Write procedure using estimated best setting in first run

• US 9,400,604 B2
• Filed: 06/10/2015
• Issued: 07/26/2016
• Est. Priority Date: 04/17/2012
• Status: Expired due to Fees

• 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:
  US14/735,565
• Publication Number:
  US 20150277777A1
• Time in Patent Office: 412 Days
• US Class Current: 1/1
• 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

In one general embodiment, a method includes receiving a request for a write operation to be performed in a tape drive; determining a capacity margin ratio of the tape drive; determining an optimum a write procedure based at least in part on the capacity margin ratio; and invoking the optimum write procedure in response to determining the optimum write procedure. The optimum write procedure is selected from the group consisting of: a backhitch write procedure, a same wrap backhitchless flush (SWBF) write procedure, and a recursively accumulating backhitchless flush (RABF) write procedure. Systems and computer program products configured to perform similar techniques are also disclosed.

Claims

1. A method, comprising:

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

determining a capacity margin ratio of the tape drive;

determining an optimum a write procedure based at least in part on the capacity margin ratio, wherein determining the optimum write procedure comprises;

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

determining an expected time remaining until a 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 capacity margin ratio, and the expected time remaining until the next write operation; and

invoking the optimum write procedure in response to determining the optimum write procedure, and

wherein the optimum write procedure is selected from the group consisting of;

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

2. The method as recited in claim 1, further comprising:

determining an expected transaction size of a next write operation; and

comparing 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,

wherein the optimum write procedure is determined further based at least in part on a result of the comparing.

3. The method as recited in claim 1, wherein the SWBF write procedure is selected as the optimum write procedure in response to determining the capacity margin ratio is greater than a predetermined value.

4. The method as recited in claim 3, wherein the SWBF write procedure is selected as the optimum write procedure further in response to determining one or more of:

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

an expected time remaining until the next write operation is less than a SWBF write procedure expected writing time.

5. The method as recited in claim 1, wherein the RABF write procedure is selected as the optimum write procedure in response to determining the capacity margin ratio is less than a predetermined value.

6. The method as recited in claim 5, wherein the RABF write procedure is selected as the optimum write procedure further in response to determining one or more of:

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

an expected time remaining until the next write operation is greater than a SWBF write procedure expected writing time.

7. The method as recited in claim 1, wherein the backhitch write procedure is selected as the optimum write procedure in response to determining the capacity margin ratio is greater than a predetermined value.

8. The method as recited in claim 7, wherein the backhitch write procedure is selected as the optimum write procedure further in response to determining one or more of:

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

a SWBF expected writing time of the next write operation is less than the backhitch write procedure expected writing time; and

an expected time remaining until the next write operation is greater than the SWBF write procedure expected writing time.

9. The method as recited in claim 1, 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 method as recited in claim 1, 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 method 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 method as recited in claim 1, wherein at least one of a first transaction size threshold and a 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 method as recited in claim 1, further comprising determining an expected transaction size of a next write operation,

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

wherein determining the optimum write procedure is further based on the expected transaction size of the next write operation.

14. The method as recited in claim 1, wherein the optimum write procedure is determined from among a plurality of candidate write procedures,

wherein the optimum write procedure is characterized by a minimum tape drive storage capacity degradation, and

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

15. The method as recited in claim 1, wherein the optimum write procedure is determined from among a plurality of candidate write procedures,

wherein the optimum write procedure is characterized by a maximum data usage efficiency, and

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

16. The method as recited in claim 1, wherein the optimum write procedure is determined from among a plurality of candidate write procedures,

wherein the optimum write procedure is characterized by a maximum write operation speed, and

wherein each candidate write procedure is characterized by a write operation speed less than the maximum write operation speed.

17. The method as recited in claim 1, wherein the optimum write procedure is determined from among a plurality of candidate write procedures,

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 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. A computer program product comprising a non-transitory computer readable program medium having stored thereon computer readable program instructions configured to cause a tape storage system to perform a method comprising:

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

determining a capacity margin ratio of the tape drive;

determining an optimum a write procedure based at least in part on the capacity margin ratio; and

invoking the optimum write procedure in response to determining the optimum write procedure,

wherein the optimum write procedure is selected from the group consisting of;

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

wherein determining the optimum write procedure comprises;

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 a 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 capacity margin ratio, and the expected time remaining until the next write operation.

19. A method, comprising:

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

determining an expected transaction size of a next write operation;

comparing 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 an optimum a write procedure based at least in part on a result of the comparing; and

invoking 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,

wherein the optimum write procedure is selected from the group consisting of;

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

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 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.