Write procedure using estimated best setting in first run

Patent metadata

Field	Value
Publication number	US-9766813-B2
Application number	US-201313761095-A
Country	US
Kind code	B2
Filing date	Feb 6, 2013
Priority date	Apr 17, 2012
Publication date	Sep 19, 2017
Grant date	Sep 19, 2017

Abstract

In one general embodiment, a method includes 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 the comparison, 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, 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.

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 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 the comparison; 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, 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.

2. The method 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 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.

3. The method 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 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 method 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 SWBF write procedure expected writing time; and
the capacity margin ratio is greater than a predetermined value.

5. The method 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 method 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 SWBF write procedure expected writing time; and
the capacity margin ratio is greater than a predetermined value.

7. The method 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 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 a predetermined value.

8. The method 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 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 as predetermined value; and
the expected time remaining until the next write operation is greater than the SWBF write procedure expected writing time.

9. A method, comprising:
receiving a request for a write operation to be performed in a tape drive;
determining 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 a 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 the 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 the 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

Assignees

• IBM

Inventors

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

Classifications

• G06F3/0659

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

• G11B2220/90

  Tape-like record carriers · CPC title

• G11B5/00813

  magnetic tapes · CPC title

• G06F3/0653

  Monitoring storage devices or systems · CPC title

• G11B5/00817 Primary

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