operation using backhitch;

the capacity margin ratio is greater than as predetermined value; and

the expected time remaining until the next write operation is greater than the expected writing time of the next write operation using SWBF.

9. The computer program product as recited in claim 2, wherein the capacity margin ratio is characterized by a value in a range from 0% to 100%, and

wherein invoking the optimum write procedure maintains the value of the capacity margin ratio below about 10%.

10. The computer program product as recited in claim 2, wherein the capacity margin ratio is a ratio between a capacity margin of the tape drive and an actual data capacity of the tape drive.

11. The computer program product as recited in claim 10, wherein the capacity margin is a difference between an actual data capacity of the tape drive and an ideal data capacity of the tape drive.

12. The computer program product as recited in claim 1, wherein at least one of the first transaction size threshold and the second transaction size threshold is based on one or more factors selected from:

a drive type corresponding to the tape drive;

a media type corresponding to the tape drive;

a user-defined value; and

a predefined value programmed into the tape drive.

13. The computer program product as recited in claim 1, wherein the expected transaction size of the next write operation comprises an average of at least two immediately previous transaction sizes.

14. The computer program product as recited in claim 1, wherein the optimum write procedure is characterized by a minimum tape drive storage capacity degradation, and

wherein each other of the candidate write procedures is characterized by a tape drive storage capacity degradation greater than the minimum tape drive storage capacity degradation.

15. The computer program product as recited in claim 1, wherein the optimum write procedure is characterized by a maximum data usage efficiency, and

wherein each other of the candidate write procedures is characterized by a data usage efficiency less than the maximum data usage efficiency.

16. The computer program product as recited in claim 1, wherein the optimum write procedure is characterized by a maximum write operation speed, and

wherein each other of the candidate write procedures is characterized by a write operation speed less than the maximum write operation speed.

17. The computer program product as recited in claim 1, wherein the optimum write procedure is characterized by at least two of:

a maximum data usage efficiency;

a maximum write operation speed; and

a minimum tape drive storage capacity degradation, and

wherein each other candidate write procedure is characterized by at least two of;

a data usage efficiency less than the maximum data usage efficiency,

a write operation speed less than the maximum write operation speed; and

a tape drive storage capacity degradation greater than the minimum tape drive storage capacity degradation.

18. The computer program product as recited in claim 17, wherein determining the optimum write procedure comprises:

determining, by the tape drive, a capacity margin ratio;

calculating, by the tape drive, an expected writing time for each of the backhitch write procedure, the SWBF write procedure, and the RABF write procedure;

determining, by the tape drive, an expected time remaining until the next write operation; and

selecting, by the tape drive, the optimum write procedure based on at least one of;

the backhitch write procedure expected writing time, the SWBF write procedure expected writing time, the RABF write procedure expected writing time, the expected transaction size of the next write operation, the capacity margin ratio, and the expected time remaining until the next write operation,

wherein the capacity margin ratio is a ratio between a capacity margin of the tape drive and an actual data capacity of the tape drive,

wherein the capacity margin is a difference between an actual data capacity of the tape drive and an ideal data capacity of the tape drive,

wherein the capacity margin ratio is characterized by a value in a range from 0% to 100%,

wherein invoking the optimum write procedure maintains the value of the capacity margin ratio below about 10%,

wherein at least one of the first transaction size threshold and the second transaction size threshold is based on one or more factors selected from;

a drive type corresponding to the tape drive;

a media type corresponding to the tape drive;

a user-defined value; and

a predefined value programmed into the tape drive, and

wherein the expected transaction size of the next write operation comprises an average of at least two immediately previous transaction sizes.

19. A computer program product for implementing write procedures using an estimated best setting in a first run, the computer program product comprising a computer readable storage medium having program instructions executable by a tape drive to cause the tape drive to perform a method, comprising:

receiving, at the tape drive, a request for a write operation to be performed in the tape drive;

determining, by the tape drive, an optimum a write procedure from among a plurality of candidate write procedures, the plurality of candidate write procedures comprising;

a backhitch (BH) write procedure,

a same wrap backhitchless flush (SWBF) write procedure, and

a recursively accumulating backhitchless flush (RABF) write procedure; and

invoking, by the tape drive, the determined optimum write procedure in response to determining the optimum write procedure,

wherein the determining is based at least in part on;

an expected writing time for each of the plurality of candidate write procedures;

an expected time remaining until a next write operation; and

an expected transaction size of the next write operation.

20. A computer program product for implementing write procedures using an estimated best setting in a first run, the computer program product comprising a computer readable storage medium having program instructions executable by a tape drive to cause the tape drive to perform a method comprising:

receiving, at the tape drive, a request for a write operation to be performed in the tape drive;

determining, by the tape drive, an optimum a write procedure in response to receiving the request, the determining comprising;

determining a capacity margin ratio;

determining an expected transaction size of a next write operation;

calculating an expected writing time for each of a backhitch write procedure, a same wrap backhitchless flush (SWBF) write procedure, and a recursively accumulating backhitchless flush (RABF) write procedure;

determining an expected time remaining until the next write operation; and

selecting the optimum write procedure based on at least one of;

the backhitch write procedure expected writing time, the SWBF write procedure expected writing time, the RABF write procedure expected writing time, the expected transaction size of the next write operation, the capacity margin ratio, and the expected time remaining until the next write operation; and

invoking the optimum write procedure based on the selection,

wherein the SWBF write procedure is selected as the optimum write procedure in response to one of the following sets of conditions being satisfied;

the expected transaction size of the next write operation is greater than a first transaction size threshold, the SWBF write procedure expected writing time is less than the backhitch write procedure expected writing time, the expected time remaining until the next write operation is less than the SWBF write procedure expected writing time and the capacity margin ratio is greater than about 7.0%; and

the expected transaction size of the next write operation is less than the first transaction size threshold and greater than a second transaction size threshold, the SWBF write procedure expected writing time is less than the backhitch write procedure expected writing time, the expected time remaining until the next write operation is less than the SWBF write procedure expected writing time and the capacity margin ratio is greater than about 7.0%,

wherein the RABF write procedure is selected as the optimum write procedure in response to one of the following conditions being satisfied;

the expected transaction size of the next write operation is less than the second transaction size threshold;

the expected transaction size of the next write operation is less than the first transaction size threshold and greater than the second transaction size threshold and the capacity margin ratio is less than about 7.0%; and

the expected transaction size of the next write operation is less than the first transaction size threshold and greater than the second transaction size threshold, the expected time remaining until the next write operation is greater than the SWBF write procedure expected writing time and the capacity margin ratio is greater than about 7.0%, and

wherein the backhitch write procedure is selected as the optimum write procedure in response to one of the following conditions being satisfied;

the expected transaction size of the next write operation is greater than the first transaction size threshold and the capacity margin ratio is less than about 7.0%;

the expected transaction size of the next write operation is greater than the first transaction size threshold, the SWBF expected writing time of the next write operation is greater than the backhitch write procedure expected writing time and the capacity margin ratio is greater than about 7.0%; and

the expected transaction size of the next write operation is greater than the first transaction size threshold, the SWBF expected writing time of the next write operation is less than the backhitch write procedure expected writing time, the capacity margin ratio is greater than about 7.0% and the expected time remaining until the next write operation is greater than the SWBF write procedure expected writing time.