Hybrid servo pattern configurations for magnetic tape

Patent metadata

Field	Value
Publication number	US-9997184-B1
Application number	US-201715808648-A
Country	US
Kind code	B1
Filing date	Nov 9, 2017
Priority date	Nov 9, 2017
Publication date	Jun 12, 2018
Grant date	Jun 12, 2018

Abstract

A tape drive-implemented method, according to one embodiment, includes: determining a servo band configuration of servo bands on a magnetic tape, using servo readers on a magnetic tape head to read one or more of the servo bands based on the determined servo band configuration, and using information read from the one or more of the servo bands to position the 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 the servo readers is positioned at each end of the array of data transducers, and 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.

First claim

What is claimed is:

1. A tape drive-implemented method, comprising:
determining a servo band configuration of servo bands on a magnetic tape;
using servo readers on a magnetic tape head to read one or more of the servo bands based on the determined servo band configuration; and
using information read from the one or more of the servo bands to position the 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 the 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. The tape drive-implemented method as recited in claim 1 , 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, and

using the information read from the one or more of the servo bands 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.

3. The tape drive-implemented method as recited in claim 1 , 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, and

using the information read from the one or more of the servo bands 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.

4. The tape drive-implemented method as recited in claim 1 , wherein in response to determining that each of the servo bands are of a first configuration having a timing based servo pattern with a width measured in the direction perpendicular to the direction of travel of the magnetic tape, the width being two thirds 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

using the information read from the one or more of the servo bands 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
determining a velocity of the magnetic tape using: the information read from the timing based servo pattern.

5. The tape drive-implemented method as recited in claim 4 , comprising:
determining whether a second servo reader of the one of the groups of servo readers is oriented over the timing based servo pattern; and
in response to determining that the second servo reader of the one of the groups of servo readers is oriented over the timing based servo pattern:
using the servo readers to read the one or more of the servo bands includes:
reading information from the timing based servo pattern with the second servo reader of the one of the groups of servo readers, and

using the information read from the one or more of the servo bands 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 by the second servo reader of the one of the groups of servo readers;
determining a velocity of the magnetic tape using: the information read from the timing based servo pattern by the second servo reader of the one of the groups of servo readers;
determining a skew of the magnetic tape head relative to the magnetic tape; and
determining tape dimensional stability information corresponding to the magnetic tape.

6. The tape drive-implemented method as recited in claim 1 , wherein 32 data transducers are positioned along the magnetic tape head in the array.

7. The tape drive-implemented method as recited in claim 1 , wherein 64 data transducers are positioned along the magnetic tape head in the array.

8. The tape drive-implemented method as recited in claim 1 , wherein 128 data transducers are positioned along the magnetic tape head in the array.

9. The tape drive-implemented method as recited in claim 1 , wherein each group of servo readers includes a third servo reader, wherein a distance between each of the servo readers and an immediately adjacent one of the servo readers in the respective group of servo readers is less than or equal to one sixth of a prespecified width of each of the servo bands.

10. The tape drive-implemented method as recited in claim 9 , wherein in response to determining that each of the servo bands

Assignees

• IBM

Inventors

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

Classifications

• 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

• 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