Utilization of multiple writer modules for simultaneously writing two times the number of data tracks in a compact form factor

In one general embodiment, an apparatus includes a first outer module having an array of writers, a second outer module having an array of writers, an inner module positioned between the outer modules, and a first actuator for shifting the first outer module. The shifting is relative to the inner module, in a cross-track direction by about one half of a center-to-center pitch of the writers of the first outer module. The inner module has an array of readers.

BACKGROUND

The present invention relates to data storage systems, and more particularly, this invention relates to the selective shifting of modules of a magnetic recording head to enable simultaneous writing by writers of different write modules to different data tracks.

In magnetic storage systems, magnetic transducers read data from and write data onto magnetic recording media. Data is written on the magnetic recording media by moving a magnetic recording transducer to a position over the media where the data is to be stored. The magnetic recording transducer then generates a magnetic field, which encodes the data into the magnetic media. Data is read from the media by similarly positioning the magnetic read transducer and then sensing the magnetic field of the magnetic media. Read and write operations may be independently synchronized with the movement of the media to ensure that the data can be read from and written to the desired location on the media.

An important and continuing goal in the data storage industry is that of increasing the density of data stored on a medium. For tape storage systems, that goal has led to increasing the track and linear bit density on recording tape, and decreasing the thickness of the magnetic tape medium. However, the development of small footprint, higher performance tape drive systems has created various problems in the design of a tape head assembly for use in such systems.

In a tape drive system, the drive moves the magnetic tape over the surface of the tape head at high speed. Usually the tape head is designed to minimize the spacing between the head and the tape. The spacing between the magnetic head and the magnetic tape is crucial and so goals in these systems are to have the recording gaps of the transducers, which are the source of the magnetic recording flux in near contact with the tape to effect writing sharp transitions, and to have the read elements in near contact with the tape to provide effective coupling of the magnetic field from the tape to the read elements.

SUMMARY

An apparatus according to one embodiment includes a first outer module having an array of writers, a second outer module having an array of writers, an inner module positioned between the outer modules, and a first actuator for shifting the first outer module. The shifting is relative to the inner module, in a cross-track direction by about one half of a center-to-center pitch of the writers of the first outer module. The inner module has an array of readers.

An apparatus according to another embodiment includes a first outer module having an array of writers, a second outer module having an array of writers, an inner module positioned between the outer modules, and an actuator for shifting the inner module. The shifting is relative to the outer modules, for selectively aligning the readers with the writers of the outer modules depending on tape travel direction. The writers of the second outer module being offset from the writers of the first outer module in a cross-track direction by about one half of a center-to-center pitch of the writers of the second outer module, positions of the first and second outer modules being fixed relative to one another. The inner module has an array of readers.

A tape drive-implemented method may be implemented in a tape drive having at least a first outer module having an array of writers, a second outer module having an array of writers, and an inner module positioned between the outer modules, the inner module having an array of readers, according to one embodiment. The method includes shifting at least one of the modules by about one half of a center-to-center pitch of the readers of the inner module, and simultaneously writing a plurality of data tracks on a magnetic recording tape using the outer modules. The data tracks written by a trailing one of the outer modules are offset in a cross-track direction from the data tracks written by a leading one of the outer modules.

Any of these embodiments may be implemented in a magnetic data storage system such as a tape drive system, which may include a magnetic head, a drive mechanism for passing a magnetic medium (e.g., recording tape) over the magnetic head, and a controller electrically coupled to the magnetic head.

DETAILED DESCRIPTION

The following description discloses several preferred embodiments of increasing simultaneous writing capacity in a magnetic storage system, as well as operation and/or component parts thereof.

In one general embodiment, an apparatus includes a first outer module having an array of writers, a second outer module having an array of writers, an inner module positioned between the outer modules, and a first actuator for shifting the first outer module. The shifting is relative to the inner module, in a cross-track direction by about one half of a center-to-center pitch of the writers of the first outer module. The inner module has an array of readers.

In another general embodiment, an apparatus includes a first outer module having an array of writers, a second outer module having an array of writers, an inner module positioned between the outer modules, and an actuator for shifting the inner module. The shifting is relative to the outer modules, for selectively aligning the readers with the writers of the outer modules depending on tape travel direction. The writers of the second outer module being offset from the writers of the first outer module in a cross-track direction by about one half of a center-to-center pitch of the writers of the second outer module, positions of the first and second outer modules being fixed relative to one another. The inner module has an array of readers.

In yet another general embodiment, a tape drive-implemented method may be implemented in a tape drive having at least a first outer module having an array of writers, a second outer module having an array of writers, and an inner module positioned between the outer modules, the inner module having an array of readers. The method includes shifting at least one of the modules by about one half of a center-to-center pitch of the readers of the inner module, and simultaneously writing a plurality of data tracks on a magnetic recording tape using the outer modules. The data tracks written by a trailing one of the outer modules are offset in a cross-track direction from the data tracks written by a leading one of the outer modules.

FIG. 1Aillustrates a simplified tape drive100of a tape-based data storage system, which may be employed in the context of the present invention. While one specific implementation of a tape drive is shown inFIG. 1A, it should be noted that the embodiments described herein may be implemented in the context of any type of tape drive system.

As shown, a tape supply cartridge120and a take-up reel121are provided to support a tape122. One or more of the reels may form part of a removable cartridge and are not necessarily part of the system100. The tape drive, such as that illustrated inFIG. 1A, may further include drive motor(s) to drive the tape supply cartridge120and the take-up reel121to move the tape122over a tape head126of any type. Such head may include an array of readers, writers, or both.

Guides125guide the tape122across the tape head126. Such tape head126is in turn coupled to a controller128via a cable130. The controller128, may be or include a processor and/or any logic for controlling any subsystem of the drive100. For example, the controller128typically controls head functions such as servo following, data writing, data reading, etc. The controller128may include at least one servo channel and at least one data channel, each of which include data flow processing logic configured to process and/or store information to be written to and/or read from the tape122. The controller128may operate under logic known in the art, as well as any logic disclosed herein, and thus may be considered as a processor for any of the descriptions of tape drives included herein, in various embodiments. The controller128may be coupled to a memory136of any known type, which may store instructions executable by the controller128. Moreover, the controller128may be configured and/or programmable to perform or control some or all of the methodology presented herein. Thus, the controller128may be considered to be configured to perform various operations by way of logic programmed into one or more chips, modules, and/or blocks; software, firmware, and/or other instructions being available to one or more processors; etc., and combinations thereof.

The cable130may include read/write circuits to transmit data to the head126to be recorded on the tape122and to receive data read by the head126from the tape122. An actuator132controls position of the head126relative to the tape122.

An interface134may also be provided for communication between the tape drive100and a host (internal or external) to send and receive the data and for controlling the operation of the tape drive100and communicating the status of the tape drive100to the host, all as will be understood by those of skill in the art.

FIG. 1Billustrates an exemplary tape cartridge150according to one embodiment. Such tape cartridge150may be used with a system such as that shown inFIG. 1A. As shown, the tape cartridge150includes a housing152, a tape122in the housing152, and a nonvolatile memory156coupled to the housing152. In some approaches, the nonvolatile memory156may be embedded inside the housing152, as shown inFIG. 1B. In more approaches, the nonvolatile memory156may be attached to the inside or outside of the housing152without modification of the housing152. For example, the nonvolatile memory may be embedded in a self-adhesive label154. In one preferred embodiment, the nonvolatile memory156may be a Flash memory device, read-only memory (ROM) device, etc., embedded into or coupled to the inside or outside of the tape cartridge150. The nonvolatile memory is accessible by the tape drive and the tape operating software (the driver software), and/or another device.

By way of example,FIG. 2Aillustrates a side view of a flat-lapped, bi-directional, two-module magnetic tape head200which may be implemented in the context of the present invention. As shown, the head includes a pair of bases202, each equipped with a module204, and fixed at a small angle α with respect to each other. The bases may be “U-beams” that are adhesively coupled together. Each module204includes a substrate204A and a closure204B with a thin film portion, commonly referred to as a “gap” in which the readers and/or writers206are formed. In use, a tape208is moved over the modules204along a media (tape) bearing surface209in the manner shown for reading and writing data on the tape208using the readers and writers. The wrap angle θ of the tape208at edges going onto and exiting the flat media support surfaces209are usually between about 0.1 degree and about 3 degrees.

The substrates204A are typically constructed of a wear resistant material, such as a ceramic. The closures204B may be made of the same or similar ceramic as the substrates204A.

The readers and writers may be arranged in a piggyback or merged configuration. An illustrative piggybacked configuration comprises a (magnetically inductive) writer transducer on top of (or below) a (magnetically shielded) reader transducer (e.g., a magnetoresistive reader, etc.), wherein the poles of the writer and the shields of the reader are generally separated. An illustrative merged configuration comprises one reader shield in the same physical layer as one writer pole (hence, “merged”). The readers and writers may also be arranged in an interleaved configuration. Alternatively, each array of channels may be readers or writers only. Any of these arrays may contain one or more servo track readers for reading servo data on the medium.

FIG. 2Billustrates the tape bearing surface209of one of the modules204taken from Line2B ofFIG. 2A. A representative tape208is shown in dashed lines. The module204is preferably long enough to be able to support the tape as the head steps between data bands.

In this example, the tape208includes 4 to 32 data bands, e.g., with 16 data bands and 17 servo tracks210, as shown inFIG. 2Bon a one-half inch wide tape208. The data bands are defined between servo tracks210. Each data band may include a number of data tracks, for example 1024 data tracks (not shown). During read/write operations, the readers and/or writers206are positioned to specific track positions within one of the data bands. Outer readers, sometimes called servo readers, read the servo tracks210. The servo signals are in turn used to keep the readers and/or writers206aligned with a particular set of tracks during the read/write operations.

FIG. 2Cdepicts a plurality of readers and/or writers206formed in a gap218on the module204in Circle2C ofFIG. 2B. As shown, the array of readers and writers206includes, for example, 16 writers214, 16 readers216and two servo readers212, though the number of elements may vary. Illustrative embodiments include 8, 16, 32, 40, and 64 active readers and/or writers206per array, and alternatively interleaved designs having odd numbers of reader or writers such as 17, 25, 33, etc. An illustrative embodiment includes 32 readers per array and/or 32 writers per array, where the actual number of transducer elements could be greater, e.g., 33, 34, etc. This allows the tape to travel more slowly, thereby reducing speed-induced tracking and mechanical difficulties and/or execute fewer “wraps” to fill or read the tape. While the readers and writers may be arranged in a piggyback configuration as shown inFIG. 2C, the readers216and writers214may also be arranged in an interleaved configuration. Alternatively, each array of readers and/or writers206may be readers or writers only, and the arrays may contain one or more servo readers212. As noted by consideringFIGS. 2A and 2B-2Ctogether, each module204may include a complementary set of readers and/or writers206for such things as bi-directional reading and writing, read-while-write capability, backward compatibility, etc.

FIG. 2Dshows a partial tape bearing surface view of complementary modules of a magnetic tape head200according to one embodiment. In this embodiment, each module has a plurality of read/write (R/W) pairs in a piggyback configuration formed on a common substrate204A and an optional electrically insulative layer236. The writers, exemplified by the write transducer214and the readers, exemplified by the read transducer216, are aligned parallel to an intended direction of travel of a tape medium thereacross to form an R/W pair, exemplified by the R/W pair222. Note that the intended direction of tape travel is sometimes referred to herein as the direction of tape travel, and such terms may be used interchangeably. Such direction of tape travel may be inferred from the design of the system, e.g., by examining the guides; observing the actual direction of tape travel relative to the reference point; etc. Moreover, in a system operable for bi-direction reading and/or writing, the direction of tape travel in both directions is typically parallel and thus both directions may be considered equivalent to each other.

Several R/W pairs222may be present, such as 8, 16, 32 pairs, etc. The R/W pairs222as 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 readers212are 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 arrow220. The magnetic tape medium and head assembly200operate in a transducing relationship in the manner well-known in the art. The piggybacked magnetoresistive (MR) head assembly200includes two thin-film modules224and226of generally identical construction.

Modules224and226are joined together with a space present between closures204B 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 module224,226of a piggyback head200is constructed, layers are formed in the gap218created above an electrically conductive substrate204A (partially shown), e.g., of AlTiC, in generally the following order for the R/W pairs222: an insulating layer236, a first shield232typically of an iron alloy such as NiFe (—), cobalt zirconium tantalum (CZT) or Al—Fe—Si (Sendust), a sensor234for sensing a data track on a magnetic medium, a second shield238typically of a nickel-iron alloy (e.g., ˜80/20 at % NiFe, also known as permalloy), first and second writer pole tips228,230, and a coil (not shown). The sensor may be of any known type, including those based on MR, GMR, AMR, tunneling magnetoresistance (TMR), etc.

The first and second writer poles228,230may 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.

The configuration of the tape head126according to one embodiment includes multiple modules, preferably three or more. In a write-read-write (W-R-W) head, outer modules for writing flank one or more inner modules for reading.

Each of the writers of a first write module in a conventional W-R-W head are often aligned along the same data tracks as a corresponding writer of a second write module of the conventional W-R-W head. Accordingly, each of the writers of the conventional first write module would write to the same respective data tracks as the correspondingly paired writer of a second write module, if the writers of both modules were activated simultaneously. Embodiments described herein include implementing actuators in magnetic tape drives for the selective shifting of one or more modules to enable simultaneous writing by writers of different write modules to different data tracks.

FIGS. 3-5depict a system300in accordance with one embodiment. As an option, the present system300may be implemented in conjunction with features from any other embodiment listed herein, such as those described with reference to the other FIGS. Of course, however, such system300and others presented herein may be used in various applications and/or in permutations which may or may not be specifically described in the illustrative embodiments listed herein. Further, the system300presented herein may be used in any desired environment.

Referring now toFIG. 3, system300includes an apparatus318. The apparatus318may be the system300or a portion thereof.

Apparatus318includes a first outer module302having an array of writers314, and a second outer module306having an array of writers314.

Apparatus318also includes an inner module304positioned between the outer modules302,306. The inner module304may have an array of readers312.

Variations of a multi-module head include arrangements in which one or more of the modules may have read/write pairs of transducers. Moreover, more than three modules may be present. In further approaches, two outer modules may flank two or more inner modules, e.g., in a W-R-R-W, a R-W-W-R arrangement, etc. For simplicity, a W-R-W head is used primarily herein to exemplify a few of the many possible embodiments of the present invention. One skilled in the art apprised with the teachings herein will appreciate how permutations of the present description may apply to various configurations other than a W-R-W configuration.

A magnetic recording medium, e.g., a magnetic recording tape, hereafter referred to as “tape,” may be passed over each of the modules302,304,306in a first direction316. It should be noted that the tape is not illustrated inFIGS. 3-4for simplicity; however, the tape may be seen inFIG. 5, which illustrates a partial tape bearing surface view of system300.

Apparatus318includes a first actuator308for shifting the first outer module302. According to various embodiments, the first actuator308may shift the first outer module302, relative to the inner module304, in a cross-track direction, e.g., a direction about orthogonal to the first direction316. The shift may be about one half of a center-to-center pitch322of the writers314of the first outer module302when writing in a direction in which the second outer module306is the leading module. To clarify, the leading module may be the first module the tape encounters when traveling in a given direction, e.g., the second outer module306is the leading module inFIG. 3(with respect to tape traveling in the first direction316).

Although the first outer module302is shifted about one half of a center-to-center pitch322of the writers314of the first outer module302in the present embodiment, according to other embodiments, the first actuator308may shift the first outer module302to some other position whereby the writers314of the first outer module302write data tracks320in a different location than the data tracks320that the writers314of the second outer module304are positioned to write simultaneously therewith.

Actuators described in this and other embodiments described herein may include any type of conventional actuator. According to various embodiments, the first actuator308may include, e.g., a worm screw, a piezo stack, a microscopic voice coil magnet assembly, a micro eletro mechanical structure (MEMS) device, etc. The first actuator308may additionally and/or alternatively include a biasing mechanism, e.g., a spring, which may be used to retract the outer module(s)302,306from a most previous shifting motion to a nominal position. Actuator springs will be described in greater detail elsewhere herein, e.g., seeFIGS. 8-9B.

Shifting the first outer module302, relative to the inner module304, in a cross-track direction may allow the writers of the first outer module302and the second outer module306to simultaneously write separate data tracks, at twice the rate achievable when only one of the modules is used. In other words, shifting the first outer module302in the system300ofFIG. 3may allow the 16 total writers of the outer modules302,306to write 16 separate data tracks on a magnetic recording tape that is passed over the writers314. These 16 separate data tracks include 8 more written data tracks than would be written if the first outer module302were not shifted by the actuator308. This is because, as previously described, in the un-shifted position, the writers314of the first outer module302align with writers314of the second outer module306along the first direction316and the writers314thereby are only able to write 8 data tracks (in the present example). Likewise, where each module has an array of 32 writers, the shift may correspond to a simultaneous writing potential of 64 data channels as opposed to 32 data channels.

Referring now toFIG. 4, the tape may be passed over each of the modules302,304,306in a second direction402. The second direction402may be substantially opposite the first direction316ofFIG. 3.

The second actuator310may shift the second outer module306. According to various embodiments, the second actuator310may shift the second outer module306relative to the inner module304. The shift may be about one half of a center-to-center pitch404of the writers314of the second outer module306when writing in the direction402in which the first outer module302is the leading module, or some other distance.

Shifting the second outer module306, relative to the inner module304, in the cross-track direction may allow each of the writers314of the first outer module302and the second outer module306to simultaneously write separate data tracks in the second direction402of tape travel.

It should be noted that inFIGS. 3 and 4, the dashed lines “320” represent data tracks320that may be written to a tape that passes over the modules302,304,306. The data tracks320are written by the writers314of both outer modules302,306. As shown inFIGS. 3-4, preferably the tracks written by the writers314of the leading module, as determined by tape travel direction, are aligned with the readers312of the inner module304, thereby allowing read-while-write verification of the data tracks written by the leading module. While the tracks written by the trailing module are not immediately read-verified in the embodiment shown inFIGS. 3-4, the data may be verified later, or simply not verified.

The apparatus318may include a drive mechanism to pass a magnetic recording tape over each of the modules302,304,306. Apparatus318may also include a controller electrically coupled to the readers312and writers314. In the present illustrative embodiment, the controller may be configured to read-verify tracks written by writers314of the outer modules302,306using signals from the readers312of the inner module304. An illustrative drive and controller are described elsewhere herein, e.g., seeFIG. 1A.

As is illustrated inFIG. 5, system300may include three cables516that enable both conventional bi-directional read-while-write writing of 8 data tracks, and simultaneous writing of 16 data tracks. Accordingly, the first actuator308desirably enables an increase in the number of available write channels without the need for extra head cables. This is especially desirable because adding extra cables may undesirably crowd the tight and compact spatial constraints in a drive; and moreover, the stiffness of the additional cables would be expected to adversely affect the performance of the track following actuator. In comparison, an implemented first actuator308, and even an additionally implemented second actuator (as will be described elsewhere herein), may preferably be very small in size.

It should be noted that although sixteen data tracks320corresponding to sixteen writers, are illustrated inFIG. 3, system300may include any number of data channels according to other embodiments. For example, according to one approach, the system300may include 32 writers. According to another approach, the system300may include 32 writers. According to yet another approach, the system300may include 64 writers. Moreover, the number of readers of the inner module304relative to the number of writers of the outer modules302,306may vary, depending on the embodiment.

According to various embodiments, apparatus318may additionally and/or alternatively include a skew compensation actuator (not shown). As tape is passed over the modules302,304,306, the skew compensation actuator may rotate the modules302,304,306to compensate for tape skew.

According to other embodiments, the modules302,304,306may be coupled to a conventional two-stage actuator, e.g., a coarse and fine track following two-stage actuator, with the first and second actuators308,310providing the aforementioned further movement of the respective module. In various embodiments, a skew following function may also be enabled if desirable.

FIG. 5illustrates a partial tape bearing surface view of system300in accordance with one embodiment. The modules302,304,306each have a tape bearing surface502,504,506respectively, which may be flat, contoured, etc. Note that while the term “tape bearing surface” appears to imply that the tape508is in physical contact with the tape bearing surface, this is not necessarily the case. Rather, only a portion of the tape508may be in contact with the tape bearing surface, constantly or intermittently, with other portions of the tape riding (or “flying”) above the tape bearing surface on a layer of air, sometimes referred to as an “air bearing”. The first outer module302will be referred to as the “leading module302” in the descriptions ofFIG. 5as it is the first module encountered by the tape508in a three module design for tape moving in the second direction402. The second outer module306will be referred to as the “trailing module306”. The trailing module306follows the inner module304and is the last module seen by the tape508in a three module design. Note that the outer modules302,306will alternate as leading modules, depending on the direction of travel of the tape508.

In one embodiment, the tape bearing surfaces502,504,506of the modules302,304,306lie along planes slightly angled with respect to each other, and the tape bearing surface504of the inner module304is above the tape bearing surfaces502,506of the leading and trailing modules302,306. As described below, this has the effect of creating the desired wrap angle α2of the tape508relative to the tape bearing surface504of the inner module304.

Depending on tape tension and stiffness, it may be desirable to angle the tape bearing surfaces of the outer modules302,306relative to the tape bearing surface of the inner module304. InFIG. 5, the modules are in a tangent or nearly tangent (angled) configuration. Particularly, the tape bearing surfaces of the outer modules are about parallel to the tape at the desired wrap angle α2of the second outer module. In other words, the planes of the tape bearing surfaces502,506of the outer modules are oriented at about the desired wrap angle α2of the tape508relative to the inner module304.

The inner wrap angle α2on the side of the inner module304receiving the tape (leading edge) and the inner wrap angle α3on the trailing edge of the inner module304may vary depending on the embodiment. In preferred approaches, the wrap angles α2, α3are adjusted such that the tape508is passed over the tape bearing surfaces502,506of the leading and trailing modules302,306such that each of the writers314of such modules302,306may simultaneously write separate data tracks.

As described elsewhere herein (seeFIGS. 3-4) to enable the writers314of the leading and trailing modules302,306to simultaneously write separate data tracks, according to various embodiments, a first actuator308may shift the leading module302relative to the inner module304, in a cross-track direction by about one half of a center-to-center pitch of the writers314of the leading module302. Likewise, the second actuator310may shift the trailing module306relative to the inner module304, in a cross-track direction by about one half of a center-to-center pitch of the writers314of the trailing module306.

The actuators308,310may reside on and/or contact a support520of any type that would become apparent to one skilled in the art upon reading the present disclosure. In one approach, the support may be a conventional head carriage, modified to accommodate the actuators308,310.

Writing and reading functions may be performed by different modules302,304,306at any given time. In one embodiment, the inner module304includes a plurality of data readers312and optional servo readers (not shown) but no writers. The leading and trailing modules302,306include a plurality of writers314and no data readers, with the exception that the leading and trailing modules302,306may include optional servo readers. The servo readers may be used to position the head during reading and/or writing operations. The servo reader(s) on each module302,304,306are typically located toward the ends of the arrays of readers or writers. Note that other embodiments described herein may or may not include servo readers, e.g., of conventional type, adjacent one or more of the arrays.

In some embodiments, the inner module304has a closure518, while the leading and trailing modules302,306do not have a closure. Where there is no closure, preferably a hard coating is added to the outer modules302,306. One preferred coating is diamond-like carbon (DLC). In other approaches, the outer modules302,306each have a closure.

It should be noted that apparatus318may according to other embodiments be used where modules are configured in an overwrap configuration. Such embodiments will be described elsewhere herein, e.g., seeFIG. 11.

In an alternate embodiment, an actuator may additionally and/or alternatively be configured to shift the inner module of a multi-module head, e.g., seeFIGS. 6A-7.

FIGS. 6A-7depict a system600in accordance with one embodiment. As an option, the present system600may be implemented in conjunction with features from any other embodiment listed herein, such as those described with reference to the other FIGS. Of course, however, such system600and others presented herein may be used in various applications and/or in permutations which may or may not be specifically described in the illustrative embodiments listed herein. Further, the system600presented herein may be used in any desired environment.

It should be noted that various components of system600are similar to one or more components of system300ofFIGS. 3-5. Accordingly, one or more components of system600may share a common component numbering with one or more components of system300, and/or other systems described elsewhere herein.

Referring now toFIG. 6A, system600includes an apparatus608. The apparatus608may be a portion of the system600. Apparatus608includes a first outer module602having an array of writers314. Apparatus608may also include a second outer module606having an array of writers314.

According to one embodiment, as illustrated inFIGS. 6A-6B, the writers314of the second outer module606may be offset from the writers314of the first outer module602in a cross-track direction by about one half of a center-to-center pitch616of the writers314of the second outer module606. According to various embodiments, the positions of the first and second outer modules602,606may be fixed relative to one another.

Apparatus608may also include an inner module604positioned between the outer modules602,606. The inner module604may have an array of readers312.

Apparatus608may include an actuator614for shifting the inner module604, relative to the outer modules602,606. The actuator614for shifting the inner module604may selectively align the readers312with the writers314the leading outer module, depending on tape travel direction. In response to selectively aligning the readers312with the writers314of the leading outer module, during writing, the readers312of the inner module304may read-verify the data tracks written by the leading outer module.

Read verification in each tape travel direction will now be further detailed using a descriptive comparison ofFIGS. 6A-6B. Referring first toFIG. 6A, the first outer module602is the leading write module and the second outer module606is the trailing write module in the first tape travel direction610, as shown inFIG. 6A. In response to an instruction to move the tape in the first tape travel direction610, actuator614preferably shifts the inner module604to a position that selectively aligns the readers312of the inner module604with the writers314of the first outer module602. During tape travel in the first direction610, this selective alignment allows the writers314of the first outer module602to write data tracks, and then the readers312of the inner module604to read-verify those data tracks as the written data tracks pass over the readers312.

In contrast, referring now toFIG. 6B, the second outer module606is the leading write module as the tape moves in the second tape travel direction612. In response to an instruction to move the tape in the second tape travel direction612, actuator614preferably shifts the inner module604to a position that selectively aligns the readers312of the inner module604with the writers314of the second outer module606. During tape travel in the second direction612, this selective alignment allows the writers314of the second outer module606to write data tracks, and then the readers312of the inner module604to read-verify those data tracks as the written data tracks pass over the readers312.

According to various embodiments, the data tracks written by the trailing one of the outer modules602,606may not be read-verified during a particular direction of tape travel. In such embodiments, the data tracks written by the trailing one of the outer modules602,606may however be read-verified in a second pass of the magnetic tape over the modules602,604,606. For example, referring again toFIG. 6A, the data tracks written by the trailing outer module606may not be read-verified as the tape travels in the first direction610, e.g., during a first pass of the magnetic tape over the modules602,604,606. The data tracks written by the trailing outer module606during a first passing of the tape over the modules602,604,606may however be read-verified by the readers312of the inner module604during a second pass of the magnetic tape over the modules602,604,606, e.g., at the request of a user or host, when the drive has no read or write requests pending (e.g., idle time), etc.

Referring now toFIG. 7, a side view of the modules602,604,606of system600is illustrated in accordance with one embodiment. InFIG. 7, the modules are in a tangent or nearly tangent (angled) configuration.

A tape508is illustrated traveling in a first tape travel direction610inFIG. 7. Consequently, the first outer module602is the leading write module. Actuator614may shift the inner module604to a position that selectively aligns the readers312of the inner module604with the writers314of the first outer module602, thereby enabling read-verification of data tracks written by writers314of the first outer module602.

The actuator614may reside on and/or contact a support702of any type.

FIG. 8-9Bdepict systems800,900in accordance with various embodiments whereby illustrative actuators shift one or more modules of a three module head by exerting a force on one or more other modules. As an option, the present systems800,900may be implemented in conjunction with features from any other embodiment listed herein, such as those described with reference to the other FIGS. Of course, however, such systems800,900and others presented herein may be used in various applications and/or in permutations which may or may not be specifically described in the illustrative embodiments listed herein. Further, the systems800,900presented herein may be used in any desired environment.

Referring now toFIG. 8, system800includes an actuator824. Actuator824may be coupled to a plurality of modules, e.g., see outer modules802,822and an inner module804of system800.

Note thatFIG. 8illustrates a bottom view of the modules802,804,822and actuator824, e.g., readers and writers of the modules802,804,822may reside on an opposite side of the modules802,804,822not visible inFIG. 8.

Actuator824includes two preferably semi-rigid beams810,820. Each of the beams810,820may be coupled to two adjacent modules802and804,804and822, respectively, at or near opposite and alternate ends of the modules802,804,822. The coupling between the beams810,820and the modules802,804,822may be established using any conventional coupling type. According to various embodiments, the coupling may be established via, e.g., an adhesive, pins, solder, etc.

Actuator824may selectively cause a movement of each outer module802,822relative to the inner module804in an allowed direction of movement by exerting a force on the modules to which it is attached. For example, the outer module802may be shifted in a first direction808in response to a force being exerted on both the outer module802and the inner module804by beam810. According to another example, the outer module822may be shifted in the first direction808in response to a force being exerted on both the outer module822and the inner module804by beam820.

To hold the modules802,804,822in a desired position while allowing this motion, the modules802,804,822may be connected to one another by one or more springs812or other component(s) that allows flexing in the direction of motion. Note that the allowed direction of movement may be straight, or have a slight arc, depending on the particular design adopted for a given embodiment.

According to various embodiments, the actuator824may be a thermal actuator. In such embodiments, placing the coupling closer to the ends of the modules802,804,822may allow for the greatest amount of motion when using the thermal actuator.

In one approach, the actuator824comprises a preferably semi-rigid body, e.g., with beams810,820coupled to opposite ends of each adjacent module pair802and804,804and822. The beams810,820may be constructed of aluminum or other material with a coefficient of thermal expansion suitable for generating the desired expansion and/or contraction thereof. The temperature of all or a portion of the actuator824may be adjusted to induce the expansion and/or contraction thereof. One or both of the beams810,820may be heated via any suitable mechanism, including resistive (Joule) heating of the beams810,820themselves or of heating elements coupled thereto, raising of an ambient temperature, inductive heating, laser-induced heating, etc., The beams810,820may be cooled via any suitable mechanism, including by a Peltier device, by reducing or terminating application of heat thereto, etc. When one or both of the beams810,820may be heated, the thermal expansion creates a force that displaces one module with respect to another, e.g., module802relative to module804and/or module822relative to module804, and flexes the springs812.

Note that a second actuator of any type known in the art may be provided to tilt the assembly to achieve the desired pitch of the transducers relative to the tape and/or for skew compensation. The extent of the relative movement needed to align the modules802,804,822may be dependent upon a degree of tilting.

In another embodiment, the actuator824may be made of piezoelectric material such as PZT, or comprise multiple cells of piezoelectric material. In this case, a voltage is applied to the actuator824to create relative motion between the modules. In general, any actuator material know in the art can be used, such as shape memory alloys, bi-metallic strips, piezoelectric materials, etc.

Referring now toFIGS. 9A-9B, system900includes an actuator918. Actuator918may be positioned on over a plurality of modules, e.g., see first and second outer modules912,914and an inner module920of system900. Note thatFIGS. 9A-9Bare bottom and side views, respectively, of the modules912,914,920and actuator918, e.g., readers and/or writers of the modules912,914,920may reside on an opposite side of the modules912,914,920as that shown inFIG. 9A.

As depicted inFIGS. 9A and 9B, the actuator918may include a first hollow frame922and a second hollow frame924. The first hollow frame922may have at least two arms926,928extending between points of coupling902,930, which couple the actuator918to the first outer module912and the inner module920. Similarly, the second hollow frame924may have at least two arms904,906extending between points of coupling908,910, which couple the actuator918to the second outer module914and the inner module920.

The openings in the first and second hollow frames922,924provide access to the center of the modules912,914,920for attaching a cable. The springs916as depicted are “C” shaped pieces attached to the ends of the modules912,914,920, but could have any suitable shape.

As illustrated inFIG. 9B, heating elements932may be placed on each of the arms926,928of the first frame922and/or each of the arms904,906of the second frame924, such that any of the arms926,928,904,906can be heated evenly and selectively, e.g., simultaneously in pairs. The actuator918in this or any other embodiment can be heated with any number of different techniques, such as passing current through the beam directly, a heating element on the beam, wrapping the beam in current carrying wire, etc. In addition or alternatively, the beam may be cooled using any suitable technique or mechanism, including those listed above.

The effectiveness of this thermal actuator can be increased by selecting a design which minimizes the heat transferred to the modules912,914,920. In such designs, attachment pins or adhesives may be comprised of a thermally insulating material. Likewise, a method of insulating the beam from the modules912,914,920, through use of a thermally insulating material at the attachment points may be used in any of the other embodiments. The insulation minimizes heating of the modules912,914,920and results in a maximal displacement for a given temperature.

FIG. 10depicts a method1000for using an actuator to selectively shift modules of a three module magnetic recording head and thereby enable simultaneous writing by multiple modules of the magnetic recording head, in accordance with one embodiment. As an option, the present method1000may be implemented to computer rack systems such as those shown in the other FIGS. described herein. Of course, however, this method1000and others presented herein may be used to establish security and selective access for a wide variety of devices and/or purposes which may or may not be related to the illustrative embodiments listed herein. Further, the methods presented herein may be carried out in any desired environment. Moreover, more or less operations than those shown inFIG. 10may be included in method1000, according to various embodiments. It should also be noted that any of the aforementioned features may be used in any of the embodiments described in accordance with the various methods.

Method1000may be performed as a tape drive-implemented method in a tape drive. As described in various embodiments elsewhere herein, the tape drive may include at least a first outer module having an array of writers, a second outer module having an array of writers, and an inner module positioned between the outer modules, where the inner module has an array of readers.

Operation1002of method1000includes shifting at least one of the modules by about one half of a center-to-center pitch of the readers of the inner module.

Operation1004of method1000includes simultaneously writing a plurality of data tracks on a magnetic recording tape using the outer modules. The data tracks written by a trailing one of the outer modules may be offset in a cross-track direction from the data tracks written by a leading one of the outer modules. As described elsewhere herein, simultaneously writing a plurality of data tracks on a magnetic recording tape using the outer modules may utilize the multiple writer modules for simultaneously writing two times the number of data tracks, as well as allowing read-verification of at least half of the written tracks.

Referring now toFIG. 11, a side view of modules1102,1104,1106are illustrated positioned in an overwrap configuration of a multi-module head system1100in accordance with one embodiment. As an option, the present system1100may be implemented in conjunction with features from any other embodiment listed herein, such as those described with reference to the other FIGS. Of course, however, such system1100and others presented herein may be used in various applications and/or in permutations which may or may not be specifically described in the illustrative embodiments listed herein. Further, the system1100presented herein may be used in any desired environment.

It should be noted that various components of system1100are similar to one or more components of systems300,600ofFIGS. 3-5 and 6A-7. Accordingly, one or more components of system1100may share common component numbering with one or more components of other systems described elsewhere herein.

FIG. 11illustrates an embodiment where the modules1102,1104,1106are in an overwrap configuration. Particularly, the tape bearing surfaces502,506of the outer modules1102,1106are angled slightly more than the tape508when set at the desired wrap angle α2relative to the second outer module1106. In this embodiment, the tape508does not pop off of the trailing module1106, allowing the trailing module1106to be used for writing. A preferred embodiment has shortened closures1110that allow closer gap-to-gap separation between the modules.

A 32 channel version of a multi-module head system1100may use cables516having leads on the same or smaller pitch as current 16 channel piggyback LTO modules, or alternatively the connections on the module may be organ-keyboarded for a 50% reduction in cable span. Over-under, writing pair unshielded cables may be used for the writers, as well as integrated servo readers.

The outer wrap angles α1may be set in the drive, such as by guides of any type known in the art, such as adjustable rollers, slides, etc. or alternatively by outriggers, which are integral to the head. For example, rollers having an offset axis may be used to set the wrap angles. The offset axis creates an orbital arc of rotation, allowing precise alignment of the wrap angle α1.

To assemble any of the embodiments described above, conventional u-beam assembly can be used. Accordingly, the mass of the resultant head may be maintained or even reduced relative to heads of previous generations. Those skilled in the art, armed with the present teachings, will appreciate that other known methods of manufacturing such heads may be adapted for use in constructing such heads. Moreover, unless otherwise specified, processes and materials of types known in the art may be adapted for use in various embodiments in conformance with the teachings herein, as would become apparent to one skilled in the art upon reading the present disclosure.

As a tape is run over a module, it is preferred that the tape passes sufficiently close to magnetic transducers on the module such that reading and/or writing is efficiently performed, e.g., with a low error rate. According to some approaches, tape tenting may be used to ensure the tape passes sufficiently close to the portion of the module having the magnetic transducers. To better understand this process,FIGS. 12A-12Cillustrate the principles of tape tenting.FIG. 12Ashows a module1200having an upper tape bearing surface1202extending between opposite edges1204,1206. A stationary tape1208is shown wrapping around the edges1204,1206. As shown, the bending stiffness of the tape1208lifts the tape off of the tape bearing surface1202. Tape tension tends to flatten the tape profile, as shown inFIG. 12A. Where tape tension is minimal, the curvature of the tape is more parabolic than shown.

FIG. 12Bdepicts the tape1208in motion. The leading edge, i.e., the first edge the tape encounters when moving, may serve to skive air from the tape, thereby creating a subambient air pressure between the tape1208and the tape bearing surface1202. InFIG. 12B, the leading edge is the left edge and the right edge is the trailing edge when the tape is moving left to right. As a result, atmospheric pressure above the tape urges the tape toward the tape bearing surface1202, thereby creating tape tenting proximate each of the edges. The tape bending stiffness resists the effect of the atmospheric pressure, thereby causing the tape tenting proximate both the leading and trailing edges. Modeling predicts that the two tents are very similar in shape.

FIG. 12Cdepicts how the subambient pressure urges the tape1208toward the tape bearing surface1202even when a trailing guide1210is positioned above the plane of the tape bearing surface.

It follows that tape tenting may be used to direct the path of a tape as it passes over a module. As previously mentioned, tape tenting may be used to ensure the tape passes sufficiently close to the portion of the module having the magnetic transducers, preferably such that reading and/or writing is efficiently performed, e.g., with a low error rate.

Magnetic tapes may be stored in tape cartridges that are, in turn, stored at storage slots or the like inside a data storage library. The tape cartridges may be stored in the library such that they are accessible for physical retrieval. In addition to magnetic tapes and tape cartridges, data storage libraries may include data storage drives that store data to, and/or retrieve data from, the magnetic tapes. Moreover, tape libraries and the components included therein may implement a file system which enables access to tape and data stored on the tape.

File systems may be used to control how data is stored in, and retrieved from, memory. Thus, a file system may include the processes and data structures that an operating system uses to keep track of files in memory, e.g., the way the files are organized in memory. Linear Tape File System (LTFS) is an exemplary format of a file system that may be implemented in a given library in order to enables access to compliant tapes. It should be appreciated that various embodiments herein can be implemented with a wide range of file system formats, including for example IBM Spectrum Archive Library Edition (LTFS LE). However, to provide a context, and solely to assist the reader, some of the embodiments below may be described with reference to LTFS which is a type of file system format. This has been done by way of example only, and should not be deemed limiting on the invention defined in the claims.

A tape cartridge may be “loaded” by inserting the cartridge into the tape drive, and the tape cartridge may be “unloaded” by removing the tape cartridge from the tape drive. Once loaded in a tape drive, the tape in the cartridge may be “threaded” through the drive by physically pulling the tape (the magnetic recording portion) from the tape cartridge, and passing it above a magnetic head of a tape drive. Furthermore, the tape may be attached on a take-up reel (e.g., see121ofFIG. 1Aabove) to move the tape over the magnetic head.

Once threaded in the tape drive, the tape in the cartridge may be “mounted” by reading metadata on a tape and bringing the tape into a state where the LTFS is able to use the tape as a constituent component of a file system. Moreover, in order to “unmount” a tape, metadata is preferably first written on the tape (e.g., as an index), after which the tape may be removed from the state where the LTFS is allowed to use the tape as a constituent component of a file system. Finally, to “unthread” the tape, the tape is unattached from the take-up reel and is physically placed back into the inside of a tape cartridge again. The cartridge may remain loaded in the tape drive even after the tape has been unthreaded, e.g., waiting for another read and/or write request. However, in other instances, the tape cartridge may be unloaded from the tape drive upon the tape being unthreaded, e.g., as described above.

Magnetic tape is a sequential access medium. Thus, new data is written to the tape by appending the data at the end of previously written data. It follows that when data is recorded in a tape having only one partition, metadata (e.g., allocation information) is continuously appended to an end of the previously written data as it frequently updates and is accordingly rewritten to tape. As a result, the rearmost information is read when a tape is first mounted in order to access the most recent copy of the metadata corresponding to the tape. However, this introduces a considerable amount of delay in the process of mounting a given tape.

To overcome this delay caused by single partition tape mediums, the LTFS format includes a tape that is divided into two partitions, which include an index partition and a data partition. The index partition may be configured to record metadata (meta information), e.g., such as file allocation information (Index), while the data partition may be configured to record the body of the data, e.g., the data itself.

Looking toFIG. 13, a magnetic tape1300having an index partition1302and a data partition1304is illustrated according to one embodiment. As shown, data files and indexes are stored on the tape. The LTFS format allows for index information to be recorded in the index partition1302at the beginning of tape1306, as would be appreciated by one skilled in the art upon reading the present description.

As index information is updated, it preferably overwrites the previous version of the index information, thereby allowing the currently updated index information to be accessible at the beginning of tape in the index partition. According to the specific example illustrated inFIG. 13, a most recent version of metadata Index 3 is recorded in the index partition1302at the beginning of the tape1306. Conversely, all three version of metadata Index 1, Index 2, Index 3 as well as data File A, File B, File C, File D are recorded in the data partition1304of the tape. Although Index 1 and Index 2 are old (e.g., outdated) indexes, because information is written to tape by appending it to the end of the previously written data as described above, these old indexes Index 1, Index 2 remain stored on the tape1300in the data partition1304without being overwritten.

The metadata may be updated in the index partition1302and/or the data partition1304differently depending on the desired embodiment. According to some embodiments, the metadata of the index partition1302may be updated in response to the tape being unmounted, e.g., such that the index may be read from the index partition when that tape is mounted again. The metadata may also be written in the data partition1304so the tape may be mounted using the metadata recorded in the data partition1304, e.g., as a backup option.

According to one example, which is no way intended to limit the invention, LTFS LE may be used to provide the functionality of writing an index in the data partition when a user explicitly instructs the system to do so, or at a time designated by a predetermined period which may be set by the user, e.g., such that data loss in the event of sudden power stoppage can be mitigated.