Write procedure using estimated best setting in first run

• US 9,959,045 B2
• Filed: 04/17/2012
• Issued: 05/01/2018
• 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:
  US13/449,219
• Publication Number:
  US 20130275666A1
• Time in Patent Office: 2,205 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

In one general embodiment, a tape drive system includes: a read channel; a write channel; logic configured to receiving a request for a write operation to be performed in a tape drive; logic configured to determine an optimum a write procedure in response to receiving the request, the determining being based on expected writing times of each of a plurality of write procedures and an expected transaction size of a next write operation; and logic configured to invoke the determined optimum write procedure in response to determining the optimum write procedure.

Claims

1. A tape drive system, comprising:

a read channel;

a write channel;

logic configured to receive a request for a write operation to be performed in a tape drive;

logic configured to determine an optimum write procedure from among a plurality of candidate write procedures in response to receiving the request, 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

wherein determining the optimum write procedure is based on expected writing times of each of the plurality of candidate write procedures and an expected transaction size of a next write operation; and

logic configured to invoke the determined optimum write procedure in response to determining the optimum write procedure.

2. The tape drive system as recited in claim 1, wherein the logic configured to determine the optimum write procedure comprises:

logic configured to determine a capacity margin ratio;

logic configured to determine the expected transaction size of the next write operation;

logic configured to calculate the expected writing time for each of the plurality of candidate write procedures;

and

logic configured to determine an expected time remaining until the next write operation,

wherein the determining the optimum write procedure is further based on the expected time remaining until the next write operation.

3. The tape drive system 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 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 a predetermined value.

4. The tape drive system 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 a first transaction size threshold and greater than a second transaction size threshold;

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 a predetermined value.

5. The tape drive system as recited in claim 2, wherein the RABF write procedure is selected as the optimum write procedure in response to the transaction size of the next write operation being less than a second transaction size threshold.

6. The tape drive system 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 a first transaction size threshold and greater than a second transaction size threshold; and

the capacity margin ratio is less than a predetermined value.

7. The tape drive system 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 a first transaction size threshold and greater than a 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 a predetermined value.

8. The tape drive system 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 a first transaction size threshold;

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

the capacity margin ratio is greater than a predetermined value.

9. The tape drive system 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 a first transaction size threshold;

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

the capacity margin ratio is greater than a 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 the SWBF write procedure.

10. A data storage system, comprising:

the tape drive system as recited in claim 1;

a drive mechanism for passing a magnetic medium over a magnetic head; and

a controller electrically coupled to the magnetic head.

12. The tape drive system as recited in claim 2,

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

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

13. The tape drive system 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.

14. The tape drive system as recited in claim 13,

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.

15. The tape drive system as recited in claim 4,

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; and

a user-defined value and a predefined value programmed into the tape drive.

16. The tape drive system 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.

17. The tape drive system as recited in claim 1,

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.

18. The tape drive system as recited in claim 1,

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.

19. The tape drive system as recited in claim 1,

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.

11. A computer program product comprising non-transitory computer readable program code embodied on a computer readable storage medium, the computer readable program code comprising:

computer readable program code configured to receiving a request for a write operation to be performed in a tape drive;

computer readable program code configured to determine an expected transaction size of a next write operation;

computer readable program code configured to compare 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;

computer readable program code configured to determine an optimum write procedure based at least in part on the comparison; and

computer readable program code configured to invoke 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 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.

20. A tape drive system, comprising:

a read channel;

a write channel;

logic configured to receive a request for a write operation to be performed in a tape drive;

logic configured to determine an optimum 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

logic configured to invoke the determined optimum write procedure in response to determining the optimum write procedure; and

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.