Abstract:
A tape drive assembly for data storage on a magnetic tape includes a tape head, a cartridge receiver and a controller. The cartridge receiver selectively receives a cartridge having a test tape formatted at a predetermined location with standard drive compatible format with increased data redundancy enabling tape drives to read data in the presence of excessive errors in tape drives that exceed the capabilities of the native drive format error corrections code. The test tape is able to operate in a drive, with multiple defective heads, that said drive would not operate with a normal format tape.

Description:
BACKGROUND 
       [0001]    Magnetic storage devices remain a viable solution for the storage and retrieval of large amounts of data. The use of magnetic tape cartridges, e.g., such as half-inch digital linear tape (“DLT”), linear tape open (“LTO”) and helical scan tapes formats, such as 4 mm (“DAT”, “8 mm”) are well known in the art. Tape cartridges can store a vast amount of data. Tape drives can be used either singly as standalone tape drive or in a tape library (also referred to as a media library). 
         [0002]    Generally, each tape drive includes multiple recording and reproducing transducers to write and/or read data to the tape cartridges. Typical modern tape drives use thin film magnetoresistive (MR) head or ferrite core transducers to read and/or writes data to the tape cartridges and are commonly referred to as tape heads. Magnetic storage devices are generally read/write capable and may be erased and written over many times during their lifetime. 
         [0003]    For proper operation of the tape drive and to be able to record and reproduce data from the tape with acceptable data errors, the head must maintain very close proximity to the storage tape of the tape cartridge in order to provide the ability to record and reproduce signals. The head operates in an open environment and can be exposed to various contaminants from the open air and/or from the storage tape itself. Today&#39;s heads require very low separation between the head and the storage tape for greater accuracy in reading and writing of data. Excessive separation between the head and the storage tape and/or sensor damage such as scratches, nicks or other abrasions to the head itself can result in reading and writing errors or even head failure. 
         [0004]    It is well known that tape to head separation increases when contaminants build up on the surface of the head. Cleaning cartridges or brushes can be used to remove contaminants. Unfortunately, these types of cleaning devices can be relatively ineffective for removing hardened deposits on the head. Further, when the sensor of the head is impacted with sufficient force, or when a conductive material causes a short in an element in the head, the head is rendered unusable and the drive must be repaired. In addition, contaminants and tape abrasive materials can generate surface scratches that effectively create permanent separation between the tape and the sensor. These defects will also reduce the head signal, requiring repair to the head. 
         [0005]    Tapes are made of flexible basefilm such as PEN, PET or Poly-Aramid. The basefilm is coated with a very thin magnetic recording layer where the data is recorded. It is also well known that during normal operations, tapes degrade and lose their recording properties with repeated use of the same tape due to surface scratches caused by the running of the tape at close contact with the head. Furthermore, airborne contaminants deposited on the tape can cause tape surface damage such as scratches, nicks or other abrasions. Deposits, contaminants, or abrasions on the tape surface can result in reading and writing errors or even drive failure. It is well known in the art that tape drives dominant failure mode is related to the inability of the drive to write or read data. 
         [0006]    Presently, the drive diagnosis is lengthy, complex and costly. For example, when a tape drive fails within a media library, it is not possible to determine with certainty if the cause of the failure is marginal head or tape as both can produce data errors. In the case where multiple drives record data on the same cartridge, then it is virtually impossible to determine the marginal drive that caused the error, especially when the failure is compounded by a combination of the marginal heads and marginal media. Furthermore, drives that fail due to fatal data write or read errors (hard errors) are no longer capable to operate, therefore it is not possible to perform field testing, as the error often exceeds the ECC capabilities and the drive cannot be initialized in order to further test or repair the drive according to the U.S. application Ser. No. 12/694,977 assigned to George A. Saliba and U.S. Pat. No. 7,583,463 issued to George A. Saliba. 
         [0007]    The current practice in the tape industry is to ship the suspect drives back to the factory for extensive testing where the drives are disassembled and the suspect heads are carefully removed from the drives. Suspect heads are returned to the head vendors for test and possible repair. 
         [0008]    Accordingly, methods and systems to determine with certainty the cause of drive data failures in the field, and the need to eliminate the requirement for the costly and extensive factory diagnosis and associated head removals and tests, are highly desired. 
       SUMMARY 
       [0009]    The present invention is directed toward a tape drive assembly for the storage of magnetic data on a tape cartridge. In one embodiment, the tape drive assembly includes a tape head, a cartridge receiver and a controller. The tape head magnetically interacts with the storage tape. The cartridge receiver selectively receives a cartridge having a test tape having compatible data format with enhanced capabilities to read data in the presence of high data error drives. The enhanced format is accomplished by increasing the number of redundant blocks on the tape above standard format. In this embodiment, the extended format restores the drives ability to transfer data in the presence of severe drive failures (multiple defective channels). The extended redundancy format enables various algorithms to test the drive, determines the head quality and, if necessary, initiates corrective actions such as cleaning requests or head lapping. 
         [0010]    In some embodiments, the controller reserves certain sections of the tape and writes data formatted with predetermine distributions of typical tape error types with varying duration, count and magnitude. 
         [0011]    An embodiment of the present invention is also directed toward one or more methods for testing of the quality of the head of the drive. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The invention, together with further advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying drawings, taken in conjunction with the accompanying description, in which similar reference characters refer to similar parts, and in which: 
           [0013]      FIG. 1  is a block diagram of one embodiment of a media library having features of the present invention including a plurality of tape drives and a plurality of tape cartridges; 
           [0014]      FIG. 2  is a top view of a portion of one embodiment of the tape drive and the tape cartridge; 
           [0015]      FIG. 3  is a tape format with track data redundancy on multiple tracks according to one embodiment of the invention; 
           [0016]      FIG. 4  is a tape format with sequential data redundancy according to one embodiment of the current invention; 
           [0017]      FIG. 5  is a tape format with track data redundancy that repeats down the tracks according to one embodiment of the invention; 
           [0018]      FIG. 6  is a tape format with track data rotation where data redundancy spans across tracks according to one embodiment of the invention; 
           [0019]      FIG. 7  is a tape format data redundancy whereas the redundant data is rotated across multiple tracks and is compatible with standard DLT tape formats; 
           [0020]      FIG. 8  is a tape format data redundancy whereas the redundant data is added to the standard format and rotated across multiple tracks and is compatible with standard LTO formats; 
           [0021]      FIG. 9  is a flow diagram illustrating the tape redundancy formatting method to generate a test tape in accordance with the present invention; 
           [0022]      FIG. 10  is a flow diagram for the test and repair of tape drives using tapes formatted with data redundancy according to the invention. 
       
    
    
     DESCRIPTION 
       [0023]      FIG. 1  is a simplified schematic view of one embodiment of a media library  10 , in the form of a multi-drive, mass storage and retrieval tape library/loader unit. In one embodiment, the media library  10  includes a housing  12 , a power supply  14 , a plurality of drive assembly receivers  18 , a plurality of tape drive assemblies  20 - 1 ,  20 - 2 ,  20 - 3  (also sometimes generically referred to herein as tape drive assemblies  20 ), one or more cartridge retainer receivers  22 , a cartridge mover  24  including a cartridge pass-through and/or rotating elevator  26 , at least one cartridge elevator guide shaft  28 , a drive shaft  30 , a rack drive shaft  32 , a cartridge elevator motor  34 , a pulley drive assembly  36 , a roller drive shaft motor  38  and a rack drive shaft motor  40 . The housing  12  may be constructed of any number and/or type of conventional materials such as, for example, those utilized in industry standard rack mount cabinets. It is recognized that many different suitable types of cartridge movers  24  can be utilized in the media library  10 , and that the cartridge mover  24  provided herein is merely representative of one such type and is not intended to limit the scope of the present invention in any manner. 
         [0024]    In this embodiment, the power supply  14  can provide electrical power to the plurality of drive assembly receivers  18 , one or more of the tape drive assemblies  20 , the cartridge elevator motor  34 , the roller drive shaft motor  38 , and/or the rack drive shaft motor  40 . The power supply  14  is interfaced with these components as well as with an external power source using industry standard cabling and connections (not shown). 
         [0025]    Each of the drive assembly receivers  18  receives one of the tape drive assemblies  20 . As provided herein, each of the tape drive assemblies  20  can include a corresponding tape drive  46 - 1 ,  46 - 2 ,  46 - 3  (i.e. Quantum DLT 2000XT™, DLT4000™, DLT7000™, DLT8000™, DLT VS80™, DLT VS160™, DLT V4™ DLT S4™, SDLT 320™, SDLT 600™, LTO-2™, LTO-2 HH™, LTO-3™, LTO-3 HH™, LTO-4™, LTO-4 HH™, LTO-5™, LTO-5 HH™, LTO-6™, LTO-6™ HH, DAT 72™, DDS-4™, or equivalent, as non-exclusive examples). 
         [0026]    The tape drive assemblies  20 - 1 ,  20 - 2 ,  20 - 3  within the media library  10  can be substantially identical to one another. Alternatively, one or more of the tape drive assemblies  20 - 1 ,  20 - 2 ,  20 - 3  within the media library  10  can be different from the remaining tape drive assemblies  20 - 1 ,  20 - 2 ,  20 - 3  in the media library  10 . The tape drive assemblies  20  include one or more controllers  44  (one controller  44  is illustrated in  FIG. 1 ). In one embodiment, each tape drive assembly  20 - 1 ,  20 - 2 ,  20 - 3  includes a separate controller  44 . Alternatively, the tape drive assemblies  20 - 1 ,  20 - 2 ,  20 - 3  can share a single controller  44 . 
         [0027]    Each tape drive  46 - 1 ,  46 - 2 ,  46 - 3  (generically referred to as tape drive  46 ) includes a cartridge receiver  48 - 1 ,  48 - 2 ,  48 - 3  (generically referred to as receiver  48 ) and a corresponding cartridge sensor  50 - 1 ,  50 - 2 ,  50 - 3  (generically referred to as sensor  50 ) within the cartridge receiver  48 . The cartridge receiver  48  receives one of a plurality of cartridges  54 D,  54 L,  54 C,  54 T,  54 TC,  54 TL,  54 TD (generically referred to as cartridge  54 ), which are adapted for use in the media library  10 . The cartridge sensor  50  can generate a cartridge presence signal when the cartridge  54  is present within the cartridge receiver  48  of the tape drive  46 . This signal from one tape drive  46  can be provided to the controller  44  and/or to another tape drive  46  in the same media library  10  or in a different media library  10 . 
         [0028]    Each of the cartridge retainer receivers  22  can receive a standard cartridge retainer  51 , such as a tape magazine in one non-exclusive example, which includes a plurality of cartridge receivers  52 . The cartridge retainer  51  includes a cartridge presence indicator  56  within each cartridge receiver  52  which indicates the presence and/or absence of a cartridge  54  within the cartridge receiver  52 . 
         [0029]    In the embodiment illustrated in  FIG. 1 , the cartridge mover  24  is positioned within the housing  12  between the plurality of cartridge receivers  52  and the plurality of cartridge retainer receivers  22 . In this manner, the cartridge mover  24  is able to load and unload one of the cartridges  54  to and from all of the tape drives  46  and cartridge retainers  51  within a given media library  10 . Further, the input of one or more cartridges  54  into the cartridge receiver  52  of one or more tape drives  46  can be automated, or it can be manually undertaken by an operator, for example. 
         [0030]    In the embodiment illustrated in  FIG. 1 , the controller  44  is physically positioned remotely from the tape drives  46 . In an alternative embodiment, the controller  44  is incorporated into one or more of the tape drives  46 . For example, the controller  44  can physically reside within or on one or more of the tape drives  46 . 
         [0031]    In one embodiment, the controller  44  can include a standard driver interface unit for receiving digital commands and translating the commands into driving currents, such as step pulses for controlling stepper motors. Further, the controller  44  can include a standard programmable general purpose computer formed on a single plug-in card unit and preferably includes a programmed microprocessor or microcontroller according to the present invention, memory, communication interface, control interface, connectors, etc. The controller  44  can form part or all of the drive circuitry, which can include or comprise a printed circuit board assembly (not shown), in one non-exclusive example. 
         [0032]    The media library  10  can use well-known industry standard cabling and communication protocols between the controller  44  and other components of the media library  10 . Cabling and electrical characteristics including signaling protocols can be generally standardized, and the logical message protocols can be either proprietary or standardized as known to those skilled in the art. 
         [0033]    Additionally, as set forth in greater detail below, the controller  44  can determine whether a problem with one or more tape drives  46  may be occurring. For example, the controller  44  can monitor the reading and/or writing error rate of the tape drive  46  to determine if this error rate is above a predetermined threshold. If so, the controller  44  can take certain steps to mitigate or reduce the error rate, as described below. Alternatively, the controller  44  can on a preset schedule run preventive tests using the cartridge in accordance one or more embodiments described herein. In certain embodiments, the controller can use an algorithm that is based on one or more of the algorithms in accordance one or more embodiments described herein to determine whether corrective action is required for the tape drive, as more fully described below. In an alternative embodiment, 
         [0034]    The types of cartridges  54  in the media library  10  can vary. For example, the cartridges  54  can include one or more data cartridges  54 D, one or more test cartridges  54 T, one or more lapping cartridges  54 L, one or more cleaning cartridges  54 C, one or more combined test and cleaning cartridges  54 TC, one or more combined test and data cartridges  54 TD, and/or one or more combined test and lapping cartridges  54 TL. The data cartridge  54 D includes a magnetic storage tape that is adapted to store data. The test cartridge  54 T includes formatted tape with predetermined errors that is adapted to perform a test operation on of the tape drive  46 . 
         [0035]    Any number of each type of cartridge  54  can be present within the media library  10  to satisfy the design requirements of the media library  10 . In certain embodiments, all seven types of cartridges  54 D,  54 T,  54 L,  54 C,  54 TC,  54 TL,  54 TD are present. Alternatively, one or more of these types of cartridges  54 D,  54 T,  54 L,  54 C,  54 TC,  54 TL,  54 TD may be absent from the media library  10 . Still alternatively, the media library can also include other types of cartridges, such as a combined cartridge  54 TC that includes a cleaning tape for cleaning dust or other particulates from portions of the tape drive  46  and a test tape. Still alternatively, the media library can also include other types of cartridges, such as a combined cartridge  54 TD that includes a data tape and a test tape. Still alternatively, the media library can also include other types of cartridges, such as a combined cartridge  54 TL that includes a lapping tape and a test tape. 
         [0036]    In one embodiment, two or more different types of cartridges  54 D,  54 T,  54 L,  54 C,  54 TC,  54 TL,  54 TD generally have a substantially similar form factor. In another embodiment, the form factor for two or more of the cartridges  54 D,  54 T,  54 L,  54 C,  54 TC,  54 TL,  54 TD can be different. 
         [0037]      FIG. 2  illustrates one embodiment of a cartridge  254  and the tape drive assembly  220 , which includes one tape drive  246 . It is recognized that the tape drive assembly  220  described herein can be part of the media library  10  as illustrated in  FIG. 1 , or the tape drive assembly  220  can be a stand-alone type of assembly. 
         [0038]    In the embodiment illustrated in  FIG. 2 , the tape drive  246  includes a drive housing  258 , a tape head  260 , a take-up reel  262  having a drive leader  264  and a take-up reel hub  266 , a cartridge receiver  268 , a buckler  270  and the controller  244 . In one embodiment, the cartridge  254  includes a cartridge housing  272 , a cartridge reel  274  having a cartridge hub  276  (shown in phantom), a tape  278 , and a cartridge leader  280  having a cartridge buckle component  282 . The buckler  270  secures the drive leader  264  to the cartridge leader  280 . The buckler  270  moves the drive leader  264  relative to the cartridge leader  280  to automatically buckle and/or unbuckle the drive leader  264  to the cartridge leader  280  in ways known to those skilled in the art. Further, the specific type of buckler  270  included in the tape drive assembly  220  can include any type of device that secures the drive leader  264  to the cartridge leader  280 , and can be varied in ways known to those skilled in the art. 
         [0039]    The drive housing  258  retains the various components of the tape drive  246 , including at least the tape head  260  and the cartridge receiver  268 . In the embodiment illustrated in  FIG. 2 , the tape drive  246  further includes a plurality of tape rollers  283  and tape guides  284  which are coupled or directly secured to the drive housing  258 . The tape rollers  283  and tape guides  284  guide the tape  278  along a tape path across the tape head  260  and onto the take-up reel  262 . In one embodiment, the tape drive  246  includes three tape rollers  283  and two tape guides  284 . However, any suitable number of tape rollers  283  and/or tape guides  284  can be included in the tape drive  246 . 
         [0040]    The tape  278  is secured to the cartridge hub  276  on one end and the cartridge leader  280  on the other end. As illustrated in  FIG. 2 , the cartridge  254  includes a single cartridge reel  274 . In an alternate embodiment (not shown), the cartridge  254  can include two or more cartridge reels  274 . 
         [0041]    In this embodiment, the tape drive  246  also includes a take-up reel motor (not shown) that rotates the take-up reel  262 , and a cartridge reel motor (not shown) that rotates the cartridge reel  274 . The rotational force of the take-up reel motor relative to the cartridge reel motor determines the tension of the tape  278  moving across the tape head  260 . In certain embodiments, the controller  244  dynamically controls the rotational force of the take-up reel motor and the cartridge reel motor to dynamically control the tension of the tape  278  relative to the tape head  260 . In alternative embodiments, the tension of the tape  278  can also or alternatively be controlled by the controller  244  in other suitable ways, such as by controlled movement of the tape head  260  toward and/or away from the tape  278 , or vice versa. 
         [0042]    In one embodiment, the tape  278  of one of the cartridges  254  includes a storage tape only, which magnetically stores data in digital form. In another embodiment, the tape  278  of one of the cartridges  254  includes a test tape only, which includes prewritten data formatted with predetermined errors types and magnitudes to test the head and to determine the head quality factor to read the errors. 
         [0043]    In one embodiment, the test tape cartridge  54 T is used for testing purposes in order to determine the performance level of the tape head and its ability to read long errors with predetermined sizes. In an alternative embodiment, the test tape  54 T can be used both for testing the tape drive, for read head quality, as well as for write head quality. The reference drive records redundant data including an error pattern on a predetermined section of the tape. The suspect drive reads the same section and collects the error. The redundant data enables the suspect drive with defective channels to operate by reading data even when the drive experiences multiple non operational channels by recovering data from the remaining operational channels. The amount of redundant data added to the native format determines the number of defective channels that can be defective in a drive and still be able to complete the test. For example, a drive with 8 channels, with 100 percent redundant data, in the absence of other errors, may only require 4 or less defective channels to complete the test. By comparing the ratio between the reference drive error and the suspect drive error of the same section, the read transducer quality of the suspect head can be determined. The reference drive records an error pattern on a predetermined section of the tape including redundant data. The suspect drive reads the same section and collects the error. The suspect drive overwrites the same section and collects the error data count. By comparing the ratio between the reference drive error and the suspect drive error of the same section, the write transducer quality of the suspect head can be determined. 
         [0044]    In an alternative embodiment, the function of test tape  54 T may be combined with data tape  54 D for both testing and storing customer data storage. In an alternative embodiment, the test tape  54 T may be combined with cleaning tape  54 C for both testing the tape drive and for head cleaning in the same cartridge. In an alternative embodiment, the function of test tape  54 T may be combined with lapping tape  54 L for lapping of the head by using a lapping tape in the test cartridge. 
         [0045]    The proportion of the total length of the test tape and data tape, cleaning tape or lapping tape, can vary depending upon the design requirements of the tape drive assembly  20  and/or the media library  10 . In one embodiment, the ratio of test tape to data tape, cleaning tape or lapping tape can be at least approximately 0.01, 0.1, 0.5, 0.75, 0.9, 1.1, 1.25, 1.5, 2.0, 5.0, 10.0 or 100.0. Still alternatively, the ratio can be above or below the foregoing range. 
         [0046]    The specific design of the test tape can vary to suit the design requirements of the tape drive assembly  20  and/or the media library  10 . In one embodiment, the test tape can include an abrasive material such as a 0.1 micron diamond material. In non-exclusive alternative embodiments, the lapping tape can include a 0.5 micron or a 1.0 micron diamond material. Still alternatively, the test tape can incorporate cleaning tape material suitable to provide the requisite cleaning level of the tape head. 
         [0047]    The length of the test tape section can likewise be varied. In one embodiment, the length of the test tape can be approximately 20 feet. Alternatively, the length can be less than or greater than this length. 
         [0048]    In one embodiment, the test tape may be formatted as a dedicated test cartridge specific for testing the tape heads, the amount of redundancy may vary for example from 10% to 1000%. In another embodiment, the test tape may be formatted as a reserved section of the data tape. In another embodiment, the test tape may be spliced together with a cleaning tape in a similar manner that other types of magnetic recording tapes are spliced together, i.e. in a manner known to those skilled in the art. In another embodiment, the test tape may be spliced together with a lapping tape in a similar manner that other types of magnetic recording tapes are spliced together, i.e. in a manner known to those skilled in the art. Further, the storage tape and/or the lapping tape can each be uninterruptedly positioned within the cartridge, or the storage tape and/or the lapping tape can alternate, e.g., be intermittently or alternatingly positioned within the cartridge. 
         [0049]      FIG. 3  is an example of logical tape format excluding media defects. The data redundancy is repeated on multiple tracks. 
         [0050]      FIG. 4  is an example of logical tape format excluding media defects. The data redundancy is repeated down stream and track to track. 
         [0051]      FIG. 5  is a logical data pattern excluding media defects formatted with redundant data sets recorded down stream of the tracks. This method is effective to improve the test ability of drives with fewer channels such as commonly used in helical scan recording. 
         [0052]      FIG. 6  is an alternate data pattern excluding media defects formatted with redundant data. Redundant data is repeated down stream and on alternate tracks. This method is effective to improve the test ability of drives with multiple channels. 
         [0053]      FIG. 7  is a data redundancy format pattern excluding media defects formatted with redundant data sets recorded according to DLT standard data format. This format is compatible with DLT/SDLT tape drives. 
         [0054]      FIG. 8  is a data redundancy format pattern excluding media defects formatted with redundant data sets recorded according to LTO standard data format. This redundant format is compatible with LTO tape drives. 
         [0055]    Alternatively, a combination of the redundant formatted data may be different than that which is illustrated. The cleaning tape may be a relatively abrasive or non-abrasive type of tape, known to those skilled in the art, which may remove dust and or other loose particulates that may be present on the tape head. The cleaning tape may be formed from a material such as that used in LTO Universal Cleaning cartridge, DLT Cleaning Cartridges or DAT Cleaning cartridge. 
         [0056]      FIG. 9  is a flow diagram illustrating one embodiment of a method for formatting the test cartridge with redundant data in accordance with the present invention. 
         [0057]    A modified drive, or a special drive formatter with the ability to write redundant data according to the desired compatible test format, is used to format the desired format cartridge. The process is similar to standard data writing on multiple channels and tape locations. For linear tape, the data must be written in both directions. Typical tape immediate read after write operation insures that the written data is verified for correct recording and media defects are detected and rewritten (skipped). One more read pass is necessary for the tape controller to determine whether the read errors are below the predetermined threshold level. 
         [0058]    The redundant data is then formatted according the invention application Ser. No. 12/694,977 assigned to George A. Saliba. 
         [0059]    It is recognized that the predetermined threshold and redundancy can be included as part of the firmware or drive circuitry of the tape drive and/or media library, or it can be manually input by an operator as required. 
         [0060]    If the predetermined threshold of read errors is exceeded, the tape is not a good candidate for a test tape and is rejected. 
         [0061]    The next step in the formatting process is to seek to a predetermine location on the tape to format the data errors according to the invention. The location is a design parameter, however, it is recognized that the preferred location is near the beginning of the tape in order to minimize the test time. For linear tape drive, such as LTO and DLT, the preferred location is between 10 meters and 1000 meters or within the first half of the first forward track and within the last half of the reverse track. However, it is understood that the format error location may be formatted at any predetermined location on the tape. 
         [0062]    One preferred method to generate the redundant format is to modify the standard drives to repeat writing the standard data format according to one of the methods described in this invention. One preferred method to generate the predetermined error sizes and shapes is to first write data to the tape and skip media defects, then to overwrite the data with a varying error generator signal consisting of a controlled amplitude and shape at the desired location on the tape. Any other suitable methods or external magnetic transducers may be used to generate the magnetic signal to create the desired error patterns. One preferred method is to use the tape drive&#39;s write transducer to create the errors by modifying the standard recording signal shape and process to match the desired error. During the error formatting step using the write transducer, the drive must disable the read after write defect skipping step and preserve the formatted errors so they can be observed during the drive test process. 
         [0063]    The last step in the error formatting process is to measure the errors count and location for each test cartridge as tested by the reference drive. The cartridge error count is recorded and used as a calibration factor for the drive tested using the cartridge as described herein. 
         [0064]      FIG. 10  is a flow diagram illustrating one embodiment of a method for the test of suspect drive using the test cartridge with redundant data in accordance with the present invention. 
         [0065]    In this embodiment, the test cartridge is used to determine the quality of a suspect drive. The process is similar to standard data reading and writing. The controller requests data to be read from a predetermined location. The read and write error rate of the current drive under test are compared with the calibration data stored during the cartridge generation. The suspect drive quality is determined by comparing its ability to recover data when exposed to the various predetermined errors formatted on the test tape. The relative quality of the suspect drive is calculated as the ratio of the error count to the reference drive error count. 
         [0066]    The last step in the test process, the controller may initiate insertion of a cleaning cartridge into the tape drive, and subsequent cleaning of the tape head in an attempt to repair the drive. 
         [0067]    Once cleaning of the tape head has concluded, the controller can initiate reinsertion of the data cartridge test cartridge. The controller may run test tape to determine if they are still above the predetermined threshold. If not, no further corrective action is necessary. However, if the test cartridge limits are determined by the controller to exceed the predetermined threshold, the controller can take the tape drive off-line (such as in a media library setting) and can initiate insertion of a lapping cartridge and a subsequent lapping operation of the tape head. 
         [0068]    Once the lapping operation has concluded, the controller can initiate reinsertion of the data cartridge into the tape drive. The controller can then insert the test tape to determine whether they exceed the predetermined threshold level. If not, no further corrective action is necessary. 
         [0069]    It is to be understood that the test tape is formed by using standard data tape formatted with redundant data and predetermined errors. The invention can be applied as separate test cartridges, on a predetermined segment of standard data tape or in the same cartridge in combination with cleaning tape or lapping tape by using commonly known tape splicing techniques. Furthermore, this test operation can be applied to determine the need and apply remote corrective non-intrusive traditional drive repair such as updating the micro code of the tape drive and any other suitable tape drive settings prior to restoring the tape drive to an on-line status. 
         [0070]    While the particular media library  10  and tape drive assemblies  20  as herein shown and disclosed in detail are fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that they are merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.