The present invention relates to data storage systems, and more particularly, this invention relates to tape-based data storage systems.
Magnetic tape-based systems have been widely accepted in the computer industry as a cost-effective form of data storage. In a magnetic tape drive system, a magnetic tape containing a multiplicity of laterally positioned data tracks that extend along the length of the tape is drawn across a magnetic read/write transducer, referred to as a magnetic tape head. The magnetic tape heads can record and read data along the length of the magnetic tape surface as relative movement occurs between the head and the tape.
There is a continuous need for higher data transfer rates to and from the magnetic tape. This need is greater in a reading mode, when retrieving data from the magnetic tape. The data rate may be limited by magnetic tape speed, linear density, and a number of active read channels, etc. Currently, for a bidirectional tape head, when reading in the forward or reverse direction, only the readers on one module, usually on the trailing side, are used to read the data.
A tape-based data storage system according to one embodiment comprises a head having at least two modules, each of the modules having an array of readers and writers, wherein at least some of the writers in a first of the modules are aligned with at least some of the readers in a second of the modules in a direction parallel to a direction of tape travel relative to the head, wherein at least some of the readers in the first module are offset laterally from the readers in the second module in a direction perpendicular to the direction of tape travel relative to the head, such that in a first readback mode, the readers from the first and second modules simultaneously read unique tracks on a tape.
A tape-based data storage system according to another embodiment comprises a head having at least two modules, each of the modules having an array of piggybacked readers and writers; wherein at least some of the writers in a first of the modules are aligned with at least some of the readers in a second of the modules in a direction parallel to a direction of tape travel relative to the head, wherein at least some of the writers in the second module are aligned with at least some of the readers in the first module in a direction parallel to the direction of tape travel relative to the head, wherein at least some of the readers in the first module are offset laterally from the readers in the second module in a direction perpendicular to the direction of tape travel relative to the head, such that in a first readback mode, the readers from the first and second modules simultaneously read unique tracks on a tape, wherein, during a write mode, the readers of the second module read data just written by the writers of the first module, wherein data is written to the tape both in a forward direction and in a backward direction, wherein in the first readback mode twice as many tracks are read in a single pass of the tape across the head as are written in a single pass of the tape across the head.
A tape-based data storage system according to one embodiment comprises a head having two arrays of piggybacked readers and writers; wherein at least some of the writers in a first of the arrays are aligned with at least some of the readers in a second of the arrays in a direction parallel to a direction of tape travel relative to the head, wherein at least some of the readers in the first array are offset laterally from the readers in the second array in a direction perpendicular to the direction of tape travel relative to the head, such that in a first readback mode, the readers from the first and second arrays simultaneously read unique tracks on a tape.
Other aspects and advantages of the present invention will become apparent from the following detailed description, which, when taken in conjunction with the drawings, illustrate by way of example the principles of the invention.
For a fuller understanding of the nature and advantages of the present invention, as well as the preferred mode of use, reference should be made to the following detailed description read in conjunction with the accompanying drawings.
The following description is made for the purpose of illustrating the general principles of the present invention and is not meant to limit the inventive concepts claimed herein. Further, particular features described herein can be used in combination with other described features in each of the various possible combinations and permutations. Unless otherwise specifically defined herein, all terms are to be given their broadest possible interpretation including meanings implied from the specification as well as meanings understood by those skilled in the art and/or as defined in dictionaries, treatises, etc.
The following description discloses several preferred embodiments of tape-based storage systems, as well as operation and/or component parts thereof.
In one general embodiment, described generally with respect to
In another general embodiment, described generally with respect to
In still another general embodiment, described generally with respect to
As shown, a tape supply cartridge 120 and a take-up reel 121 are provided to support a tape 122. One or more of the reels may form part of a removable cassette and are not necessarily part of the system 100. The tape drive, such as that illustrated in
Rollers 125 guide the tape 122 across the tape head 126. Such tape head 126 is in turn coupled to a controller assembly 128 via a cable 130. The controller 128 typically controls head functions such as servo following, writing, reading, etc. The cable 130 may include read/write circuits to transmit data to the head 126 to be recorded on the tape 122 and to receive data read by the head 126 from the tape 122. An actuator 132 controls position of the head 126 relative to the tape 122.
An interface may also be provided for communication between the tape drive and a host (integral or external) to send and receive the data and for controlling the operation of the tape drive and communicating the status of the tape drive to the host, all as will be understood by those of skill in the art.
By way of example,
While arrays of transducers comprising readers and writers are preferably arranged in a piggyback configuration as shown in
Several R/W pairs 311 may be present, such as 8, 16, 32 pairs, etc. The R/W pairs 311 as shown are linearly aligned in a direction generally perpendicular to a direction of tape travel thereacross. However, the pairs may also be aligned diagonally, etc. Servo readers 313 are positioned on the outside of the array of R/W pairs, the function of which is well known.
Generally, the magnetic tape medium moves in either a forward or reverse direction as indicated by arrow 318. The magnetic tape medium and head assembly 310 operate in a transducing relationship in the manner well-known in the art. The piggybacked MR head assembly 310 includes two thin-film modules 322 and 324 of generally identical construction.
Modules 322 and 324 are joined together with a space or gap present between closures 325 thereof (partially shown) to form a single physical unit to provide read-while-write capability by activating the writer of the leading module and reader of the trailing module aligned with the writer of the leading module parallel to the direction of tape travel relative thereto. When a module 322, 324 of a piggyback head 310 is constructed, layers are formed on an electrically conductive substrate 330, e.g., of AlTiC, in generally the following order for the R/W pairs 311: an insulating layer 331, a first shield 346 typically of an iron alloy such as NiFe (permalloy), CZT or Al—Fe—Si (Sendust), a sensor 340 for sensing a data track on a magnetic medium, a second shield 348 typically of a nickel-iron alloy (e.g., 80/20 Permalloy), first and second writer pole tips 356, 358, and a coil (not shown).
The first and second writer poles 356, 358 may be fabricated from high magnetic moment materials such as 45/55 NiFe. Note that these materials are provided by way of example only, and other materials may be used. Additional layers such as insulation between the shields and/or pole tips and an insulation layer surrounding the sensor may be present. Illustrative materials for the insulation include alumina and other oxides, insulative polymers, etc.
During a read operation, the magnetic tape is read either by sensor 340 or by sensor 66 in the first or second directions 362, 364. Thus, for example, the first sensor 340 does not operate when the second sensor 366 reads the tape 360 in the first direction 362. Similarly, the second sensor 366 does not operate when the first sensor 340 reads the tape 360 in the second direction 364.
As shown further, the readers 416 in the first module 402 are offset laterally from the readers 412 in the second module 404 in a direction perpendicular to the direction of tape travel 414 relative to the head, such that in a first readback mode, the readers from the first and second modules 402 and 404 simultaneously read unique tracks on a tape.
In one embodiment, during a write mode, the readers 412 of the second module 404 read data just written by the writers 410 of the first module 402. For example, as data is written to the tape by the writers 410 of the first module 402 the readers 412 of the second (trailing) module 404 may immediately read the data. In one embodiment, at least some of the writers 418 in the second module 404 may be aligned with at least some of the readers 416 in the first module 402 in a direction parallel to the direction of tape travel 414 relative to the head. As an option, some of the writers 418 in the second module 404 may be aligned with some of the writers 410 in the first module 402 in a direction parallel to the direction of tape travel 414 relative to the head.
In one embodiment, a pole (e.g. pole 420, etc.) of each writer may extend along an extent of a sensor of a reader closest thereto in a direction perpendicular to the direction of tape travel relative to the head. As an option, at least one pole 420 of a writer 410 may extend along an extent of a sensor 422 of a reader 416 closest thereto in a direction perpendicular to the direction of tape travel 414 relative to the head. In one embodiment, the pole to be extended may be the wider pole of two poles (e.g. poles 420 and 424). The narrower of the two poles remains narrow to ensure a narrow track width.
In one embodiment, the poles 420 and 424 may be constructed of a hard material (e.g., NiFe). In this case, extending the poles 420 and 424 along the width of the sensor (as shown in dashed lines in
In one exemplary embodiment, data may be written to the tape both in a forward direction and in a backward direction, as generally shown in
As an option, the data may be written such that, in the first readback mode, data signals from all of the active readers (e.g., from both modules) are combined into a single outgoing data stream. The data stream may be outgoing to a host system (e.g. computer, etc.), for example, but could also be outgoing to an onboard processor for preprocessing, data extraction, etc. Standard deconvolution techniques may be used to separate the data.
As another option, in the first readback mode, the data received from the readers of one of the modules may be stored, at least temporarily, in a buffer and processed separately from the data received from the readers of the other of the modules. In this case, the buffer may include any mechanism for storing data received from the readers, e.g., RAM, EEPROM, flash memory, rewritable memory, etc.
In yet another option, the host or controller may receive an independent data stream from each of the modules and process both concurrently.
In another option as shown in
In one embodiment, the readers 412 and 416 may be offset laterally by one track on the tape as shown in
Using this configuration, all sensors of a plurality of read/write pairs may be active and reading data. For example, sixteen readers of sixteen read/write pairs may read from thirty-two tracks simultaneously. In one embodiment, data may be written to the magnetic tape in such a way that the data from all thirty-two tracks may be easily combined. In another embodiment, the data from one set of tracks may be stored in a buffer and combined at a later time.
It should be noted that, in various embodiments, the head assembly described in the above embodiments is not limited to two individual modules. For example, in one embodiment, the head assembly may a continuous structure. Furthermore, as shown in
While various embodiments have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of a preferred embodiment should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.