Write procedure using estimated best setting in first run

Patent metadata

Field	Value
Publication number	US-9927982-B2
Application number	US-201715681160-A
Country	US
Kind code	B2
Filing date	Aug 18, 2017
Priority date	Apr 17, 2012
Publication date	Mar 27, 2018
Grant date	Mar 27, 2018

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.

First claim

What is claimed is:

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 o

Assignees

• IBM

Inventors

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

Classifications

• G11B2220/90

  Tape-like record carriers · CPC title

• G06F3/0659

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

• G11B5/00817 Primary

  on longitudinal tracks only, e.g. for serpentine format recording · CPC title

• G11B5/00813

  magnetic tapes · CPC title

• G06F3/0608 Primary

  Saving storage space on storage systems · CPC title