Patent Publication Number: US-11664048-B2

Title: Multi-spool tape recording apparatus

Description:
BACKGROUND 
     The present invention relates to data storage systems, and more particularly, this invention relates to an apparatus using multiple spools of magnetic tape to dramatically improve data access times. 
     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 challenges ranging from the design of tape head assemblies for use in such systems to dealing with tape dimensional instability. 
     In the near future, with the adoption of improved media, the cost of storing information (on a per byte basis) on tape is expected to decline by a factor of five or more with respect to magnetic disk. Also, short-term and long-term reliability will continue to favor tape-based storage. Furthermore, as more mass storage is allocated to cloud networks, most storage will be in large libraries, rather than on individual drives, which is a consideration favoring tape-based storage. One historical disadvantage of tape-based storage with respect to disk-based storage was the relatively poor access time associated with tape-based storage, with the time required to bring the tape to the tape drive and then spool the tape to the file location typically averaging about 40 seconds. 
     SUMMARY 
     An apparatus, in accordance with one approach, includes a receiving area configured to receive a plurality of tape spool pairs. A drive mechanism is configured to selectively drive the tape spool pairs. A magnetic head configured to perform data operations on magnetic recording tapes of the tape spool pairs is also present. A positioning mechanism is configured to selectively align the magnetic head to a selected one of the tape spool pairs. An engagement mechanism is configured to create a relative movement between the magnetic head and the magnetic recording tape of the selected tape spool pair for engaging the magnetic recording tape with the magnetic head. A controller is configured to instruct the drive mechanism to drive the selected tape spool pair during performance of data operations on the selected tape spool pair, and to instruct the drive mechanism to drive a second tape spool pair for performing a second operation on the second tape spool pair while the data operations are being performed. 
     A method, in accordance with one approach, includes instructing an engagement mechanism to create a relative movement between a magnetic head and a magnetic recording tape of a selected tape spool pair of a plurality of tape spool pairs that are positioned in a receiving area of an apparatus, thereby causing an engagement of the magnetic recording tape with the magnetic head. A drive mechanism is instructed to drive the selected tape spool pair. A magnetic head is caused to perform data operations on the magnetic recording tape of the selected tape spool pair. The drive mechanism is also instructed to drive a second of the tape spool pairs for performing a second operation on the second tape spool pair while the data operations are being performed. 
     A computer program product for performing data operations on magnetic recording tape, in accordance with one approach, includes a computer readable storage medium having program instructions embodied therewith. The program instructions are executable by an apparatus, such as the apparatus described above and/or in other approaches described herein to cause the apparatus to perform the foregoing method. 
     An apparatus, in accordance with another approach, includes a receiving area configured to receive a plurality of tape spool pairs. A drive mechanism is configured to selectively drive the tape spool pairs. Multiple magnetic heads are configured to perform data operations on magnetic recording tapes of the tape spool pairs. An engagement mechanism is configured to create a relative movement between the magnetic heads and the magnetic recording tapes to be operated on for engaging the magnetic recording tapes with the magnetic heads. 
     The apparatus described immediately above improves on the access time over approaches with a smaller number of magnetic heads by allowing more concurrent data operations when multiple heads are in operation simultaneously. 
     Other aspects and approaches 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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  is a schematic diagram of a simplified tape drive system according to one approach. 
         FIG.  1 B  is a schematic diagram of a tape cartridge according to one approach. 
         FIG.  2 A  illustrates a side view of a flat-lapped, bi-directional, two-module magnetic tape head according to one approach. 
         FIG.  2 B  is a tape bearing surface view taken from Line  2 B of  FIG.  2 A . 
         FIG.  2 C  is a detailed view taken from Circle  2 C of  FIG.  2 B . 
         FIG.  2 D  is a detailed view of a partial tape bearing surface of a pair of modules. 
         FIG.  3    is a partial tape bearing surface view of a magnetic head having a write-read-write configuration. 
         FIG.  4    is a partial tape bearing surface view of a magnetic head having a read-write-read configuration. 
         FIG.  5    is a side view of a magnetic tape head with three modules according to one approach where the modules all generally lie along about parallel planes. 
         FIG.  6    is a side view of a magnetic tape head with three modules in a tangent (angled) configuration. 
         FIG.  7    is a side view of a magnetic tape head with three modules in an overwrap configuration. 
         FIGS.  8 A- 8 C  are schematics depicting the principles of tape tenting. 
         FIG.  9    is a representational diagram of files and indexes stored on a magnetic tape according to one approach. 
         FIG.  10    is a representational view of an apparatus in accordance with one approach. 
         FIG.  11    is a representational view of an apparatus in accordance with one approach. 
         FIG.  12    is a representational view of an apparatus in accordance with one approach. 
         FIG.  13 A  is a representational view of an apparatus in accordance with one approach. 
         FIG.  13 B  is a representational view of an apparatus in accordance with one approach. 
         FIG.  13 C  is a representational view of an apparatus in accordance with one approach. 
         FIGS.  14 A and  14 B  are representational views of an apparatus in accordance with one approach. 
         FIGS.  14 C and  14 D  are representational views of an apparatus in accordance with one approach. 
         FIGS.  15 A and  15 B  are representational views of an apparatus in accordance with one approach. 
         FIG.  16    is a flowchart of a method in accordance with one approach. 
         FIG.  17    is a flowchart of a method in accordance with one approach. 
         FIG.  18    is a flowchart of a method in accordance with one approach. 
         FIG.  19    is a flowchart of a method in accordance with one approach. 
     
    
    
     DETAILED DESCRIPTION 
     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. 
     It must also be noted that, as used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless otherwise specified. 
     The following description discloses several preferred approaches of magnetic storage systems, as well as operation and/or component parts thereof. 
     In one general approach, an apparatus includes a receiving area configured to receive a plurality of tape spool pairs. A drive mechanism is configured to selectively drive the tape spool pairs. A magnetic head configured to perform data operations on magnetic recording tapes of the tape spool pairs is also present. A positioning mechanism is configured to selectively align the magnetic head to a selected one of the tape spool pairs. An engagement mechanism is configured to create a relative movement between the magnetic head and the magnetic recording tape of the selected tape spool pair for engaging the magnetic recording tape with the magnetic head. 
     In another general approach, a method includes instructing a positioning mechanism to selectively align a magnetic head to a selected tape spool pair of a plurality of tape spool pairs that are positioned in a receiving area of an apparatus, such as the apparatus described above and/or in other approaches described herein. An engagement mechanism is instructed to create a relative movement between the magnetic head and a magnetic recording tape of the selected tape spool pair for engaging the magnetic recording tape with the magnetic head. A drive mechanism is instructed to drive the selected tape spool pair. A magnetic head is caused to perform data operations on the magnetic recording tape of the selected tape spool pair. 
     In another general approach, a computer program product for performing data operations on magnetic recording tape includes a computer readable storage medium having program instructions embodied therewith. The program instructions are executable by an apparatus, such as the apparatus described above and/or in other approaches described herein to cause the apparatus to perform the foregoing method. 
     In another general approach, an apparatus includes a receiving area configured to receive a plurality of tape spool pairs. A drive mechanism is configured to selectively drive the tape spool pairs. Multiple magnetic heads are configured to perform data operations on magnetic recording tapes of the tape spool pairs. An engagement mechanism is configured to create a relative movement between the magnetic heads and the magnetic recording tapes to be operated on for engaging the magnetic recording tapes with the magnetic heads. 
       FIG.  1 A  illustrates a simplified tape drive  100  of 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 in  FIG.  1 A , it should be noted that the approaches described herein may be implemented in the context of any type of tape drive system. 
     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 cartridge and are not necessarily part of the tape drive  100 . The tape drive, such as that illustrated in  FIG.  1 A , may further include drive motor(s) to drive the tape supply cartridge  120  and the take-up reel  121  to move the tape  122  over a tape head  126  of any type. Such head may include an array of readers, writers, or both. 
     Guides  125  guide the tape  122  across the tape head  126 . Such tape head  126  is in turn coupled to a controller  128  via a cable  130 . The controller  128 , may be or include a processor and/or any logic for controlling any subsystem of the drive  100 . For example, the controller  128  typically controls head functions such as servo following, data writing, data reading, etc. The controller  128  may 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 tape  122 . The controller  128  may 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 approaches. The controller  128  may be coupled to a memory  136  of any known type, which may store instructions executable by the controller  128 . Moreover, the controller  128  may be configured and/or programmable to perform or control some or all of the methodology presented herein. Thus, the controller  128  may 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 cable  130  may include read/write circuits to transmit data to the tape head  126  to be recorded on the tape  122  and to receive data read by the tape head  126  from the tape  122 . An actuator  132  controls position of the tape head  126  relative to the tape  122 . 
     An interface  134  may also be provided for communication between the tape drive  100  and a host (internal or external) to send and receive the data and for controlling the operation of the tape drive  100  and communicating the status of the tape drive  100  to the host, all as will be understood by those of skill in the art. 
       FIG.  1 B  illustrates an exemplary tape cartridge  150  according to one approach. Such tape cartridge  150  may be used with a system such as that shown in  FIG.  1 A . As shown, the tape cartridge  150  includes a housing  152 , a tape  122  in the housing  152 , and a nonvolatile memory  156  coupled to the housing  152 . In some approaches, the nonvolatile memory  156  may be embedded inside the housing  152 , as shown in  FIG.  1 B . In more approaches, the nonvolatile memory  156  may be attached to the inside or outside of the housing  152  without modification of the housing  152 . For example, the nonvolatile memory may be embedded in a self-adhesive label  154 . In one preferred approach, the nonvolatile memory  156  may be a Flash memory device, read-only memory (ROM) device, etc., embedded into or coupled to the inside or outside of the tape cartridge  150 . 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.  2 A  illustrates a side view of a flat-lapped, bi-directional, two-module magnetic tape head  200  which may be implemented in the context of the present invention. As shown, the head includes a pair of bases  202 , each equipped with a module  204 , and fixed at a small angle α with respect to each other. The bases may be “U-beams” that are adhesively coupled together. Each module  204  includes a substrate  204 A and a closure  204 B with a thin film portion, commonly referred to as a “gap” in which the readers and/or writers  206  are formed. In use, a tape  208  is moved over the modules  204  along a media (tape) bearing surface  209  in the manner shown for reading and writing data on the tape  208  using the readers and writers. The wrap angle θ of the tape  208  at edges going onto and exiting the flat media support surfaces  209  are usually between about 0.1 degree and about 3 degrees. 
     The substrates  204 A are typically constructed of a wear resistant material, such as a ceramic. The closures  204 B may be made of the same or similar ceramic as the substrates  204 A. 
     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.  2 B  illustrates the tape bearing surface  209  of one of the modules  204  taken from Line  2 B of  FIG.  2 A . A representative tape  208  is shown in dashed lines. The module  204  is preferably long enough to be able to support the tape as the head steps between data bands. 
     In this example, the tape  208  includes 4 to 32 data bands, e.g., with 16 data bands and 17 servo tracks  210 , as shown in  FIG.  2 B  on a one-half inch wide tape  208 . The data bands are defined between servo tracks  210 . 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 writers  206  are positioned to specific track positions within one of the data bands. Outer readers, sometimes called servo readers, read the servo tracks  210 . The servo signals are in turn used to keep the readers and/or writers  206  aligned with a particular set of tracks during the read/write operations. 
       FIG.  2 C  depicts a plurality of readers and/or writers  206  formed in a gap  218  on the module  204  in Circle  2 C of  FIG.  2 B . As shown, the array of readers and writers  206  includes, for example, 16 writers  214 , 16 readers  216  and two servo readers  212 , though the number of elements may vary. Illustrative approaches include 8, 16, 32, 40, and 64 active readers and/or writers  206  per array, and alternatively interleaved designs having odd numbers of reader or writers such as 17, 25, 33, etc. An illustrative approach 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 in  FIG.  2 C , the readers  216  and writers  214  may also be arranged in an interleaved configuration. Alternatively, each array of readers and/or writers  206  may be readers or writers only, and the arrays may contain one or more servo readers  212 . As noted by considering  FIGS.  2 A and  2 B- 2 C  together, each module  204  may include a complementary set of readers and/or writers  206  for such things as bi-directional reading and writing, read-while-write capability, backward compatibility, etc. 
       FIG.  2 D  shows a partial tape bearing surface view of complementary modules of a magnetic tape head  200  according to one approach. In this approach, each module has a plurality of read/write (R/W) pairs in a piggyback configuration formed on a common substrate  204 A and an optional electrically insulative insulating layer  236 . The writers  214  and the readers  216  are aligned parallel to an intended direction of travel of a tape medium thereacross to form an RAY pair, exemplified by RAY pairs  222 . 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 pairs  222  may be present, such as 8, 16, 32 pairs, etc. The R/W pairs  222  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  212  are positioned on the outside of the array of RAY 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  220 . The magnetic tape medium and head assembly  200  operate in a transducing relationship in the manner well-known in the art. The head assembly  200  includes two thin-film modules  224  and  226  of generally identical construction. 
     Modules  224  and  226  are joined together with a space present between closures  204 B 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  224 ,  226  of a magnetic tape head  200  is constructed, layers are formed in the gap  218  created above an electrically conductive substrate  204 A (partially shown), e.g., of AlTiC, in generally the following order for the RAY pairs  222 : an insulating layer  236 , a first shield  232  typically of an iron alloy such as NiFe (−), cobalt zirconium tantalum (CZT) or Al—Fe—Si (Sendust), a sensor  234  for sensing a data track on a magnetic medium, a second shield  238  typically of a nickel-iron alloy (e.g., ˜80/20 at % NiFe, also known as permalloy), first and second writer poles  228 ,  230 , and a coil (not shown). The sensor may be of any known type, including those based on magnetoresistive (MR), GMR, AMR, tunneling magnetoresistance (TMR), etc. 
     The first and second writer poles  228 ,  230  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. 
     The configuration of the tape head  126  according to one approach 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. Referring to  FIG.  3   , depicting a W-R-W configuration, the outer modules  252 ,  256  each include one or more arrays of writers  260 . The inner module  254  of  FIG.  3    includes one or more arrays of readers  258  in a similar configuration. Variations of a multi-module head include a R-W-R head ( FIG.  4   ), a R-R-W head, a W-W-R head, etc. In yet other variations, 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 approaches of the present invention. One skilled in the art apprised with the teachings herein will appreciate how permutations of the present invention would apply to configurations other than a W-R-W configuration. 
       FIG.  5    illustrates a magnetic head  126  according to one approach of the present invention that includes first, second and third modules  302 ,  304 ,  306  each having a tape bearing surface  308 ,  310 ,  312  respectively, which may be flat, contoured, etc. Note that while the term “tape bearing surface” appears to imply that the surface facing the tape  315  is in physical contact with the tape bearing surface, this is not necessarily the case. Rather, only a portion of the tape may 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 module  302  will be referred to as the “leading” module as it is the first module encountered by the tape in a three module design for tape moving in the indicated direction. The third module  306  will be referred to as the “trailing” module. The trailing module follows the middle module and is the last module seen by the tape in a three module design. The leading and trailing modules  302 ,  306  are referred to collectively as outer modules. Also note that the outer modules  302 ,  306  will alternate as leading modules, depending on the direction of travel of the tape  315 . 
     In one approach, the tape bearing surfaces  308 ,  310 ,  312  of the first, second and third modules  302 ,  304 ,  306  lie on about parallel planes (which is meant to include parallel and nearly parallel planes, e.g., between parallel and tangential as in  FIG.  6   ), and the tape bearing surface  310  of the second module  304  is above the tape bearing surfaces  308 ,  312  of the first and third modules  302 ,  306 . As described below, this has the effect of creating the desired wrap angle α 2  of the tape relative to the tape bearing surface  310  of the second module  304 . 
     Where the tape bearing surfaces  308 ,  310 ,  312  lie along parallel or nearly parallel yet offset planes, intuitively, the tape should peel off of the tape bearing surface  308  of the leading module  302 . However, the vacuum created by a skiving edge  318  of the leading module  302  has been found by experimentation to be sufficient to keep the tape adhered to the tape bearing surface  308  of the leading module  302 . A trailing edge  320  of the leading module  302  (the end from which the tape leaves the leading module  302 ) is the approximate reference point which defines the wrap angle α 2  over the tape bearing surface  310  of the second module  304 . The tape stays in close proximity to the tape bearing surface until close to the trailing edge  320  of the leading module  302 . Accordingly, transducers  322  may be located near the trailing edges of the outer modules  302 ,  306 . These approaches are particularly adapted for write-read-write applications. 
     A benefit of this and other approaches described herein is that, because the outer modules  302 ,  306  are fixed at a determined offset from the second module  304 , the inner wrap angle α 2  is fixed when the modules  302 ,  304 ,  306  are coupled together or are otherwise fixed into a head. The inner wrap angle α 2  is approximately tan −1 (δ/W) where δ is the height difference between the planes of the tape bearing surfaces  308 ,  310  and W is the width between the opposing ends of the tape bearing surfaces  308 ,  310 . An illustrative inner wrap angle α 2  is in a range of about 0.3° to about 1.1°, though can be any angle required by the design. 
     Beneficially, the inner wrap angle α 2  on the side of the module  304  receiving the tape (leading edge) will be larger than the inner wrap angle α 3  on the trailing edge, as the tape  315  rides above the trailing module  306 . This difference is generally beneficial as a smaller α 3  tends to oppose what has heretofore been a steeper exiting effective wrap angle. 
     Note that the tape bearing surfaces  308 ,  312  of the outer modules  302 ,  306  are positioned to achieve a negative wrap angle at the trailing edge  320  of the leading module  302 . This is generally beneficial in helping to reduce friction due to contact with the trailing edge  320 , provided that proper consideration is given to the location of the crowbar region that forms in the tape where it peels off the head. This negative wrap angle also reduces flutter and scrubbing damage to the elements on the leading module  302 . Further, at the trailing module  306 , the tape  315  flies over the tape bearing surface  312  so there is virtually no wear on the elements when tape is moving in this direction. Particularly, the tape  315  entrains air and so will not significantly ride on the tape bearing surface  312  of the third module  306  (some contact may occur). This is permissible, because the leading module  302  is writing while the trailing module  306  is idle. 
     Writing and reading functions are performed by different modules at any given time. In one approach, the second module  304  includes a plurality of data and optional servo readers  331  and no writers. The first and third modules  302 ,  306  include a plurality of writers  322  and no data readers, with the exception that the outer modules  302 ,  306  may 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 module are typically located towards the end of the array of readers or writers. 
     By having only readers or side by side writers and servo readers in the gap between the substrate and closure, the gap length can be substantially reduced. Typical heads have piggybacked readers and writers, where the writer is formed above each reader. A typical gap is 20-35 microns. However, irregularities on the tape may tend to droop into the gap and create gap erosion. Thus, the smaller the gap is the better. The smaller gap enabled herein exhibits fewer wear related problems. 
     In some approaches, the second module  304  has a closure, while the first and third modules  302 ,  306  do not have a closure. Where there is no closure, preferably a hard coating is added to the module. One preferred coating is diamond-like carbon (DLC). 
     In the approach shown in  FIG.  5   , the first, second, and third modules  302 ,  304 ,  306  each have a closure  332 ,  334 ,  336 , which extends the tape bearing surface of the associated module, thereby effectively positioning the read/write elements away from the edge of the tape bearing surface. The closure  332  on the second module  304  can be a ceramic closure of a type typically found on tape heads. The closures  334 ,  336  of the first and third modules  302 ,  306 , however, may be shorter than the closure  332  of the second module  304  as measured parallel to a direction of tape travel over the respective module. This enables positioning the modules closer together. One way to produce shorter closures  334 ,  336  is to lap the standard ceramic closures of the second module  304  an additional amount. Another way is to plate or deposit thin film closures above the elements during thin film processing. For example, a thin film closure of a hard material such as Sendust or nickel-iron alloy (e.g., 45/55) can be formed on the module. 
     With reduced-thickness ceramic or thin film closures  334 ,  336  or no closures on the outer modules  302 ,  306 , the write-to-read gap spacing can be reduced to less than about 1 mm, e.g., about 0.75 mm, or 50% less than commonly-used linear tape open (LTO) tape head spacing. The open space between the modules  302 ,  304 ,  306  can still be set to approximately 0.5 to 0.6 mm, which in some approaches is ideal for stabilizing tape motion over the second module  304 . 
     Depending on tape tension and stiffness, it may be desirable to angle the tape bearing surfaces of the outer modules relative to the tape bearing surface of the second module.  FIG.  6    illustrates an approach where the modules  302 ,  304 ,  306  are in a tangent or nearly tangent (angled) configuration. Particularly, the tape bearing surfaces of the outer modules  302 ,  306  are about parallel to the tape at the desired wrap angle α 2  of the second module  304 . In other words, the planes of the tape bearing surfaces  308 ,  312  of the outer modules  302 ,  306  are oriented at about the desired wrap angle α 2  of the tape  315  relative to the second module  304 . The tape will also pop off of the trailing module  306  in this approach, thereby reducing wear on the elements in the trailing module  306 . These approaches are particularly useful for write-read-write applications. Additional aspects of these approaches are similar to those given above. 
     Typically, the tape wrap angles may be set about midway between the approaches shown in  FIGS.  5  and  6   . 
       FIG.  7    illustrates an approach where the modules  302 ,  304 ,  306  are in an overwrap configuration. Particularly, the tape bearing surfaces  308 ,  312  of the outer modules  302 ,  306  are angled slightly more than the tape  315  when set at the desired wrap angle α 2  relative to the second module  304 . In this approach, the tape does not pop off of the trailing module, allowing it to be used for writing or reading. Accordingly, the leading and middle modules can both perform reading and/or writing functions while the trailing module can read any just-written data. Thus, these approaches are preferred for write-read-write, read-write-read, and write-write-read applications. In the latter approaches, closures should be wider than the tape canopies for ensuring read capability. The wider closures may require a wider gap-to-gap separation. Therefore, a preferred approach has a write-read-write configuration, which may use shortened closures that thus allow closer gap-to-gap separation. 
     Additional aspects of the approaches shown in  FIGS.  6  and  7    are similar to those given above. 
     A 32 channel version of a multi-module tape head  126  may use cables  350  having 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, which may have integrated servo readers. 
     The outer wrap angles α 1  may 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 α 1 . 
     To assemble any of the approaches 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. In other approaches, the modules may be constructed as a unitary body. 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 approaches 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.  8 A- 8 C  illustrate the principles of tape tenting.  FIG.  8 A  shows a module  800  having an upper tape bearing surface  802  extending between opposite edges  804 ,  806 . A stationary tape  808  is shown wrapping around the edges  804 ,  806 . As shown, the bending stiffness of the tape  808  lifts the tape off of the tape bearing surface  802 . Tape tension tends to flatten the tape profile, as shown in  FIG.  8 A . Where tape tension is minimal, the curvature of the tape is more parabolic than shown. 
       FIG.  8 B  depicts the tape  808  in 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 tape  808  and the tape bearing surface  802 . In  FIG.  8 B , 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 surface  802 , 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.  8 C  depicts how the subambient pressure urges the tape  808  toward the tape bearing surface  802  even when a trailing guide  810  is 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 approaches 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 approaches 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., see  121  of  FIG.  1 A  above) 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 to  FIG.  9   , a magnetic tape  900  having an index partition  902  and a data partition  904  is illustrated according to one approach. As shown, data files and indexes are stored on the tape. The LTFS format allows for index information to be recorded in the index partition  902  at the beginning of tape  906 , 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 in  FIG.  9   , a most recent version of metadata Index  3  is recorded in the index partition  902  at the beginning of the tape  906 . 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 partition  904  of 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 tape  900  in the data partition  904  without being overwritten. 
     The metadata may be updated in the index partition  902  and/or the data partition  904  the same or differently depending on the desired approach. According to some approaches, the metadata of the index and/or data partitions  902 ,  904  may be updated in response to the tape being unmounted, e.g., such that the index may be read quickly from the index partition when that tape is mounted again. The metadata is preferably also written in the data partition  904  so the tape may be mounted using the metadata recorded in the data partition  904 , 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. 
     While magnetic recording tape-based storage is by far the least expensive solution for storage of large quantities of data, as mentioned above, one particular disadvantage with current tape-based storage systems is the relatively long delay between receiving a request for data and returning the actual data from tape. This delay is due in part to the nature of tape. Often, a request for data is directed to a tape that is in storage in a tape library. Upon receiving the request for the data, the cartridge having the tape with the data thereon is typically moved from storage to an available drive, upon which the cartridge is loaded into the drive, the tape is mounted, and then the tape is indexed to the location of the data. As noted above, at best, this takes several tens of seconds. By comparison, a typical hard disk drive has about a 15 second spin up time and a 5 to 10 millisecond random access-type seek time. 
     Various approaches of the present invention include an apparatus that is capable of serving requests for data on tape in a fraction of the time typically required for cartridge-based tape library systems, while remaining economically viable. The speed is achieved in part by operating on an array of tape spool pairs each having a magnetic recording tape thereon. A magnetic head is selectively aligned with the tape spool pair having the tape with the requested data. Because the spools are not in cartridges, but rather remain present in the apparatus, the typical cartridge loading time is eliminated. Moreover, because seek time can increase with length of tape, each tape spool pair preferably has a length of tape selected to provide a desired average seek time. Finally, because a single head can service a plurality of the tape spool pairs, and preferably all of the tape spool pairs, the deployment cost remains far below disk-based storage and solid-state storage on a cost per unit storage basis. 
       FIGS.  10  and  11    depict an apparatus  1000  in accordance with one approach. As an option, the present apparatus  1000  may be implemented in conjunction with features from any other approach listed herein, such as those described with reference to the other FIGS. Of course, however, such apparatus  1000  and others presented herein may be used in various applications and/or in permutations which may or may not be specifically described in the illustrative approaches listed herein. Further, the apparatus  1000  presented herein may be used in any desired environment. 
     As shown in  FIGS.  10  and  11   , the apparatus  1000  includes a receiving area  1002  configured to receive a plurality of tape spool pairs  1004 .  FIG.  10    depicts the apparatus  1000  without tape spool pairs in the receiving area  1002 .  FIG.  11    depicts the apparatus  1000  without tape spool pairs  1004 . With continued reference to  FIGS.  10  and  11   , a drive mechanism  1006  is configured to selectively drive the tape spool pairs  1004 . A magnetic head  1008  is configured to perform data operations on magnetic recording tapes  1007  of the tape spool pairs  1004 . A positioning mechanism  1010  is configured to selectively align the magnetic head to a selected one of the tape spool pairs  1004  so that data operations may be performed. The engagement mechanism  1012  is configured to create a relative movement between the magnetic head  1008  and a magnetic recording tape  1007  of the selected one of the tape spool pairs  1004  for engaging the magnetic recording tape  1007  with the magnetic head  1008 . 
     The receiving area  1002  may be of any desired and/or practical size. In general, it should be large enough to accommodate the desired number of tape spool pairs  1004  usable at a given time in the apparatus  1000 . The receiving area  1002  may be defined by the interior of a housing  1014  of the apparatus  1000  in some approaches. The receiving area  1002  may be enclosed, open on top, accessible via a hatch in the housing  1014 , etc. In some aspects, tape spool pairs  1004  are mounted into the receiving area  1002 , and thus are not readily detachable. In the approach depicted, axles  1016 ,  1018  extend through a respective row of spools for supporting the spools. 
     In other aspects, tape spool pairs  1004  are readily removable from the receiving area  1002 . 
     Referring to  FIG.  11   , each tape spool pair  1004  includes a pair of spools  1004   a ,  1004   b  with a magnetic recording tape  1007  thereon. Any length of tape  1007  may be used in various approaches, as long as it fits on each spool. However, the maximum seek time for a given tape  1007  is proportional to its maximum length, e.g., the longest seek time occurs when a tape  1007  is wound entirely onto one spool and the desired data is accessible once the tape  1007  is wound almost entirely onto the other spool. Accordingly, the length of tape  1007  is preferably selected to provide a desired average or maximum seek time. By way of example, assuming a seek rate of 12 meters per second, a 360-meter-long tape  1007  should provide about a 15 second average seek time to access a single data object anywhere on the tape  1007 . 
     Similarly, the tape  1007  may have any desired width. In general, wider tapes  1007  can accommodate more data tracks, and therefore should be able to store more data per unit or tape length. A standard LTO tape is currently one-half inch wide. Such tape  1007  may be used in some approaches. In other approaches, the tape  1007  may be wider (e.g., about 1 inch wide, about 2 inches wide, about 4 inches wide, etc.) or narrower (e.g., about ⅓ inch wide, ¼ inch wide, etc.). 
     The tape  1007  may have any type of formatting. In a preferred approach, the tape  1007  is LTO compliant. 
     The tape spool pairs  1004  are driven by the drive mechanism  1006 . Any suitable type of drive mechanism  1006  may be used in various aspects, including known types of drive mechanisms  1006  adapted for use with the apparatus  1000  according to the teachings herein. Various exemplary drive mechanisms  1006  are presented below. As with any illustrative or exemplary component presented herein, this is done by way of example only and without intending to be limiting in any manner. 
     In one approach, the drive mechanism  1006  drives all spools simultaneously. However, such configuration is not preferred due to the inertia of so many spools with tape  1007  thereon. Rather, in preferred approaches, the drive mechanism  1006  is configured to drive no more than three tape spool pairs  1004  at a time, and more preferably no more than two tape spool pairs  1004  at a time, and ideally, no more than one tape spool pair  1004  at a time. This reduces the total mass to be driven, thereby saving power due to lower inertia relative to driving all spools  1004   a ,  1004   b  on one side of the apparatus  1000 , improving response time, etc. 
     The drive mechanism  1006  in most approaches drives the spools  1004   a ,  1004   b  of a tape spool pair  1004  independently, as the relative rotational velocity of each spool  1004   a ,  1004   b  varies as tape  1007  moves between the spools  1004   a ,  1004   b  in a given tape spool pair  1004 . Accordingly, the drive mechanism  1006  preferably includes at least two motors  1015  coupled to associated drive components. The motors  1015  may be controlled using similar algorithms as used in known tape drives. 
     Moreover, while in most approaches, the drive components driving the spools  1004   a ,  1004   b  may be of similar or the same type, in other approaches, different drive components may be used together, e.g., one set of spools  1004   a ,  1004   b  may be driven by a common axle  1016 ,  1018  while the cooperating spools  1004   a ,  1004   b  may each be driven by an individual motor  1015 . 
     In the exemplary approach shown in  FIG.  10   , the drive mechanism  1006  rotates the axles  1016 ,  1018  extending through a respective row of spools  1004   a ,  1004   b . As noted above, the axles  1016 ,  1018  may drive all, multiple, or one of the spools  1004   a ,  1004   b  at a time. 
     In one approach, the axles  1016 ,  1018  may be comprised of multiple sections, each section being independently drivable for rotating one or more spools  1004   a ,  1004   b  coupled thereto. For example, each spool may be coupled to a unique axle section. In another aspect, two, three, or more spools  1004   a ,  1004   b  are coupled to a unique axle section. Each axle section may be selectively, independently drivable, e.g., using a clutch, using a motor dedicated to each axle section, by positioning a motor to drive an axle section, etc. 
     A clutch  1020  of known type may be included for engaging each axle  1016 ,  1018  to a selected, respective one (or more) of the spools  1004   a ,  1004   b . Accordingly, when the clutch  1020  is engaged, only the desired spool(s)  1004   a ,  1004   b  rotate with the axle  1016 . In some approaches, a unique clutch  1020  may be provided for each spool  1004   a ,  1004   b . In other approaches, a clutch  1020  may be moved to cause engagement of the axle  1016 ,  1018  with the spool  1004   a ,  1004   b  of interest. 
     In addition, a lock down mechanism of any type, e.g., a brake, a gear, etc. may be engaged with the spools  1004   a ,  1004   b  that are not currently being operated on for preventing rotation thereof. 
       FIG.  12    depicts the apparatus  1000  in accordance with one approach. As an option, the present apparatus  1000  may be implemented in conjunction with features from any other approach listed herein, such as those described with reference to the other FIGS. Of course, however, such apparatus  1000  and others presented herein may be used in various applications and/or in permutations which may or may not be specifically described in the illustrative approaches listed herein. Further, the apparatus  1000  presented herein may be used in any desired environment. 
     Referring to  FIG.  12   , the apparatus  1000  includes a drive mechanism having a plurality of motors  1015 , each motor  1015  being coupled to a respective one of the spools  1004   a ,  1004   b  of the tape spool pairs  1004  at the center thereof. In one aspect, each spool  1004   a ,  1004   b  has a dedicated motor  1015 . In another aspect, one motor  1015  may drive a subset of the spools  1004   a ,  1004   b  together, e.g., two or three adjacent spools  1004   a ,  1004   b.    
       FIG.  13 A  depicts the apparatus  1000  in accordance with one approach. As an option, the present apparatus  1000  may be implemented in conjunction with features from any other approach listed herein, such as those described with reference to the other FIGS. Of course, however, such apparatus  1000  and others presented herein may be used in various applications and/or in permutations which may or may not be specifically described in the illustrative approaches listed herein. Further, the apparatus  1000  presented herein may be used in any desired environment. 
     Referring to  FIG.  13 A , the apparatus  1000  includes a drive mechanism  1006  having a plurality of motors  1015 , each motor  1015  being coupled to a respective one of the spools  1004   a ,  1004   b  of the tape spool pairs  1004 . In one aspect, each spool  1004   a ,  1004   b  has a dedicated motor  1015 . In another aspect, one motor  1015  may drive a subset of the spools  1004   a ,  1004   b  together, e.g., two or three adjacent spools  1004   a ,  1004   b.    
       FIG.  13 B  depicts the apparatus  1000  in accordance with one approach. As an option, the present apparatus  1000  may be implemented in conjunction with features from any other approach listed herein, such as those described with reference to the other FIGS. Of course, however, such apparatus  1000  and others presented herein may be used in various applications and/or in permutations which may or may not be specifically described in the illustrative approaches listed herein. Further, the apparatus  1000  presented herein may be used in any desired environment. 
     Referring to  FIG.  13 B , the apparatus  1000  includes a drive mechanism  1006  having, for each row of spools  1004   a ,  1004   b , a drive wheel  1024  driven by a drive axle  1026 . The drive wheel  1024  may have any type of configuration, such as a toothed wheel (gear), a rubber-edged wheel that engages the spool  1004   a ,  1004   b  via frictional engagement, etc. In one aspect, the drive wheel  1024  is selectively positionable along the drive axle  1026 . A positioner  1028  moves the drive wheel  1024  to align the drive wheel  1024  with the spool  1004   a ,  1004   b  of interest. A belt-driven positioner  1028  having a u-shaped gear engaging piece is shown, though any other type of positioner may be used. 
     As should now be apparent, many other types of drive mechanisms  1006  may be employed in the apparatus  1000  without straying from the spirit and scope of the present invention. 
     The magnetic head  1008  may be of conventional design such as one having reading and/or writing modules, etc. Likewise, additional conventional components for proper head  1008  positioning and operation may be included in the apparatus  1000 , such as coarse and fine actuators, cabling, servo and data processing circuitry, etc. 
     In addition, in various approaches, multiple heads  1008  and associated hardware/circuitry may be present, thereby enabling performance of multiple data operations simultaneously. In one aspect, the number of heads  1008  may be equal to the number of tape spool pairs  1004 , as shown in  FIG.  13 C . In some approaches, the heads may share data channel and/or other electronics. In other approaches, the heads  1008  may have dedicated data channel and/or other electronics. 
     The positioning mechanism  1010  is configured to selectively align the magnetic head  1008  to a selected one of the tape spool pairs  1004  so that data operations may be performed. Any suitable type of positioning mechanism  1010  may be used, including known types of positioning mechanisms  1010  adapted for use with the apparatus  1000  according to the teachings herein. 
     In one exemplary approach, the positioning mechanism  1010  includes a guide of any type along which the magnetic head  1008  is positionable. Exemplary guides include, but are not limited to, a rail along which the magnetic head  1008  slides, a groove along which the magnetic head  1008  slides or rolls, a track along which the magnetic head  1008  slides or rolls, etc. Any type of positioning scheme may be used to move the magnetic head  1008  along the guide. In one approach, a worm screw  1011  is configured to move the magnetic head  1008  along the guide. In another approach, the positioning mechanism  1010  includes a belt coupled to the magnetic head  1008 . Positioning mechanisms  1010  such as those used in inkjet printers to move a print head, e.g., along a guide, may be adapted for use with positioning the magnetic head  1008 , as would become apparent to one skilled in the art upon reading the present disclosure.  FIG.  13 B  depicts a belt-driven positioning mechanism  1010 , for example. 
     As should now be apparent, many other types of positioning mechanisms  1010  may be employed in the apparatus  1000  without straying from the spirit and scope of the present invention. 
     The engagement mechanism  1012  is configured to create a relative movement between the magnetic head  1008  and a magnetic recording tape  1007  of the selected one of the tape spool pairs  1004  for engaging the magnetic recording tape  1007  with the magnetic head  1008 . Any suitable type of engagement mechanism  1012  may be used, including known types of engagement mechanisms  1012  adapted for use with the apparatus  1000  according to the teachings herein. 
       FIGS.  14 A and  14 B  depict the apparatus  1000  in accordance with one approach. As an option, the present apparatus  1000  may be implemented in conjunction with features from any other approach listed herein, such as those described with reference to the other FIGS. Of course, however, such apparatus  1000  and others presented herein may be used in various applications and/or in permutations which may or may not be specifically described in the illustrative approaches listed herein. Further, the apparatus  1000  presented herein may be used in any desired environment. 
     Referring to  FIGS.  14 A and  14 B , the engagement mechanism  1012  is configured to move the magnetic head  1008  toward the magnetic recording tape  1007 . For example, an actuator may be used to translate the magnetic head  1008  into engagement with a tape  1007  extending between the spools  1004   a ,  1004   b.    
       FIGS.  14 C and  14 D  depict the apparatus  1000  in accordance with one approach. As an option, the present apparatus  1000  may be implemented in conjunction with features from any other approach listed herein, such as those described with reference to the other FIGS. Of course, however, such apparatus  1000  and others presented herein may be used in various applications and/or in permutations which may or may not be specifically described in the illustrative approaches listed herein. Further, the apparatus  1000  presented herein may be used in any desired environment. 
     Referring to  FIGS.  14 C and  14 D , the engagement mechanism  1012  is configured to move the magnetic head  1008  toward the magnetic recording tape  1007 . For example, the positioning mechanism  1010  or other mechanisms may be used to pivot the magnetic head  1008  into engagement with a tape  1007  extending between the spools  1004   a ,  1004   b.    
       FIGS.  15 A and  15 B  depict the apparatus  1000  in accordance with one approach. As an option, the present apparatus  1000  may be implemented in conjunction with features from any other approach listed herein, such as those described with reference to the other FIGS. Of course, however, such apparatus  1000  and others presented herein may be used in various applications and/or in permutations which may or may not be specifically described in the illustrative approaches listed herein. Further, the apparatus  1000  presented herein may be used in any desired environment. 
     Referring to  FIGS.  15 A and  15 B , the engagement mechanism  1012  depicted is configured to move the magnetic recording tape  1007  toward the magnetic head  1008  to engage the tape  1007  with the magnetic head  1008 . In the approach shown in the transition from  FIG.  15 A  to  FIG.  15 B , one tape guide is moved from a retracted position ( FIG.  15 A ) to a deployed position ( FIG.  15 B ), thereby lifting the tape  1007  into engagement with the magnetic head  1008 . The retracted position allows the magnetic head  1008  to move past the tape  1007 , e.g., to an adjacent tape  1007 . An actuator may be used to move the tape guide. In another approach, both tape guides may be repositioned. 
     As should now be apparent, many other types of engagement mechanisms  1012  may be employed in the apparatus  1000  without straying from the spirit and scope of the present invention. 
       FIGS.  15 A and  15 B  depict the apparatus  1000  in accordance with one approach. As an option, the present apparatus  1000  may be implemented in conjunction with features from any other approach listed herein, such as those described with reference to the other FIGS. Of course, however, such apparatus  1000  and others presented herein may be used in various applications and/or in permutations which may or may not be specifically described in the illustrative approaches listed herein. Further, the apparatus  1000  presented herein may be used in any desired environment. 
     Referring to  FIGS.  10 - 15 B , apparatus  1000  in accordance with any approach described herein preferably includes a controller  1034  that performs one or more of the following functions: controls operation of one or more of the apparatus components, maintains an index of the data on the tape  1007 , service read requests, selects one of the tapes  1007  for servicing write requests, etc. The controller  1034  may be onboard the apparatus  1000 , external thereto, etc. For example, an onboard controller  1034  may be electrically coupled to each of the various apparatus components and programmed to provide the desired apparatus functionality. 
     The apparatus  1000  and/or controller  1034  may be configured to function with existing storage software, storage controllers, etc. For example, the apparatus  1000  may be configured to appear to a host and/or storage controller as a conventional data storage drive, thereby enabling use of the apparatus  1000  with existing storage software. Known techniques adapted for this purpose may be used. 
     The apparatus  1000  itself may be dimensioned for mounting in a computer rack, or in any other environment, enclosure, etc. 
     An array of apparatuses  1000  may be provided to work in concert, thereby providing a system capable of storing massive quantities of data with seek times rivalling current disk-based data storage systems. Accordingly, such systems incorporating an array of the apparatuses  1000  are usable for cloud storage, enterprise-level storage, etc. One skilled in the art, now armed with the teachings herein, will appreciate that known data storage system control and interface technology may be adapted for use with and/or control of such multi-apparatus systems. 
     Now referring to  FIG.  16   , a flowchart of a method  1600  is shown according to one approach. The method  1600  may be performed in accordance with the present invention in any of the environments depicted in  FIGS.  1 - 15 B , among others, in various approaches. Of course, more or fewer operations than those specifically described in  FIG.  16    may be included in method  1600 , as would be understood by one of skill in the art upon reading the present descriptions. 
     Each of the steps of the method  1600  may be performed by any suitable component of the operating environment. For example, in various approaches, the method  1600  may be partially or entirely performed by apparatus  1000  and/or controller  1034  or some other device having one or more processors therein. The processor, e.g., processing circuit(s), chip(s), and/or module(s) implemented in hardware and/or software, and preferably having at least one hardware component may be utilized in any device to perform one or more steps of the method  1600 . Illustrative processors include, but are not limited to, a central processing unit (CPU), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), etc., combinations thereof, or any other suitable computing device known in the art. 
     As shown in  FIG.  16   , method  1600  includes operation  1602 , in which a positioning mechanism  1010  is instructed to selectively align a magnetic head  1008  to a selected one of a plurality of tape spool pairs  1004  in a receiving area  1002  of an apparatus  1000 . The positioning mechanism  1010  may include any feature described in the exemplary approaches above with reference to  FIGS.  10 - 15 B . 
     In operation  1604 , an engagement mechanism  1012  is instructed to create a relative movement between the magnetic head  1008  and a magnetic recording tape  1007  of the selected one of the tape spool pairs  1004  for engaging the magnetic recording tape  1007  with the magnetic head  1008 . The engagement mechanism  1012  may include any feature described in the exemplary approaches above with reference to  FIGS.  10 - 15 B . 
     In operation  1606 , a drive mechanism  1006  is instructed to drive the selected tape spool pair  1004 . The drive mechanism  1006  may include motors  1015 , e.g., as described in the exemplary approaches above with reference to  FIGS.  10 - 15 B . In one approach, instructing the drive mechanism  1006  to drive the selected tape spool pair  1004  includes instructing a pair of drive motors  1015  coupled to the selected tape spool pair  1004  to drive the selected tape spool pair  1004 . 
     In some aspects, operation  1606  may include causing a clutch  1020  to engage the drive mechanism  1006  to a spool  1004   a ,  1004   b  of the selected tape spool pair  1004 . 
     In operation  1608 , a magnetic head  1008  is caused to perform data operations (e.g., read and/or write) on the magnetic recording tape  1007  of the selected tape spool pair  1004 , e.g., in a similar manner as used in conventional tape drives. 
     Now referring to  FIG.  17   , a flowchart of a method  1700  is shown according to one approach. The method  1700  may be performed in accordance with the present invention in any of the environments depicted in  FIGS.  1 - 16   , among others, in various approaches. Of course, more or fewer operations than those specifically described in  FIG.  17    may be included in method  1700 , as would be understood by one of skill in the art upon reading the present descriptions. 
     Each of the steps of the method  1700  may be performed by any suitable component of the operating environment. For example, in various approaches, the method  1700  may be partially or entirely performed by apparatus  1000  and/or controller  1034  or some other device having one or more processors therein. The processor, e.g., processing circuit(s), chip(s), and/or module(s) implemented in hardware and/or software, and preferably having at least one hardware component may be utilized in any device to perform one or more steps of the method  1700 . Illustrative processors include, but are not limited to, a CPU, an ASIC, a FPGA, etc., combinations thereof, or any other suitable computing device known in the art. 
     In operation  1702 , a drive mechanism  1006  is instructed to drive a selected tape spool pair  1004 . The drive mechanism  1006  may include motors  1015 , clutches, etc. e.g., as described in the exemplary approaches above. 
     In operation  1704 , a magnetic head  1008  is caused to perform data operations (e.g., read and/or write) on the magnetic recording tape  1007  of the selected tape spool pair  1004 , e.g., in a similar manner as used in conventional tape drives. 
     In operation  1706 , the drive mechanism  1006  is instructed to drive a second tape spool pair  1004  for performing a second operation on the second tape spool pair  1004  while the data operations are being performed. The second operation may be any type of operation performed by a conventional tape drive. Examples of second operations include, but are not limited to, tape spool refresh operations in which the tape is transferred at low tension from one spool to the other; seek operations to move the tape of the second tape spool to an approximate position where a read and/or write operation will be performed, etc. 
     Operation  1706  may be performed for multiple tape spool pairs  1004 . 
     Now referring to  FIG.  18   , a flowchart of a method  1800  is shown according to one approach. The method  1800  may be performed in accordance with the present invention in any of the environments depicted in  FIGS.  1 - 17   , among others, in various approaches. Of course, more or fewer operations than those specifically described in  FIG.  18    may be included in method  1800 , as would be understood by one of skill in the art upon reading the present descriptions. 
     Each of the steps of the method  1800  may be performed by any suitable component of the operating environment. For example, in various approaches, the method  1800  may be partially or entirely performed by apparatus  1000  and/or controller  1034  or some other device having one or more processors therein. The processor, e.g., processing circuit(s), chip(s), and/or module(s) implemented in hardware and/or software, and preferably having at least one hardware component may be utilized in any device to perform one or more steps of the method  1800 . Illustrative processors include, but are not limited to, a CPU, an ASIC, a FPGA, etc., combinations thereof, or any other suitable computing device known in the art. 
     In operation  1802 , writing operations are performed on the magnetic recording tape  1007  of a selected tape spool pair  1004 , e.g., in a similar manner as used in conventional tape drives. 
     In operation  1804 , the written data is mirrored to another tape spool pair, thereby providing redundancy. The raw data may be written to the other tape spool pair, and/or any other data that enables redundancy, e.g., parity data, error correction code data, etc. 
     Now referring to  FIG.  19   , a flowchart of a method  1900  is shown according to one approach. The method  1900  may be performed in accordance with the present invention in any of the environments depicted in  FIGS.  1 - 18   , among others, in various approaches. Of course, more or fewer operations than those specifically described in  FIG.  19    may be included in method  1900 , as would be understood by one of skill in the art upon reading the present descriptions. 
     Each of the steps of the method  1900  may be performed by any suitable component of the operating environment. For example, in various approaches, the method  1900  may be partially or entirely performed by apparatus  1000  and/or controller  1034  or some other device having one or more processors therein. The processor, e.g., processing circuit(s), chip(s), and/or module(s) implemented in hardware and/or software, and preferably having at least one hardware component may be utilized in any device to perform one or more steps of the method  1900 . Illustrative processors include, but are not limited to, a CPU, an ASIC, a FPGA, etc., combinations thereof, or any other suitable computing device known in the art. 
     In operation  1902 , a request to read data from a magnetic recording tape  1007  of a first tape spool pair  1004 , is received. In one approach, a copy of the data is also stored (mirrored) on the magnetic recording tape  1007  of a second tape spool pair. In another approach, portions of the requested data are stored across multiple tape spool pairs. 
     In operation  1904 , a portion of the data is read from the selected tape spool pair, e.g., in a similar manner as used in conventional tape drives. 
     In operation  1906 , while operation  1904  is being performed, the magnetic recording tape  1007  of the second tape spool pair is being positioned to an approximate starting position of another portion of the requested data. 
     In operation  1908 , the other portion of the requested data is read from the magnetic recording tape  1007  of the second tape spool pair, e.g., in a similar manner as used in conventional tape drives. Where only one magnetic head is present in the device, the head may be moved to the second tape spool pair to read the data therefrom. 
     This method  1900  provides a speed advantage where the requested data is distributed in portions along a tape, e.g., due to writing in append only mode, as well as spread across multiple tapes. By positioning the magnetic recording tape of the second tape spool pair while the first portion of data is being retrieved, the second portion of the data can be accessed more quickly than, for example, spooling the magnetic recording tape of the first tape spool pair to the approximate location of the next portion of data or waiting to index the second tape spool pair until the head is available. 
     The present invention may be a system, a method, and/or a computer program product at any possible technical detail level of integration. The computer program product may include a computer readable storage medium (or media) having computer readable program instructions thereon for causing a processor to carry out aspects of the present invention. 
     The computer readable storage medium can be a tangible device that can retain and store instructions for use by an instruction execution device. The computer readable storage medium may be, for example, but is not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. A non-exhaustive list of more specific examples of the computer readable storage medium includes the following: a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanically encoded device such as punch-cards or raised structures in a groove having instructions recorded thereon, and any suitable combination of the foregoing. A computer readable storage medium, as used herein, is not to be construed as being transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide or other transmission media (e.g., light pulses passing through a fiber-optic cable), or electrical signals transmitted through a wire. 
     Computer readable program instructions described herein can be downloaded to respective computing/processing devices from a computer readable storage medium or to an external computer or external storage device via a network, for example, the Internet, a local area network, a wide area network and/or a wireless network. The network may comprise copper transmission cables, optical transmission fibers, wireless transmission, routers, firewalls, switches, gateway computers and/or edge servers. A network adapter card or network interface in each computing/processing device receives computer readable program instructions from the network and forwards the computer readable program instructions for storage in a computer readable storage medium within the respective computing/processing device. 
     Computer readable program instructions for carrying out operations of the present invention may be assembler instructions, instruction-set-architecture (ISA) instructions, machine instructions, machine dependent instructions, microcode, firmware instructions, state-setting data, configuration data for integrated circuitry, or either source code or object code written in any combination of one or more programming languages, including an object oriented programming language such as Smalltalk, C++, or the like, and procedural programming languages, such as the “C” programming language or similar programming languages. The computer readable program instructions may execute entirely on the user&#39;s computer, partly on the user&#39;s computer, as a stand-alone software package, partly on the user&#39;s computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user&#39;s computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). In some embodiments, electronic circuitry including, for example, programmable logic circuitry, field-programmable gate arrays (FPGA), or programmable logic arrays (PLA) may execute the computer readable program instructions by utilizing state information of the computer readable program instructions to personalize the electronic circuitry, in order to perform aspects of the present invention. 
     Aspects of the present invention are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer readable program instructions. 
     These computer readable program instructions may be provided to a processor of a computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. These computer readable program instructions may also be stored in a computer readable storage medium that can direct a computer, a programmable data processing apparatus, and/or other devices to function in a particular manner, such that the computer readable storage medium having instructions stored therein comprises an article of manufacture including instructions which implement aspects of the function/act specified in the flowchart and/or block diagram block or blocks. 
     The computer readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other device to produce a computer implemented process, such that the instructions which execute on the computer, other programmable apparatus, or other device implement the functions/acts specified in the flowchart and/or block diagram block or blocks. 
     The flowchart and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the blocks may occur out of the order noted in the Figures. For example, two blocks shown in succession may, in fact, be accomplished as one step, executed concurrently, substantially concurrently, in a partially or wholly temporally overlapping manner, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts or carry out combinations of special purpose hardware and computer instructions. 
     Moreover, a system according to various approaches may include a processor and logic integrated with and/or executable by the processor, the logic being configured to perform one or more of the process steps recited herein. The processor may be of any configuration as described herein, such as a discrete processor or a processing circuit that includes many components such as processing hardware, memory, I/O interfaces, etc. By integrated with, what is meant is that the processor has logic embedded therewith as hardware logic, such as an application specific integrated circuit (ASIC), a FPGA, etc. By executable by the processor, what is meant is that the logic is hardware logic; software logic such as firmware, part of an operating system, part of an application program; etc., or some combination of hardware and software logic that is accessible by the processor and configured to cause the processor to perform some functionality upon execution by the processor. Software logic may be stored on local and/or remote memory of any memory type, as known in the art. Any processor known in the art may be used, such as a software processor module and/or a hardware processor such as an ASIC, a FPGA, a central processing unit (CPU), an integrated circuit (IC), a graphics processing unit (GPU), etc. 
     It will be clear that the various features of the foregoing systems and/or methodologies may be combined in any way, creating a plurality of combinations from the descriptions presented above. 
     It will be further appreciated that aspects of the present invention may be provided in the form of a service deployed on behalf of a customer to offer service on demand. 
     The descriptions of the various aspects of the present invention have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the approaches disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described approaches. The terminology used herein was chosen to best explain the principles of the approaches, the practical application or technical improvement over technologies found in the marketplace, or to enable others of ordinary skill in the art to understand the approaches disclosed herein.