Abstract:
An apparatus and method are disclosed to read from a portable data storage cartridge data position information, and to communicate that data position information to a data drive unit during transport of the cartridge to that data drive unit.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to a data storage and retrieval system, and in particular to a data storage and retrieval system utilizing portable data storage cartridges, each of which includes data position information stored within a memory device, in combination with memory reading devices disposed on one or more accessors movably disposed within that data storage and retrieval system. The present invention further relates to a method to communicate such position information relating to a specified portable data storage cartridge to a data drive in advance of the arrival of that specified portable data storage cartridge to expedite data acquisition from that specified portable data storage cartridge. 
     BACKGROUND OF THE INVENTION 
     The need to store and retrieve large volumes of digital data has resulted in the need for data storage devices having ever increasing amounts of storage capacity. Data can be stored, of course, in cassettes, floppy disks, diskettes, hard disks, optical disks, capacitative disks and the like. However, the greater the amount of memory available, the more difficult it becomes to accurately obtain specified data with rapid access times and with maximum system fault tolerance. 
     Automated data storage and retrieval systems, more commonly known as libraries, jukeboxes or auto changers (collectively referred to herein as “libraries”), are frequently used when there is a need to keep relatively large amounts of data available at a cost per gigabyte which is lower than that of solid state memory or hard files. Libraries are available for optical disks, optical tape and magnetic tape media. The optical disks can be, for example, rewritable magneto-optical, rewritable phase change, write-once (WORM), standard CD-ROM, recordable CD-ROM, erasable CD-ROM or high density CD-ROM. Magnetic tape, optical tape, and optical disks (one or more), are often disposed within a rigid protective housing comprising a cassette or a cartridge. Some libraries store and transport “magazines” containing several media-containing cartridges. As used herein, unless otherwise specified, the term “media” will refer to any data storage media by itself, and the term “cartridge” will refer to any portable data storage device having a data storage media internally disposed therein. 
     Prior art systems sometimes utilize a plurality of data storage media in conjunction with one or more robotic accessors to retrieve stored cassettes and place them in data drive unit. For example, portable data storage cartridges are transported from a storage area to a data drive mechanism which reads and/or records data for utilization by a host computer from and/or to the data storage media disposed within those cartridges. After the data drive unit, and its associated drive controller, have completed use of the data storage media, the portable data storage cartridge is returned to its storage area. The time expended to transport the cartridge from the storage area to the data drive mechanism is lost in prior art system because the cartridge is transported with very little, if any, retrieval of the data position information from the media disposed in the cassette. 
     A typical library contains one or more banks, columns, or walls of storage cells, one or more data drive units, and one or more accessors to transport specified portable data storage cartridges between those storage cells and data drives. Each accessor generally includes a hand-like gripper mechanism to remove and/or insert the portable data storage cartridges to and from a storage cell, and to and from a data drive unit. The library may also include an input/output station through which an operator can insert or withdraw data units into and from the interior of the library. 
     The components of a library are coupled to and controlled by a library controller which in turn is coupled to a host computer. Data requests are exchanged between the host computer and the library controller, and between the library controller and the other components of the library system. Data written on, or retrieved from, storage media disposed in portable cassettes is exchanged between the host computer and the drive controller. 
     In many prior art libraries, the cassettes (cartridges) have a machine readable label on a front facing edge which is visible when the cartridge is in a storage cell. A reader, such as a vision system or bar code scanner is mounted on the accessor. The reader senses the label to verify that a particular cartridge is the cartridge which has been specified. Such a system is shown in U.S. Pat. No. 5,729,464, issued on Mar. 17, 1998 to K. E. Dimitri, entitled “Media Identification In An Automated Data Library,” and assigned to the assignee of the present invention. Only a very limited amount of data, however, can be retrieved from such a label. In addition, that limited information is not changeable unless the entire label is replaced. 
     What is needed is an apparatus and a method to enable a data storage and retrieval system to obtain data position information from a specified portable data storage cartridge, and to provide that data position information to a data drive unit before arrival of that specified data storage device, i.e. while an accessor is transporting that portable data storage cartridge to the drive. 
     SUMMARY OF THE INVENTION 
     Applicants&#39; invention includes a portable data storage cartridge which includes a memory device disposed therein and data position information stored on that memory device. Applicants&#39; invention further includes an accessor for retrieving and transporting Applicants&#39; portable data storage cartridge within a data storage and retrieval system. Applicants&#39; accessor includes one or more gripper mechanisms and a memory reading device disposed thereon such that when one of Applicants&#39; portable data storage cartridges is releaseably attached to any of the gripper mechanisms the accessor&#39;s memory reading device is disposed adjacent the cartridge&#39;s memory device. 
     Applicants&#39; invention further includes a method to expedite access to data stored on a data storage media disposed within Applicants&#39; portable data storage cartridge. Applicants&#39; invention further includes a computer useable medium having computer readable program code disposed therein to implement Applicants&#39; method to expedite data retrieval from a portable data storage cartridge. 
     The foregoing and other features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of one embodiment of Applicants&#39; data storage and retrieval system; 
     FIG. 2 is a perspective illustration of Applicants&#39; robotic accessor moveably disposed within Applicants&#39; data storage and retrieval system; 
     FIG. 3A is a perspective view of a tape cartridge constructed in accordance with a preferred embodiment of the present invention particularly illustrating the arrangement of respective components in the cartridge; 
     FIG. 3B shows the top half of Applicants&#39; portable data storage cartridge; 
     FIG. 3C shows the bottom half of Applicants&#39; portable data storage cartridge; 
     FIG. 4 is a plan view of the corner of Applicants&#39; cartridge of FIG. 3A, including the memory storage device of the present invention; 
     FIG. 5 is a block diagram depicting the components of one embodiment of Applicants&#39; data storage and retrieval system; 
     FIG. 6 is a block diagram depicting the components of a second embodiment of Applicants&#39; data storage and retrieval system; 
     FIG. 7A is a flow chart summarizing the initial steps in Applicants&#39; method to expedite access to data stored on data storage media disposed within Applicants&#39; portable data storage cartridges; 
     FIG. 7B is a flow chart summarizing additional steps in Applicants&#39; method to expedite access to data stored on data storage media disposed within Applicants&#39; portable data storage cartridges; and 
     FIG. 8 is a schematic illustrating a contactless interface between a memory device and a memory reading device. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to the illustrations, like numerals correspond to like parts depicted in the figures. The invention will be described as embodied in an automated data storage and retrieval subsystem for use in a data processing environment. Although certain of the embodiments shown use magnetic tape cartridges, one skilled in the art will recognize that the invention equally applies to optical disk cartridges or other removable storage media. Furthermore, the description of a data storage and retrieval system is not meant to limit Applicants&#39; invention to only data processing applications, as the invention herein can be applied to portable data storage cartridge handling systems in general. 
     Referring to FIG. 1, Applicants&#39; automated data storage and retrieval system  100  is shown having a first wall of storage slots  102  and a second wall of storage slots  104 . Portable data storage cartridges are individually stored in these storage slots. Such portable data storage cartridges comprise a data storage media disposed within a portable container, i.e. a cartridge. Examples of such data storage media include magnetic tapes, optical disks of various types, including ROM, WORM, and rewritable, and the like. 
     Applicants&#39; automated data storage and retrieval system includes one or more accessors, such as accessors  110  and  120 . An accessor is a robotic device which accesses portable data storage media from first storage wall  102  or second storage wall  104 , delivers that accessed media to data storage drives  130 / 140  for reading and/or writing data thereon, and returns the media to the proper storage slot. 
     As shown in FIG. 1, accessors  110  and  120  travel bi-directionally along rail  170  in an aisle disposed between first wall of storage slots  102  and second wall of storage slots  104 . Library controller  160  controls the operations of accessors  110 / 120  and data storage drives  130 / 140 . Library controller  160  includes at least one computing processor. In the embodiment shown in FIG. 1, library controller  160  is disposed within system  100 . In alternative embodiments, library controller  160  is located external to system  100 . In these remote controller embodiments, library controller  160  communicates with system  100  via a communication link (not shown in FIG.  1 ). 
     In certain embodiments, library controller  160  is in communication with host computer  560  (FIGS. 5,  6 ) from which library controller  160  receives instructions. In certain embodiments, data to be recorded onto, or read from, a selected portable data storage cartridge is communicated between the drive  130 / 140  and host computer  560  either via library controller  160 . In alternative embodiments, data to be recorded onto, or read from, a selected portable data storage cartridge is communicated directly between drive  130 / 140  and host computer  560 . 
     Operator input station  150  permits an operator to communicate with Applicants&#39; automated data storage and retrieval system  100 . Power component  180  and power component  190  each comprise one or more power supply units which supply power to the individual components disposed within Applicants&#39; automated data storage and retrieval system. 
     Import/export station  172  include access door  174  pivotably attached to the side of system  100 . Portable data storage cartridges can be placed in the system, or in the alternative, removed from the system, via station  172 /access door  174 . 
     Referring to FIG. 2, accessor  110  travels bi-directionally along rail system  170 . In the embodiment shown in FIG. 2, rail system  170  comprises two parallel rails. Accessor  110  includes vertical pillar  210 . Lifting servo section  220  moves vertically along pillar  210 . Accessor  110  includes first gripper mechanism  230 , second gripper mechanism  240 , and memory reading device  250 . 
     In accord with Applicants&#39; invention, one or more portable data storage cartridges disposed within system  100  includes memory device  400  (FIG. 4) containing data position information. This data position information is somewhat akin to a file allocation table (“FAT”) sometimes used on computer disks, where that FAT contains information regarding the location of data on those disks. Similarly, the data position information stored in the memory device  400  comprises information regarding the location of data stored on data storage media  350  (not shown in FIGS.) internally disposed within cartridge  300  (FIG.  3 ). Cartridge  300  is shown in greater detail in FIGS. 3A,  3 B, and  3 C. 
     Referring now to FIG. 3A, cartridge  300  is shown comprising housing  310 . Housing  310  includes top surface  312 , bottom surface  314 , first side  316  and opposing second side  318 , third side  320  and opposing fourth side  322 . Data storage media  350  (not shown in FIG. 3) is internally disposed within housing  310 . There are various features not shown on housing  310 , such as locating notches, write-inhibiting switches, and the like, which are not relevant to the present invention. It is apparent to those skilled in the art that tape cartridge  300  is only exemplary and the present invention is applicable to any configuration of tape cartridge  300 . 
     Referring to FIGS. 3B and 3C, housing  310  can be formed from top half  330  and bottom half  340 . Top half  330  and bottom half  340  can be formed by, for example, casting, molding, stamping, or milling any rigid material, including metal, plastic, and combinations thereof. In the alternative, housing  310  can be formed from individual components  312 ,  314 ,  316 ,  318 ,  320 , and  322 , wherein those individual components are formed using the methods recited above, and joined using conventional techniques such as welding, adhesive bonding, mechanical attachment, including screws, nuts, bolts, and the like. In one embodiment, housing  310  is formed by injection molding top half  330  and bottom half  340 , inserting data storage media  350  and memory device  400  into bottom half  340 , and then joining top half  330  to bottom half  340 . 
     In one embodiment of Applicants&#39; invention, data storage media  350  comprises a single reel tape (not shown in FIGS. 3A,  3 B,  3 C) for an automatic threading tape drive. The reel includes layers of magnetic tape with a leader block attached to the free end of the tape. This leader block is held in a receiving well disposed on one corner of the cartridge when the cartridge is out of the tape drive. The leader block connects with a threading pin in the threading tape drive (not shown) for threading the tape through the drive to a take-up reel hub. The leader block includes a conforming section that fits the leader block into a channel of the tape drive. U.S. Pat. No. 4,426,047, issued on Jan. 17, 1984, and assigned to the assignee of the present invention, includes a more complete description of such tape cartridge with a leader block and a tape drive, and is hereby incorporated by reference. 
     FIG. 4 shows memory device  400  disposed within side  320  of cartridge  300 . In the embodiment shown in FIG. 4, memory device  400  is internally disposed within housing  310  such that side  410  of memory device  400  is flush with side  320  of cartridge  300 . Memory device  400  is disposed within housing  310  such that memory device  400  can communicate with memory reading device  250  (FIG. 2) disposed on accessors  110 / 120  (FIG.  1 ). In certain embodiments, memory device  400  comprises a non-volatile memory device. In certain embodiments of Applicants&#39; invention, memory device  400  comprises a non-volatile, semiconductor memory device. 
     Memory device  400  need store only a limited amount of data, that is, data sufficient for library controller  160  (FIG. 1) to ascertain the location of certain requested data on data storage media  350 . In one embodiment, memory device  400  includes Dallas semiconductor DE PROM DS2433. This memory is an electrically erasable and programmable read only memory. In an alternate embodiment, memory device includes a semiconductor memory sold in commerce under the trademark INTRL Strata Flash. 
     FIG. 5 comprises a schematic illustrating, among other things, lifting servo section  220  (FIG. 2) and the positions of memory reading device  250  (FIG. 2) and memory device  400  (FIG. 4) when cartridge  300  (FIG. 3) is removeably attached to either gripper mechanism  230  (FIG. 2) or gripper mechanism  240  (FIG.  2 ). As shown in FIG. 5, when portable data storage cartridge  300  is removeably attached to either gripper mechanism  230  or  240 , memory device  400  is disposed adjacent memory reading device  250 , such that memory reading device  250  can read the information stored in memory device  400 . In one embodiment, memory device  400  includes one or more input/output terminals  412  (not shown in FIG. 4) disposed on side  410  (FIG.  3 ). In this embodiment, memory reading device  250  releaseably connects to those input/output terminals thereby allowing the transfer of information. U.S. Pat. No. 5,606,467 describes such an interconnection between input/output terminals connected to a memory device and a memory reading device, and is hereby incorporated by reference. 
     In alternative embodiments, information is passed from memory device  400  to memory reading device  250  using a contactless interface. In certain embodiments, such a contactless interface comprises a contactless radio frequency interface. In certain embodiments, this radio frequency interface provides power to memory device  400 , and provides read/write access to memory device  400 . In these embodiments, memory device  400  comprises an EEPROM containing 4,096 bytes organized as 128 32-byte accessible blocks. In these embodiments, reading device  250  generates an operating field. This operating field supplies power to memory device  400 , and is modulated by both memory device  400  and memory reading device  250  to enable contactless communication between device  250  and device  400 . 
     In one embodiment, the operating field has a frequency of about 13,560 kHz±7 kHz. The minimum field strength is about 5 A/m and the maximum field strength is about 15 A/m. Memory reading device  250  communicates with memory device  400  by amplitude modulating this operating field. Memory device  400  communicates with memory reading device  250  by load modulating the operating field with a subcarrier having a subcarrier frequency equal to about fc/16. As those skilled in the art will appreciate, load modulation is the process of amplitude modulating a radio frequency field by varying the properties of a resonant circuit placed within the radio frequency field. 
     Referring to FIG. 8, in one embodiment memory device  400  includes circuit  810 . Memory reading device  250  includes circuit  820 . A resistive load is switched in coil  812 . Coil  812  is inductively coupled to coil  822  across contactless interface  830 . Coil  822  generates a radio frequency field at the operating frequency of about 13.56 MHz. The switching amplitude of coil  812  modulates the radio frequency field in coil  822  with a signal, for example, having a frequency of about fc/16, thereby allowing memory device  400  to communicate information to memory reading device  250  across contactless interface  830 . 
     In the embodiment shown in FIG. 5, accessor control card  510  is disposed on lifting servo section  220 . In certain embodiments, accessor control card  510  includes memory  512 . Communication link  520  connects the accessor control card  510  and library controller  160 . Communication link  530  connects memory reading device  250  and accessor control card  510 . Communication link  570  connects library controller  160  and host computer  560 . 
     Data drive  130  (FIG. 1) includes data drive controller  550 . Communication link  540  connects library controller  160  and data drive controller  550 . Data drive  130  includes a read/write head  560  (not shown in FIG. 5) to read data from, and write data to, data storage media  350  resident in a portable data storage cartridge  300  (FIG. 3) when cartridge  300  is disposed in data drive  130 . 
     In certain embodiments, communication links  520 ,  530 , and  540  comprise an ethernet protocol bus or a CANbus protocol bus. Those skilled in the art will appreciate that CANbus technology was developed in the automotive industry, but now has gained wide acceptance in other industries. In these CANbus embodiments, communication links  520 ,  530 , and  540  include 1 Mbit/s transmissions up to 40 meter bus length and 5 Kbit/s transmissions up to 1000 meter bus length. 
     In certain embodiments, communication link  570  is selected from the group comprising a serial interface, such as an RS-232 cable or an RS-422 cable, a SCSI interface, a Fibre Channel interface, a local area network, a private wide area network, a public wide area network, and combinations thereof. 
     Gripper mechanisms  230 / 240  (FIG. 2) position cartridge  300  (FIG. 3) such that memory device  400  is disposed adjacent memory reading device  250  (FIG.  2 ). Memory reading device  250  reads the data position information stored in memory device  400 , and provides that data position information to library controller  160  via communication link  530 , accessor control card  510 , and communication link  520 . Library controller  160  then compares that data position information with the requested data in order to determine the location of that requested data on storage media  350  disposed within the portable data storage cartridge  300 . Library controller  160  in turn provides drive controller  550  with exact position information regarding the location of the requested data on data storage media  350 . 
     With respect to a tape media, after cartridge  300  has been delivered to, and placed in, data drive  130 , drive controller  550  utilizes the exact position information to cause data drive  130  to rapidly advance the tape media with respect to read/write head  560  such that the requested data is quickly available to library controller  160  and host computer  560 . After data retrieval is completed, and in the event no new data is written to data storage media  350 , library controller  160  instructs accessor  110  (FIG. 1) to remove cartridge  300  (FIG. 3) from data drive  130  (FIG.  1 ), and to return portable data storage cartridge  300  to its storage slot in first storage wall  102  (FIG. 1) or second storage wall  104  (FIG.  1 ). 
     Alternatively, if the location of existing data has been changed, or if new data is written to data storage media  350 , the data position information stored in memory device  400  must be updated. In certain embodiments, drive  130  can communicate with memory device  400 . In these embodiments, library controller  160  instructs drive  130 , via drive controller  550 , to update the data position information stored in memory device  400 . 
     In alternative embodiments, drive controller  550  provides library controller  160  with updated data position information. Library controller  160  then communicates this updated information to memory reading device  250  and causes memory reading device  250  to communicate this updated information to memory device  150  for storage therein. 
     Thus, the data position information resident in memory device  400  remains updated with respect to the position of all the data stored on data storage media  350 . In certain embodiments of Applicants&#39; invention, data drive controller  550  or library controller  160  causes data drive  130  or memory reading device  250 , respectively, to overwrite the initial data position information with the updated data position information. 
     FIG. 6 shows an alternative embodiment wherein library controller  160  includes wireless communication device  610 . In the embodiment shown in FIG. 6, wireless communication device  610  includes antenna  620 . In alternate embodiments, wireless communication device  610  does not include antenna  620 . 
     Wireless communication device  630  is disposed on lifting servo section  220  and is connected to accessor control card  510  via communication link  650 . In certain embodiments, communication link  650  comprises an ethernet protocol bus and/or a CANbus protocol bus. In the embodiment shown in FIG. 6, communication device  630  includes antenna  640 . In alternate embodiments, wireless communication device  630  does not include antenna  640 . 
     In Applicants&#39; wireless communication embodiments, accessor  110 , including memory reading device  250 , communicates with library controller  160  by wireless communication. Wireless communication in these embodiments is conducted using emissions in the infrared spectrum, visible spectrum, and/or frequencies between about 10 MHz to about 10 GHz. 
     FIG. 7A is a flowchart summarizing the initial steps in Applicants&#39; method to expedite data retrieval from portable data storage cartridge  300  (FIG.  3 ). In step  702 , host computer  560  (FIGS. 5,  6 ) signals the library controller  160  (FIGS. 1,  5 ,  6 ) to retrieve portable data storage cartridge  300  (FIG. 3) from its storage slot disposed in either first storage wall  102  (FIG. 1) or second storage wall  104  (FIG.  1 ). In step  704 , library controller  160  dispatches accessor  110  (FIGS. 1,  2 ), via accessor control card  510  (FIGS. 5,  6 ), to retrieve cartridge  300 . 
     In step  706 , gripper mechanism  230  (FIG. 2) or gripper mechanism  240  (FIG. 3) holds the cartridge  300  such that memory device  400  (FIG. 4) is disposed adjacent memory reading device  250  (FIG.  2 ). In step  708 , memory reading device  250  reads the data position information stored in memory device  400 . In certain embodiments, this data position information is stored in memory  512  (FIGS. 5,  6 ) disposed on accessor control card  510  (FIGS. 5,  6 ). In step  710  memory reading device  250  provides the downloaded data position information to data drive controller  550  via communication links  520 / 530 / 540 , accessor control card  510 , and library controller  160 . Thus, the data position information downloaded from memory device  400  is provided to data drive controller  550  while accessor  110  is still enroute data drive  130  with portable data storage cartridge  300 . 
     In step  712 , accessor  110  delivers the portable data storage cartridge  300  to data drive  130 . Cartridge  300  is inserted into data drive  130 , and in step  714  data drive controller  550  instructs data drive  130  to quickly advance data storage media  350  such that read/write head  560  is positioned to retrieve the requested data from data storage media  350 . Read/write head  560  then reads the requested data from data storage media  350  and communicates that data to host computer  560  (FIGS. 5,  6 ) via data drive controller  550  (FIGS. 5,  6 ), library controller  160 , communication links  540 / 570  (FIGS. 5,  6 ). In the event no new data is written to data storage media  350 , then in step  718  cartridge  300  is removed from data drive  130  and is returned to storage. 
     Referring now to FIG. 7B, in the event data is written to the data storage media  350 , and in the event data drive  130  can communicate with memory device  250 , then in step  722  data drive  130  provides updated data position information to memory device  400  for storage therein. In the event data drive  130  cannot communicate with memory device  400 , then accessor  110  retrieves cartridge  300  from data drive  130 . In step  726  data drive controller  550  provides updated data position information to library controller  160 . In step  728 , library controller  160  provides that updated data position information to memory reading device  250 . In step  730  memory reading device  250  provides the updated data storage information to memory device  400  for storage therein. Thereafter, portable data storage cartridge  300  is returned to storage within data storage and retrieval system  100 . 
     Applicants&#39; automated data storage and retrieval system includes a computer useable medium having computer readable program code disposed therein to implement Applicants&#39; method to expedite data retrieval from a portable data storage cartridge. The programming of the present invention may comprise a computer program product embodied as program code stored in a storage device, such as a magnetic disk drive or memory, etc., in a computer, or may comprise an article of manufacture, such as a CD ROM, magnetic tape, etc. 
     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. For example, there will be immediately obvious to those skilled in the art, many modifications of structure, arrangement, proportions, elements, materials and components used in the practice of the invention. For instance, there are other types of cartridges and cassettes that could be used with the invention such as, reel-reel cartridges. Also the invention should not be limited to magnetic tapes and drives. It should be obvious that other storage media, including optical media, is equally adaptable to this invention. The appended claims are, therefore, intended to cover and embrace any such modifications, within the true spirit and scope of the invention.