Abstract:
A method to write information to a tape storage medium by disposing a tape storage medium in a tape drive apparatus comprising a write head. The method moves the tape storage medium in a first direction, writes data from a buffer to the tape storage medium, and thereby empties the buffer while the tape storage medium is moving in the first direction. The method determines, while the tape storage medium is moving in the first direction, whether to enable a backhitchless write wherein the tape storage medium is not stopped and moved in a second and opposition direction, prior to writing new data to the tape storage medium. By not stopping the movement of the tape storage medium, and by not moving the tape storage medium in a reverse direction to reposition the write head, the method eliminates the time overhead required to stop the tape and reposition the tape head. Applicants&#39; method achieves this time efficiency without adverse impact to the nominal storage capacity of the tape information medium.

Description:
FIELD OF THE INVENTION 
     The invention is directed to a method to write data to a tape storage medium without stopping the tape to reposition a write head between write operations. 
     BACKGROUND OF THE INVENTION 
     It is known in the art to save data in automated data storage libraries comprising a plurality of tape storage media and one or more tape drives. Certain prior art methods are time inefficient when writing a plurality of datasets to a tape storage medium. The prior art methods repetitively employ a “backhitch” method wherein a tape drive moves the tape in a first direction while writing a current dataset, stops the movement of the tape, reverses the movement of the tape to reposition a write head adjacent the end of the current dataset, and then once again moves the tape in the first direction to write a new dataset to the tape storage medium. 
     SUMMARY OF THE INVENTION 
     The invention comprises a method to write information to a tape storage medium, by disposing a tape storage medium in a tape drive apparatus comprising a write head. The method moves the tape storage medium in a first direction, and completes, or exhausts, a current write operation while the tape storage medium is moving in the first direction. The method determines, while the tape storage medium is moving in the first direction, whether to enable a backhitchless write wherein the tape storage medium is not stopped and moved in a second and opposition direction, prior to beginning writing additional data to the tape storage medium. 
     By not stopping the movement of the tape storage medium, and by not moving the tape storage medium in a reverse direction to reposition the write head, Applicants&#39; method eliminates the time overhead required to stop the tape and reposition the tape head. Applicants&#39; method achieves this time efficiency without adverse impact to the nominal storage capacity of the tape information medium. By “without adverse impact to the nominal storage capacity of the tape information medium,” Applicants mean that use of their method does not decrease the nominal storage capacity of the tape information medium. 
     In certain embodiments, the method determines an Expected Capacity On Current Location (S), wherein the value of (S) represents the amount of storage capacity that has already been utilized to complete the current and all subsequent write operations to the tape storage medium. In certain embodiments, the method determines an Actual Capacity On Current Location (R), wherein the value of (R) represents total amount of written data from the beginning of storage capacity to the current location In certain embodiments, based upon the Expected Capacity On Current Location (S), and based upon the Actual Capacity On Current Location (R), the tape drive determines whether to enable a backhitchless write wherein the tape storage medium is not stopped and moved in a second and opposition direction, prior to beginning a new write operation, or resuming a current write operation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be better understood from a reading of the following detailed description taken in conjunction with the drawings in which like reference designators are used to designate like elements, and in which: 
         FIG. 1  is a flow chart summarizing certain of the steps of Applicants&#39; method; 
         FIG. 2  is a block diagram illustrating the longitudinal position of a write head with respect to a tape storage medium upon completion of a current write operation; 
         FIG. 3  is a block diagram illustrating the movement of the tape storage medium of  FIG. 2  when receiving a new write operation; 
         FIG. 4A  is a block diagram illustrating a first step in a prior art backhitch write method; 
         FIG. 4B  is a block diagram illustrating a second step in a prior art backhitch write method; 
         FIG. 4C  is a block diagram illustrating a third step in a prior art backhitch write method; 
         FIG. 4D  is a block diagram illustrating a fourth step in a prior art backhitch write method; 
         FIG. 5  is a block diagram illustrating a first plurality of datasets written to the tape medium of  FIG. 2  in an (i)th write operation and a second plurality of datasets written to the tape medium in an (i+1)th write operation using the prior art method of  FIGS. 4A ,  4 B,  4 C, and  4 D; 
         FIG. 6  is a block diagram illustrating Applicants&#39; backhitchless write method; 
         FIG. 7  is a block diagram illustrating a first plurality of datasets written to the tape medium of  FIG. 2  in an (i)th write operation and a second plurality of datasets written to the tape medium in an (i+1)th write operation using Applicants&#39; backhitchless write method; 
         FIG. 8  is a block diagram illustrating Applicants&#39; tape drive apparatus; 
         FIG. 9A  is a flowchart summarizing steps in one embodiment of Applicants&#39; method; 
         FIG. 9B  is a flowchart summarizing additional steps in one embodiment of Applicants&#39; method; 
         FIG. 10  is a flowchart summarizing additional steps in a second embodiment of Applicants&#39; method; 
         FIG. 11  is a flowchart summarizing additional steps in a third embodiment of Applicants&#39; method; and 
         FIG. 12  is a flowchart summarizing additional steps in a fourth embodiment of Applicants&#39; method. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     This invention is described in preferred embodiments in the following description with reference to the Figures, in which like numbers represent the same or similar elements. Reference throughout this specification to “one embodiment,” “an embodiment,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment. 
     The described features, structures, or characteristics of the invention may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are recited to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention may be practiced without one or more of the specific details, or with other methods, components, materials, and so forth. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention. 
     Referring now to  FIG. 8 , when writing data to a magnetic tape storage medium, such as magnetic tape  200  ( FIGS. 2 ,  3 ,  4 A,  4 B,  4 C,  4 D,  8 ), a portion of the tape medium is disposed on a first rotatable reel, such as reel  802 , and a portion of the tape medium is disposed on a second rotatable reel, such as reel  804 . The rotatable reels are moved such that tape storage medium  200  is moved from one reel, past tape head  810 , and onto to the other reel. Tape head  810  comprises write head  812 , wherein write head  812  encodes information in tape storage medium  200  as that medium travels past write head  812 . As those skilled in the art will appreciate, tape head  810  may comprise other elements and components not shown in  FIG. 8 . 
     In the illustrated embodiment of  FIG. 8 , tape head  810  is in communication with controller  820 . In certain embodiments, controller  820  is integral with tape head  810 . Further in the illustrated embodiment of  FIG. 8 , controller comprises processor  822  and data buffer  824 . Controller  820  is in communication with computer readable medium  830 . Instructions  832  is encoded in computer readable medium  830 . 
     In certain embodiments, computer readable medium  830  is integral with controller  820 . In the illustrated embodiment of  FIG. 8 , reel  802 , reel  804 , tape head  810 , controller  820 , and computer readable medium  830  are disposed within tape drive apparatus  800 . As those skilled in the art will appreciate, tape drive apparatus  800  may comprise other elements and components not shown in  FIG. 8 . 
     Referring now to  FIG. 2 , tape storage medium  200  ( FIGS. 2 ,  3 ,  4 A,  4 B,  4 C,  4 D,  8 ) is moving in direction shown. In the illustrated embodiment of  FIG. 2 , dataset  202  was first written to tape storage medium  200 , then dataset  204  was written to tape storage medium  200 , and finally dataset  206  was written to tape storage medium  200 . Dataset  206  comprises the last, i.e. the (N)th dataset, in a write operation. At time T 0 , the current write operation is complete, and a write head, such as write head  812  ( FIG. 8 ), is longitudinally positioned at location  210  with respect to tape storage medium  200  ( FIGS. 2 ,  3 ,  4 A,  4 B,  4 C,  4 D,  8 ). 
     Referring now to  FIG. 3 , at time T 1 , wherein time T 1  is subsequent to time T 0 , a new write operation is received by a tape drive apparatus, such as tape drive apparatus  800  ( FIG. 8 ), having tape  200  removeably disposed therein. In certain embodiments, the tape drive apparatus receives the new write operation from an interconnected host computer. At time T 1 , the write head is longitudinally positioned at location  310  along tape storage medium  200 . 
       FIGS. 4A ,  4 B,  4 C, and  4 D, illustrate a prior art “backhitch” method the movement of a tape medium in a first direction is stopped because host issues sync command, for example a writefm non-immediate command, to finish the first write operation, the tape medium is then moved in a second and opposite direction, and the tape medium is again stopped such that the write head is positioned adjacent a previously-written dataset received in the current write operation, and the tape medium is again moved in the first direction while writing a new dataset received in a new write operation. Referring now to  FIG. 4A , at time T 2 , wherein time T 2  is subsequent to time T 1 , the tape drive apparatus stops the movement of tape storage medium  200  ( FIGS. 2 ,  3 ,  4 A,  4 B,  4 C,  4 D,  8 ) in preparation for executing the new write operation. Referring now to  FIG. 4B , at time T 3 , wherein time T 3  is subsequent to time T 2 , the tape drive apparatus moves the tape storage medium  200  ( FIGS. 2 ,  3 ,  4 A,  48 ,  4 C,  4 D,  8 ) in a second, and opposite, direction. Referring now to  FIG. 4C , at time T 4 , wherein time T 4  is subsequent to time T 3 , the tape drive apparatus stops the movement of tape storage medium  200  such that the write head is longitudinally positioned at location point  410  along tape storage medium  200 , wherein location  410  is adjacent the end of dataset  206 . Referring now to  FIG. 4D , at time T 5 , wherein time T 5  is subsequent to time T 4 , the tape drive apparatus moves tape storage medium  200  in the first direction, and the write head begins to encode the new dataset into that tape storage medium. 
     The “backhitch” method of  FIGS. 4A ,  4 B,  4 C, and  4 D, requires a backhitch time interval ΔT BACKHITCH  to complete, wherein ΔT BACKHITCH  starts at time T 1 , when a new dataset is received, and ends at time T 5 , when a new dataset is first written to the tape storage medium.  FIG. 5  illustrates encoded tape  500  written using the prior art backhitch method illustrated in  FIGS. 2 ,  3 ,  4 A,  4 B,  4 C, and  4 D. 
     Applicants have found that the backhitch time interval ΔT BACKHITCH  is often as long as about 3 seconds. As those skilled in the art will appreciate, if host issues a total of (M) sync command, and the tape drive uses the prior art backhitch method (M) times, then an overhead equal to [(M)*3] seconds is used to repetitively reposition the write head. In certain embodiments, Applicants&#39; method to write information to a tape storage medium does not utilize the prior art backhitch process. 
     Applicants&#39; method transitions from  FIG. 3  wherein a new dataset is received at time T 1  to  FIG. 6  wherein Applicants&#39; method at time T 1  begins to write that new dataset to the tape storage medium.  FIG. 7  illustrates encoded tape  700  written using Applicants&#39; method illustrated in  FIGS. 2 ,  3 , and  6 . Applicants&#39; method results in a loss of tape storage capacity equal to distance  710  comprising the unused portion of tape  700  disposed between the end of the (N)th dataset in the (i)th write operation and the beginning of the (N+1)th dataset in the (i+1)th write operation. 
     Applicants have found that a tape storage medium actually comprises more storage capacity than its nominal storage capacity. As a general matter, a typical tape storage medium comprises some additional storage capacity (for example, 7% to the nominal capacity). As an example, a 500 gigabyte tape storage medium actually comprises about 535 gigabytes of useable storage capacity. 
     As noted above, use of Applicants&#39; backhitchless write method saves time when drive receives multiple transaction data followed by sync command. Applicants have further discovered that the time advantage realized using their backhitchless write method does not necessarily result in a use of less than the nominal storage capacity of the tape storage medium. Rather, the storage capacity loss resulting from use of Applicants&#39; backhitchless write method only decreases the amount of additional storage capacity that exceeds the nominal storage capacity. 
       FIG. 1  summarizes the steps of Applicants&#39; method. Referring now to  FIG. 1 , in step  110  the method provides a tape drive apparatus, such as tape drive apparatus  800  ( FIG. 8 ), with a tape storage medium, such as tape storage medium  200  ( FIGS. 2 ,  3 ,  4 A,  4 B,  4 C,  4 D,  8 ), removeably disposed therein. In step  120 , the method establishes a Dataset Separation Threshold, wherein that Dataset Separation Threshold is used to determine whether to implement Applicants&#39; backhitchless write method described hereinabove. In certain embodiments, step  120  is performed by the manufacturer of the tape drive apparatus. In certain embodiments, step  120  is performed by the manufacturer of the tape storage medium. In certain embodiments, step  120  is performed by the manufacturer of an automated data storage library comprising the tape drive apparatus. In certain embodiments, step  120  is performed by a host computer in communication with the tape drive apparatus. 
     In step  130 , the method completes or exhausts a current write operation. In certain embodiments, in step  130  a write head disposed in the tape drive apparatus of step  110  completes encoding a current write operation to the tape storage medium of step  102 . In other embodiments, the transfer rate from a data buffer, such as buffer  824  ( FIG. 8 ) to the write head exceeds the transfer rate of data from a host computer to the tape drive, wherein the data buffer is emptied. In these embodiments, a current write operation is not completed, however, that current write operation is temporarily exhausted until additional data is received from the host computer. 
     In step  140 , the method determines whether to enable use of Applicants&#39; backhitchless write method, described hereinabove, when beginning a new write operation, or resuming a current write operation. In certain embodiments, the tape drive apparatus performs step  140 . 
     In certain embodiments, step  140  comprises the steps recited in  FIG. 9 . Referring now to  FIG. 9 , in steps  910  through  935  the method determines an Expected Capacity On Current Location (S), wherein the value of (S) represents the amount of storage capacity that has already been utilized to complete the current and all subsequent write operations to the tape storage medium. In certain embodiments, the tape drive apparatus of step  110  performs steps  910  through  935 , inclusive. In steps  940  through  950 , the method determines an Actual Capacity On Current Location (R), wherein the value of (R) represents total amount of written data from the beginning of storage capacity to the current location. In certain embodiments, the tape drive of step  110  performs steps  940  through  950 , inclusive. 
     If the current write operation and all subsequent write operations to the tape storage medium were performed without any error, and without using any backhitchless writes, then (S) would equal (R). On the other hand and as described hereinabove, each backhitchless write operation results in a storage capacity loss, such as storage capacity loss  710  ( FIG. 7 ). Use of a single backhitchless write operation results in (S) being greater than (R). 
     In step  910  the method determines a nominal storage capacity (C) for the tape storage medium. In certain embodiments, step  910  is performed by a tape drive apparatus. In step  915 , the method determines a longitudinal tape length (L) for the tape storage medium. In certain embodiments, step  915  is performed by a tape drive apparatus. 
     In step  920 , the method determines a current wrap number for the write head. In certain embodiments, step  920  is performed by a tape drive apparatus. As those skilled in the art will appreciate, data is written to a magnetic tape using a plurality of write heads, wherein the tape is first moved in a first direction from the BOT to the EOT while writing a first plurality of data tracks. The direction of the tape is then reversed, and the tape is moved in a second and opposite direction while a second plurality of data tracks are written starting at the EOT and ending at the BOT. The first plurality of data tracks comprise a first “wrap.” The second plurality of data tracks comprise a second “wrap.” A fully encoded tape storage medium comprises a plurality of wraps. 
     In step  925 , the method determines a current longitudinal position for the write head. In certain embodiments, step  925  is performed by a tape drive apparatus. As those skilled in the art will appreciate, in certain embodiments the tape storage medium of step  102  ( FIG. 1 ) is encoded with a plurality of servo bands written along the length (L) of the tape in non-data regions. A plurality of sequential servo patterns disposed in a servo band encode linear position (“LPOS”) information. In certain embodiments, step  925  comprises decoding a plurality of servo patterns to determines the LPOS position of the write head of step  110  ( FIG. 1 ). 
     In step  930 , the method calculates a parameter (X) for the tape head, wherein (X) is set equal to the multiplication product of the Longitudinal Tape Length (L) of step  915  and the Current Wrap Number of step  920 , plus the Current Longitudinal Position of step  925 . In certain embodiments, step  930  is performed by a tape drive apparatus. 
     In step  935 , the method sets the Expected Capacity On Current Location (S) equal to (X/(L)*(Total Wrap Number))*C. In certain embodiments, step  935  is performed by a tape drive apparatus. 
     In step  940 , the method determines a current dataset number (N). In certain embodiments, step  940  is performed by a tape drive apparatus. In step  945 , the method determines a Dataset Size. In certain embodiments, step  945  is performed by a tape drive apparatus. In step  950 , the method calculates an Actual Capacity On Current Location (R) equal to the multiplication product of the current dataset number of step  940  and the dataset size of step  945 . 
     In step  955 , the method establishes a value for Alpha, wherein the parameter Alpha is used to determine whether to implement Applicants&#39; backhitchless write method described hereinabove. In certain embodiments, the method sets Alpha equal to about 5 GB in step  955 . In certain embodiments, step  955  is performed by the manufacturer of the tape drive apparatus. In certain embodiments, step  955  is performed by the manufacturer of the tape storage medium. In certain embodiments, step  955  is performed by the manufacturer of an automated data storage library comprising the tape drive apparatus. In certain embodiments, step  955  is performed by a host computer in communication with the tape drive apparatus. 
     In step  960 , the method establishes a value for Beta, wherein the parameter Beta is used to determine whether to implement Applicants&#39; backhitchless write method described hereinabove. In certain embodiments, the method sets Beta equal to about 1.05 in step  960 . In certain embodiments, step  960  is performed by the manufacturer of the tape drive apparatus. In certain embodiments, step  960  is performed by the manufacturer of the tape storage medium. In certain embodiments, step  960  is performed by the manufacturer of an automated data storage library comprising the tape drive apparatus. In certain embodiments, step  960  is performed by a host computer in communication with the tape drive apparatus. 
     In step  965 , the method determines if (R)−(S)*Beta+Alpha is greater than 0. In certain embodiments, step  965  is performed by the tape drive of step  910 . If the method determines in step  965  that (R)−(S)*Beta+Alpha is greater than 0, then the method transitions to step  980  and enables use of Applicants&#39; backhitchless write method when beginning a new write operation, or resuming a current write operation. Alternatively, if the method determines in step  965  that (R)−(S)*Beta+Alpha is not greater than 0, then the method transitions to step  970  and does not enable use of Applicants&#39; backhitchless write method. 
     The following examples are presented to further illustrate to persons skilled in the art how to use Applicants&#39; method. These examples are not intended as limitations, however, upon the scope of the invention. 
     EXAMPLE I 
     If (R) and (S) both equal 90 Gigabytes (“GB”), and if Alpha is set to 5 GB and Beta is set to 1.05, then [(R)−(S)*Beta+Alpha] equals +0.5 GB, and therefore the method would elect in step  110  to enable a backhitchless write in step  118 . 
     EXAMPLE II 
     If (R) and (S) both equal 200 Gigabytes (“GB”), and if Alpha is set to 5 GB and Beta is set to 1.05, then [(R)−(S)*Beta+Alpha] equals −5 GB, and therefore the method would elect in step  110  not to enable use of Applicants&#39; backhitchless write method. 
     As Examples I and II illustrate, the method of  FIG. 9  enables use of Applicants&#39; backhitchless write method when writing data to a tape storage medium relatively near the beginning of tape (“BOT”), but not near the end of tape (“EOT”). Use of their backhitchless write method near the BOT ensures that most of the additional storage capacity over the nominal storage capacity of the tape medium remains available for use. Therefore, the time advantage realized using Applicants&#39; backhitchless write method does not result in a loss of nominal storage capacity of the information storage medium. On the other hand, use of Applicants&#39; backhitchless write method near the EOT might mean that the time advantage realized could result in a loss of nominal storage capacity. 
     In certain embodiments, step  140  comprises the steps recited in  FIG. 10 . Referring now to  FIG. 10 , in step  1010  the method establishes a Backhitchless Threshold Count comprising a maximum number of permitted backhitchless write operations for the tape storage medium of step  110  ( FIG. 1 ). In certain embodiments, the Backhitchless Threshold Count of step  1010  is established by the manufacturer of the tape storage medium of step  110 . In certain embodiments, the Backhitchless Threshold Count of step  1010  is established by the manufacturer of the tape drive of step  110 . 
     In step  1020 , the method determines an Actual Backhitchless Write Count for the tape storage medium of step  110  comprising the number of backhitchless write operations already performed during the current write operation and all subsequent write operations to the tape storage medium. In certain embodiments, step  1020  is performed by the tape drive of step  110  ( FIG. 1 ). 
     In step  1030 , the method determines if the Actual Backhitchless Write Count of step  1020  is greater than the Backhitchless Threshold Count of step  1020 . If the method determines in step  1030  that the Actual Backhitchless Write Count of step  1020  is greater than the Backhitchless Threshold Count of step  1020 , then the method transitions from step  1030  to step  1040  and does not enable use of Applicants&#39; backhitchless write method when beginning a new write operation, or resuming a current write operation. Alternatively, if the method determines in step  1030  that the Actual Backhitchless Write Count of step  1020  is not greater than the Backhitchless Threshold Count of step  1020 , then the method transitions from step  1030  to step  1050  and enables use of Applicants&#39; backhitchless write method when beginning a new write operation, or resuming a current write operation. 
     In certain embodiments, step  140  ( FIG. 1 ) comprises the steps recited in  FIG. 11 . Referring now to  FIG. 11 , in step  1110  the method establishes an Error Rate Threshold comprising a maximum error rate permitted when using backhitchless write operations for the tape storage medium of step  110  ( FIG. 1 ). In certain embodiments, the Error Rate Threshold of step  1110  is established by the manufacturer of the tape storage medium of step  110 . In certain embodiments, the Error Rate Threshold of step  1110  is established by the manufacturer of the tape drive of step  110 . 
     In step  1120 , the method determines an Actual Error Rate for the tape storage medium of step  110 . In certain embodiments, step  1120  is performed by the tape drive of step  110  ( FIG. 1 ). 
     In step  1130 , the method determines if the Actual Error Rate of step  1120  is greater than the Error Rate Threshold of step  1110 . If the method determines in step  1030  that the Actual Error Rate of step  1120  is greater than the Error Rate Threshold of step  1110 , then the method transitions from step  1130  to step  1140  and does not enable use of Applicants&#39; backhitchless write method when beginning a new write operation, or resuming a current write operation. Alternatively, if the method determines in step  1130  that Actual Error Rate of step  1120  is not greater than the Error Rate Threshold of step  1110 , then the method transitions from step  1130  to step  1150  and enables use of Applicants&#39; backhitchless write method when beginning a new write operation, or resuming a current write operation. 
     In certain embodiments, step  140  ( FIG. 1 ) comprises the steps recited in  FIG. 12 . Referring now to  FIG. 12 , in step  1210  the method establishes a Backhitchless Write Threshold Interval comprising a minimum tape length between allowed backhitchless write operations for the tape storage medium of step  1101  ( FIG. 1 ). In certain embodiments, the Backhitchless Write Threshold Interval of step  1210  is established by the manufacturer of the tape storage medium of step  110 . In certain embodiments, the Backhitchless Write Threshold Interval of step  1210  is established by the manufacturer of the tape drive of step  110 . 
     In step  1220 , the method determines an Actual Backhitchless Write Interval for the tape storage medium of step  110  comprising the actual tape length between the current write head position and the last backhitchless write operation. In certain embodiments, step  1220  is performed by the tape drive of step  110  ( FIG. 1 ). 
     In step  1130 , the method determines if the Actual Backhitchless Write Interval of step  1220  is greater than the Backhitchless Write Threshold Interval of step  1210 . If the method determines in step  1030  that the Actual Backhitchless Write Interval of step  1220  is not greater than the Backhitchless Write Threshold Interval of step  1210 , then the method transitions from step  1230  to step  1240  and does not enable use of Applicants&#39; backhitchless write method when beginning a new write operation, or resuming a current write operation. Alternatively, if the method determines in step  1230  that the Actual Backhitchless Write Interval of step  1220  is greater than the Backhitchless Write Threshold Interval of step  1210 , then the method transitions from step  1230  to step  1250  and enables use of Applicants&#39; backhitchless write method when beginning a new write operation, or resuming a current write operation. 
     Referring once again to  FIG. 1 , in step  150  the method begins receiving a new write operation or resumes receiving data comprising a current write operation, and begins writing a that newly-received data to a data buffer, such as buffer  824  ( FIG. 8 ), in the tape drive apparatus. In certain embodiments, step  150  is performed by a tape drive apparatus. 
     In step  160 , the method determines if sufficient new data has been received to begin a new write operation, or resume a current write operation. In certain embodiments, step  160  is performed by a tape drive apparatus. If the method determines in step  160  that insufficient new data has been received to begin a new write operation, or to resume a current write operation, then the method pauses at step  160  while receiving additional new data. 
     If the method determines in step  160  that sufficient new data has been received to begin a new write operation, or to resume a current write operation, then the method transitions from step  160  to step  170  wherein the method determines if a backhitchless write is enabled. In certain embodiments, step  170  is performed by a tape drive apparatus. 
     If the method determines in step  170  that a backhitchless write is enabled in step  140  then the method transitions from step  170  to step  175  wherein the method determines the Actual Distance between the write head and the end of the last previously-written data. In certain embodiments, step  175  is performed by a tape drive apparatus. In step  180 , the method determines if the Actual Distance determined in step  175  is greater than the Dataset Separation Threshold of step  120 . In certain embodiments, step  180  is performed by a tape drive apparatus. 
     If the method determines in step  180  that the Actual Distance determined in step  175  is greater than the Dataset Separation Threshold of step  120 , then the method transitions from step  180  to step  185  wherein the method backhitches the tape storage medium. In certain embodiments, step  185  is performed by a tape drive apparatus. By “backhitches the tape storage medium,” Applicants mean the method implements the tape movement shown and described in  FIGS. 4A ,  4 B,  4 C, and  4 D. The method transitions from step  185  to step  190  wherein the method begins writing the new data to the tape storage medium. In certain embodiments, step  190  is performed by a tape drive apparatus. 
     If the method determines in step  180  that the Actual Distance determined in step  175  is not greater than the Dataset Separation Threshold of step  120 , then the method transitions from step  180  to step  190  and using Applicants&#39; backhitchless write method begins writing the new data to the tape storage medium. 
     If the method determines in step  170  that a backhitchless write is not enabled then the method transitions from step  170  to step  185  and continues as described herein. 
     In certain embodiments, individual steps recited in  FIGS. 1 ,  9 ,  10 ,  11 , and/or  12 , may be combined, eliminated, or reordered. 
     In certain embodiments, Applicants&#39; invention includes instructions, such as instructions  832  ( FIG. 8 ), residing in computer readable medium, such as for example computer readable medium  830  ( FIG. 8 ), wherein those instructions are executed by a processor, such as processor  822  ( FIG. 8 ), to perform one or more of steps  130 ,  140 ,  150 ,  160 ,  170 ,  175 ,  180 ,  185 , and/or  190 , recited in  FIG. 1 , and/or one or more of steps  910 ,  915 ,  920 ,  925 ,  930 ,  935 ,  940 ,  045 ,  950 ,  955 ,  960 ,  965 ,  970  and/or  980 , recited in  FIG. 9 , and/or one or more of steps  1010 ,  1020 ,  1030 ,  1040 , and/or  1050 , recited in  FIG. 10 , and/or one or more of steps  1110 ,  1120 ,  1130 ,  1140 , and/or  1150 , recited in  FIG. 11 , and/or one or more of steps  1210 ,  1220 ,  1230 ,  1240 , and/or  1250 , recited in  FIG. 12 . 
     In other embodiments, Applicants&#39; invention includes instructions residing in any other computer program product, where those instructions are executed by a computing device external to, or internal to, tape drive apparatus  800  ( FIG. 8 ), to perform one or more of steps  130 ,  140 ,  150 ,  160 ,  170 ,  175 ,  180 ,  185 , and/or  190 , recited in  FIG. 1 , and/or one or more of steps  910 ,  915 ,  920 ,  925 ,  930 ,  935 ,  940 ,  045 ,  950 ,  955 ,  960 ,  965 ,  970  and/or  980 , recited in  FIG. 9 , and/or one or more of steps  1010 ,  1020 ,  1030 ,  1040 , and/or  1050 , recited in  FIG. 10 , and/or one or more of steps  1110 ,  1120 ,  1130 ,  1140 , and/or  1150 , recited in  FIG. 11 , and/or one or more of steps  1210 ,  1220 ,  1230 ,  1240 , and/or  1250 , recited in  FIG. 12 . In either case, the instructions may be encoded in computer readable medium comprising, for example, a magnetic information storage medium, an optical information storage medium, an electronic information storage medium, and the like. By “electronic storage media,” Applicants mean, for example and without limitation, one or more devices, such as and without limitation, a PROM, EPROM, EEPROM, Flash PROM, compactflash, smartmedia, and the like. 
     While the preferred embodiments of the present invention have been illustrated in detail, it should be apparent that modifications and adaptations to those embodiments may occur to one skilled in the art without departing from the scope of the present invention as set forth in the following claims.