Write procedure using estimated best setting in first run

Patent metadata

Field	Value
Publication number	US-9959045-B2
Application number	US-201213449219-A
Country	US
Kind code	B2
Filing date	Apr 17, 2012
Priority date	Apr 17, 2012
Publication date	May 1, 2018
Grant date	May 1, 2018

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.

First claim

What is claimed is:

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.

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.

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

Assignees

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

• G06F3/0608 Primary

  Saving storage space on storage systems · CPC title

• G11B5/00817 Primary

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

• G06F3/0653

  Monitoring storage devices or systems · CPC title