Hybrid servo pattern configurations for magnetic tape

Patent metadata

Field	Value
Publication number	US-10770102-B2
Application number	US-201916418905-A
Country	US
Kind code	B2
Filing date	May 21, 2019
Priority date	Nov 9, 2017
Publication date	Sep 8, 2020
Grant date	Sep 8, 2020

Abstract

A tape drive-implemented method, according to one embodiment, includes: using information read from one or more servo bands on a magnetic tape to position a magnetic tape head relative to the magnetic tape. An array of data transducers is positioned along the magnetic tape head, the array extending perpendicular to a direction of travel of the magnetic tape. Moreover, a group of servo readers is positioned at each end of the array of data transducers. A distance between each of the immediately adjacent servo readers in each of the groups of servo readers is less than or equal to one third of a prespecified width of each of the servo bands. Furthermore, the distance between each of the servo readers in each of the groups and the prespecified width are both measured in a direction perpendicular to the direction of travel of the magnetic tape.

First claim

What is claimed is:

1. A tape drive-implemented method, comprising:
using information read by one or more servo readers from one or more servo bands on a magnetic tape to position a magnetic tape head relative to the magnetic tape,
wherein an array of data transducers is positioned along the magnetic tape head, the array extending perpendicular to a direction of travel of the magnetic tape,
wherein a group of servo readers is positioned at each end of the array of data transducers,
wherein a distance between each of the immediately adjacent servo readers in each of the groups of servo readers is less than or equal to one third of a prespecified width of each of the servo bands,
wherein the distance between each of the servo readers in each of the groups and the prespecified width are both measured in a direction perpendicular to the direction of travel of the magnetic tape.

2. A tape cartridge, comprising:
a supply reel; and
a magnetic tape having a plurality of servo bands,
wherein each of the servo bands includes a high density servo pattern and two timing based servo patterns,
wherein a longitudinal axis of each of the two timing based servo patterns is parallel to a longitudinal axis of the high density servo pattern,
wherein a combined width of the high density servo pattern and one of the two timing based servo patterns in a given servo band is less than or equal to two thirds of a prespecified width of each of the servo bands,
wherein the combined width and the prespecified width are each measured in a direction perpendicular to a longitudinal axis of the magnetic tape.

3. The tape cartridge as recited in claim 2 , wherein a width of each of the two timing based servo patterns and a width of the high density servo pattern are each less than or equal to one third of the prespecified width, wherein the width of each of the two timing based servo patterns and the width of the high density servo pattern are measured in the direction perpendicular to the longitudinal axis of the magnetic tape.

4. The tape cartridge as recited in claim 2 , wherein a width of each of the two timing based servo patterns and a width of the high density servo pattern are each less than or equal to one sixth of the prespecified width, wherein the width of each of the two timing based servo patterns and the width of the high density servo pattern are measured in the direction perpendicular to the longitudinal axis of the magnetic tape.

5. A computer program product for positioning a magnetic head, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions executable by a tape drive to cause the tape drive to perform a method comprising:
using, by the tape drive, information read by one or more servo readers from one or more servo bands on a magnetic tape to position a magnetic tape head relative to the magnetic tape,
wherein an array of data transducers is positioned along the magnetic tape head, the array extending perpendicular to a direction of travel of the magnetic tape,
wherein a group of servo readers is positioned at each end of the array of data transducers,
wherein a distance between each of the immediately adjacent servo readers in each of the groups of servo readers is less than or equal to one third of a prespecified width of each of the servo bands,
wherein the distance between each of the servo readers in each of the groups and the prespecified width are both measured in a direction perpendicular to the direction of travel of the magnetic tape.

6. The computer program product as recited in claim 5 , the program instructions executable by the tape drive to cause the tape drive to perform the method comprising:
determining, by the tape drive, a servo band configuration of the servo bands on the magnetic tape,
wherein in response to determining that each of the servo bands is of a third configuration having a high density servo pattern and a timing based servo pattern, the high density servo pattern and the timing based servo pattern each having a width measured in the direction perpendicular to the direction of travel of the magnetic tape, each of the widths being one third of the prespecified width:
using the servo readers to read the one or more of the servo bands includes:
reading information from the timing based servo pattern with a first servo reader of one of the groups of servo readers; and
reading information from the high density servo pattern with a second servo reader of the one of the groups of servo readers.

7. The computer program product as recited in claim 6 , wherein using information read from one or more servo bands on a magnetic tape to position the magnetic tape head relative to the magnetic tape includes:
determining a lateral position of the magnetic tape head relative to the magnetic tape using: the information read from the timing based servo pattern, and the information read from the high density servo pattern; and
determining a velocity of the magnetic tape using: the information read from the timing based servo pattern, and the information read from the high density servo pattern.

8. The computer program product as recited in claim 5 , the program instructions executable by the tape drive to cause the tape drive to perform the method comprising:
determining, by the tape drive, a servo band configuration of the servo bands on the magnetic tape,
wherein in response to determining that each of the servo bands is of a second configuration having two timing based servo patterns and a high density servo pattern sandwiched between the two timing based servo patterns, each of the timing based servo patterns and the high density servo pattern each having a width measured in the direction perpendicular to the direction of travel of the magnetic tape, each of the widths being one third of the prespecified width:
using the servo readers to read the one or more of the servo bands includes:
determining whether the magnetic tape is traveling in a forward direction;
reading information from a first of the two timing based servo patterns with a first servo reader of one of the groups of servo readers in response to determining that the magnetic tape is traveling in a forward direction;
reading information from the high density servo pattern with a second servo reader of the one of the groups of servo readers in response to determining that the magnetic tape is traveling in a forward direction;
reading information from a second of the two timing based servo patterns with the second servo reader of the one of the groups of servo readers in response to determining that the magnetic tape is not traveling in a forward direction; and
reading information from the high density servo pattern with the first servo reader of the one of the groups of servo readers in response to determining that the magnetic tape is not traveling in a forward direction.

9. The computer program product as recited in claim 8 , wherein using information read from one or more servo bands on a magnetic tape to position the magnetic tape head relative to the magnetic tape includes:
determining a lateral position of the magnetic tape head relative to the magnetic tape using: the information read from the first or second of the two timing based servo patterns, and the information read from the high density servo pattern; and
determining a velocity of the magnetic tape using: the information read from the first or second of the two timing based servo patterns, and the information read from the high density servo pattern.

10. The computer program product as recited in claim 5 , the program instructions executable by the tape d

Assignees

• IBM

Inventors

• Bui Nhan X
• Cherubini Giovanni
• Furrer Simeon
• Lantz Mark A
• Tsuruta Kazuhiro

Classifications

• G11B5/584 Primary

  for track following on tapes · CPC title

• G11B5/0086

  using cyclically driven heads providing segmented tracks · CPC title

• G11B5/00817

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

• G11B5/4813

  Mounting or aligning of arm assemblies, e.g. actuator arm supported by bearings, multiple arm assemblies, arm stacks or multiple heads on single arm (G11B5/484 takes precedence) · CPC title

• G11B5/5926 Primary

  recorded in separate tracks, e.g. servo tracks · CPC title