Reading order search method and program for recording groups on tape

Patent metadata

Field	Value
Publication number	US-9263064-B2
Application number	US-201414176291-A
Country	US
Kind code	B2
Filing date	Feb 10, 2014
Priority date	Mar 14, 2013
Publication date	Feb 16, 2016
Grant date	Feb 16, 2016

Abstract

The present invention provides a search method used to search for the reading order of a plurality of recording groups when the plurality of recording groups written on tape are continuously read by a tape drive which manages data on tape in recording units having a fixed data length for each recording. This search method includes the steps of: receiving information on a plurality of tape groups to be read; and sorting the plurality of recording groups to be read so the reading time is shortened. In the sorting step, the time required to sort the plurality of reading groups is reduced by combining two or more recording groups into a single object to be sorted in the sorting step when at least two or more contiguous recording groups have been assigned to the same region or are assigned across adjacent regions among the plurality of regions.

First claim

The invention claimed is:

1. A method for searching a reading order of a plurality of recording groups when the plurality of recording groups written on a tape are continuously read by a tape drive which manages data on the tape in recording units having a fixed data length for each recording, the method comprising the steps of:
receiving information on a plurality of recording groups to be read, each of the plurality of recording groups having at least one recording, a recording number at a beginning and a recording number at an end of each recording group being managed by the tape drive, a predetermined number of regions being established in a longitudinal direction of each wrap of the tape, the predetermined number of regions making up a plurality of regions, and at least one recording group being assigned to each of the predetermined number of regions; and
sorting the plurality of recording groups to be read so a reading time thereof is shortened,
wherein a time required to sort the plurality of recording groups is reduced by combining two or more recording groups into a single object to be sorted in the sorting step when at least two or more contiguous recording groups have been assigned to the same region or across adjacent regions among the plurality of regions;
wherein the step of sorting the plurality of recording groups further comprises the steps of:
assigning consecutive numbers to each of the plurality of recording groups in ascending order from a beginning of each recording group and sorting the recording groups, and
continuously searching for a next recording group to be read after one recording group has been read; and

the searching step includes selecting the next recording group so that a travel time of a reading head to a start position of the next recording group inside a region of the plurality of regions assigned to the next recording group is minimized, a smallest recording number among two or more combined recording groups being a first recording number of the combined recording group when two or more recording groups have been combined, and a largest recording number being a final recording number in the combined recording groups.

2. The method according to claim 1 , wherein:
the step of sorting the plurality of recording groups includes the step of searching for a final recording group to be inserted after another recording group in a sequence of recording groups not in a final position, the searching for the final recording group performed on the basis of whether or not an overall reading time for the plurality of recording groups is shortened; and
the searching step includes combining the final recording group with at least one previous recording group, and inserting the two or more combined recording groups after another uncombined recording group on the basis of whether or not the overall reading time for the plurality of recording groups is shorter.

3. The method according to claim 1 , wherein:
the tape drive is communicatively connected to a host in a file system or virtual tape server (VTS), and
the method further includes:
sending the information on the plurality of recording groups to be read from the host to the tape drive, and
in the sorting step, sending the sorted plurality of recording groups from the tape drive to the host.

4. A system for searching a reading order of a plurality of recording groups when the plurality of recording groups written on a tape are continuously read by a tape drive which manages data on the tape in recording units having a fixed data length for each recording, system comprising:
a memory; and
a processing device coupled to the memory, the processing device:
receiving information on a plurality of recording groups to be read, each of the plurality of recording groups having at least one recording, a recording number at a beginning and a recording number at an end of each recording group being managed by the tape drive, a predetermined number of regions being established in a longitudinal direction of each wrap of the tape, the predetermined number of regions making up a plurality of regions, and at least one recording group being assigned to each of the predetermined number of regions; and
sorting the plurality of recording groups to be read so a reading time thereof is shortened,
wherein a time required to sort the plurality of recording groups is reduced by combining two or more recording groups into a single object to be sorted in the sorting step when at least two or more contiguous recording groups have been assigned to the same region or across adjacent regions among the plurality of regions;
the step of sorting the plurality of recording groups further comprises the steps of:
assigning consecutive numbers to each of the plurality of recording groups in ascending order from a beginning of each recording group and sorting the recording groups, and
continuously searching for a next recording group to be read after one recording group has been read; and

the searching step includes selecting the next recording group so that a travel time of a reading head to a start position of the next recording group inside a region of the plurality of regions assigned to the next recording group is minimized, a smallest recording number among two or more combined recording groups being a first recording number of the combined recording group when two or more recording groups have been combined, and a largest recording number being a final recording number in the combined recording groups.

5. The system according to claim 4 , wherein the processing device is:
during the sorting the plurality of recording groups, searching for a final recording group to be inserted after another recording group in a sequence of recording groups not in a final position; the searching for the final recording group performed on the basis of whether or not an overall reading time for the plurality of recording groups is shortened; and
for the searching, combining the final recording group with at least one previous recording group, and inserting the two or more combined recording groups after another uncombined recording group on the basis of whether or not the overall reading time for the plurality of recording groups is shorter.

6. The system according to claim 4 , wherein:
the tape drive is communicatively connected to a host in a file system or virtual tape server (VTS), and
the processor is further:
sending the information on the plurality of recording groups to be read from the host to the tape drive, and
in the sorting step, sending the sorted plurality of recording groups from the tape drive to the host.

7. A computer program product including a non-transitory computer readable medium for storing instructions for a method for searching a reading order of a plurality of recording groups when the plurality of recording groups written on a tape are continuously read by a tape drive which manages data on the tape in recording units having a fixed data length for each recording, the computer program product comprising the steps of:
computer code for receiving information on a plurality of recording groups to be read, each of the plurality of recording groups having at least one recording, a recording number at a beginning and a recording number at an end of each recording group being managed by the tape drive, a predetermined number of regions being established in a longitudinal direction of each wrap of the tape, the predetermined number of regions making up a plurality of regions, and at least one recording group being assigned to each of the predetermined number of regions; and
computer code for sorting the plurality of recording groups to be read so a reading time thereof is shortened,
wherein a time

Assignees

• IBM

Inventors

• Katagiri Takashi
• Nishida Mitsuhiro

Classifications

• G11B5/00817 Primary

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

• G06F3/0638

  Organizing or formatting or addressing of data · CPC title

• G11B20/1201

  on tapes · CPC title

• G11B20/10

  Digital recording or reproducing · CPC title

• G06F3/0682

  Tape device · CPC title