Write procedure using estimated best setting in first run

Patent metadata

Field	Value
Publication number	US-9400604-B2
Application number	US-201514735565-A
Country	US
Kind code	B2
Filing date	Jun 10, 2015
Priority date	Apr 17, 2012
Publication date	Jul 26, 2016
Grant date	Jul 26, 2016

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.

First claim

What is claimed is:

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, a

Assignees

• IBM

Inventors

• Karp James M
• Katagiri Takashi
• Mori Yuhko
• Oishi Yutaka

Classifications

• G11B2220/90

  Tape-like record carriers · CPC title

• G11B5/00813

  magnetic tapes · CPC title

• G06F3/0608 Primary

  Saving storage space on storage systems · CPC title

• G06F3/0653

  Monitoring storage devices or systems · CPC title

• G06F3/0659

  Command handling arrangements, e.g. command buffers, queues, command scheduling · CPC title