JP2004355747A - Magnetic tape and high-speed data search method of driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten data access waiting time (processing interrupt time of a system) caused by tape feed time for a magnetic tape to make access to a data storage area where the data is stored, when making access to the data stored in an arbitrary position of a cartridge tape of a sequential accessing system. <P>SOLUTION: When the cartridge tape is loaded on a tape driving device, the tape driving device is brought into a ready state after the tape has been fed up to an intermediate position of the effective storage area of the data, and an average data access time is shortened when making access to the data stored in an arbitrary position of the magnetic tape from a host device. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a system used for data backup or data archiving for secondary storage of data and the like stored in a magnetic disk device of a computer, particularly when data is read from a magnetic tape as a portable medium. The present invention also relates to a method for shortening a data access time from when a tape is fed to a tape position where data to be read is recorded and when reading of target data is started.
[0002]
[Prior art]
Generally, data in a computer system is held or stored in a memory, a magnetic disk, or a magnetic tape in order of access frequency. For example, data currently used by a program is read into a memory for use, and data not currently used is stored in a non-volatile magnetic disk device having a high access speed. In general, magnetic disk drives have high performance and reliability, but the cost per fixed data capacity is high, and data that is accessed infrequently is stored on a lower-cost magnetic tape. Read it into the device and use it from the application program. This method is called an archive method. Usually, data stored on a magnetic tape is deleted from a magnetic disk, and when a program needs this data, it is necessary to read the data from the magnetic tape to a magnetic disk device. The archive is a form widely used for retaining data that is not normally accessed but needs to be stored, for example, for the purpose of storing past records of e-mail for a long period of time.
[0003]
Also, unlike archives, a method in which a copy of important data is stored in a secondary storage device such as a magnetic tape in the event of an unexpected failure of the magnetic disk, etc., is called backup, and important data such as a data center is stored in a backup system. Is widely adopted as a method for protecting a computer.
[0004]
As a magnetic tape widely used for the above-mentioned backup application, for example, there is a Linear-Tape Open (hereinafter abbreviated as LTO) which is an industry standard. The outline of the LTO standard is described in a white paper "LTO Tape Has It All: Reliability, Scalability, Performance, and Openness" (published in December 2001) issued by Aberdeen Group, USA.
[0005]
Further, as a magnetic tape widely used for both the backup use and the archive use, there is Digital Data Storage (hereinafter abbreviated as DDS). The DDS standard is standardized by the American National Standards Organization (ANSI). For example, the recording format of a DDS tape is specified by the ANSI X3.203-1992 standard.
[0006]
[Non-patent document 1]
White paper “LTO Tape Has It All: Reliability, Scalability, Performance, and Openness” issued by Aberdeen Group, USA (published in December 2001)
[0007]
[Problems to be solved by the invention]
By the way, when reading data stored in the LTO or DDS standard tape medium, the following preparation work is required. First, the tape cartridge is set in the tape drive device, the magnetic tape is pulled out from the tape cartridge, and the recording surface is brought into close contact with the magnetic head so that the information recorded on the magnetic tape can be read from the magnetic head. At this time, a method of closely contacting the magnetic head with the recording surface of the magnetic tape, a method of reading magnetic data, and the like are specified in detail by the above-described standard of the magnetic tape.
[0008]
Next, in order to read the target data, it is necessary to physically send the tape to the portion of the magnetic tape where the data is recorded, and to prepare the head so that the recording data can be read from the portion of the tape. There is. Generally, a magnetic tape is called a serial access method, and in order to read data recorded at an arbitrary position, it is necessary to physically send a magnetic tape medium as in the above operation. The time required for this tape feeding is a major factor that determines the time required to read data from the tape medium (hereinafter abbreviated as data access time).
[0009]
At present, a magnetic tape widely used is generally in the form of a cartridge tape in which a magnetic tape having a length of several tens of meters to several hundreds of meters is wound on a reel and stored in a cartridge. The LTO standard is a single reel system in which only one of the reels is stored in a tape cartridge, and the DDS standard employs a dual reel system in which two reels, a feed reel and a take-up reel, are stored in a cartridge. Have been. In either the single reel system or the dual reel system, it is necessary to physically send the tape to read magnetic data stored at an arbitrary position as described above, and the time is several seconds. It takes several tens of seconds. During the waiting time for the tape feed, there is a problem that the computer system cannot access the data and the processing must be interrupted. With the recent high performance of computer systems, it has been required to shorten the data access time of a magnetic tape.
[0010]
Here, with reference to FIGS. 8 and 9, a problem in the above-described conventional tape data access will be described. In FIG. 8, when accessing data 206 stored on the magnetic tape 200, the magnetic head 111 needs to be moved to the position of the data 206 because magnetic data is read via the magnetic head 111. However, the actual cartridge tape has a length of several tens to several hundreds of meters. Usually, the tape is fed by winding the tape on a reel as shown in FIG. To be accessible. Due to such a method, the time of tape feeding becomes the waiting time of data access. Normally, the magnetic head 111 starts data access from the SOT 201 which is the start end of the data area of the tape, and feeds the tape to the EOT 202 which is the end end of the data area while sequentially accessing data on the magnetic tape. For this reason, it is good if the data to be accessed is near the SOT 201, but if it is near the EOT 202, the data cannot be accessed while the tape drive performs tape feeding. There was a problem that becomes longer.
[0011]
It is an object of the present invention to reduce the data access time for accessing magnetic data stored in any part of a tape in a magnetic tape and tape drive using a single reel or dual reel cartridge tape, and It is to provide the method.
[0012]
Another object of the present invention is to provide a tape control method for accessing a tape portion storing magnetic data that was accessed last in a magnetic tape and a tape drive using a single-reel or dual-reel type cartridge tape. .
[0013]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, a winding amount detecting means for detecting the winding amount of the tape of the cartridge tape loaded in the tape drive device as length information of the tape is provided. Length information of a data area in which valid data is stored is detected by the winding amount detecting means, and the detected length information of the data area is stored in a storage means incorporated in a cartridge tape. It is.
[0014]
Further, in the present invention, every time the cartridge tape is mounted on the tape drive, the length information of the data area held in the storage means is read out, and the tape feed mechanism provided in the tape drive is used to read the length of the cartridge tape. A tape feeding operation of the magnetic tape is performed, and the tape is fed by a half of the tape length calculated from the length information of the data area, and the magnetic head of the tape drive device is moved to the middle of the data area of the magnetic tape. It is located at a point.
[0015]
Further, in order to achieve the above object, the present invention provides a winding amount detecting means for detecting the winding amount of the tape of the cartridge tape loaded in the tape drive device as information on the length of the tape. The position information at the end of the data area in which valid data is stored is detected by the winding amount detection means, and the position information at the end of the detected data area is stored in the storage means incorporated in the cartridge tape. It is intended to be.
[0016]
Further, in the present invention, every time a cartridge tape is mounted on the tape drive, the last position information of the data area held in the storage means is read out, and the cartridge is moved by a tape feed mechanism provided in the tape drive. A tape feed operation of the magnetic tape of the tape is performed, and the tape is fed by the length of the tape length calculated from the position information at the end of the data area. It is located on the tail.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0018]
FIG. 1 is a diagram showing a first embodiment of the present invention. In FIG. 1, a cartridge tape 110 is composed of a feed reel 113, a take-up reel 114, and an RF memory 115 having a non-contact RF interface, and a magnetic tape 116 wound around the feed reel 113 is a guide roller 112a. And 112b to be taken up on the take-up reel 114. The tape feeding operation of the cartridge tape 110 is performed by mounting the cartridge tape 110 in the tape drive device 101 and operating the drive-side feed motor 120 and the take-up motor 130 of the tape drive device 101. The drive-side feed motor 120 and the take-up motor 130 are controlled by the drive-side motor control unit 104. The RF memory 115 is a rewritable memory having a non-contact interface, and the memory read / write control unit of the tape drive 101 reads and writes data via the RF I / F 106 which is a non-contact interface. Do. To read and write data from the cartridge tape 110, the magnetic head 111 reads magnetic data from the magnetic tape 116, and the data control unit 103 converts the magnetic data into a data format that can be transferred to the host. Transfer with the host via. The data control unit 103 has a read amplifier and a write amplifier for reading and writing signals from the magnetic head 111, a buffer memory for storing data transferred from the host interface 102, an error correction function, and the like. Since it does not relate to the essence of the present invention, a detailed description is omitted.
[0019]
The reel rotation number detection unit 105 detects the rotation numbers of the transmission side reel 113 and the winding side reel 114 by the transmission side sensor 121 and the winding side sensor 131, and detects the detected transmission side reel 113 and the winding side reel 114. Is calculated as a winding amount of the magnetic tape 116 by the tape winding amount calculation unit 107.
[0020]
The feed sensor 121 and the take-up sensor 131 may detect the number of rotations of the drive-side feed motor 120 and the take-up motor 130, and may detect the rotation of the feed side reel 113 and the take-up reel 114 by an optical sensor. May be detected. A method of detecting the number of rotations of a reel by an optical sensor is described in, for example, Japanese Patent Application Laid-Open No. Hei 5-174549, “Method of Detecting Position of Tape Player”.
[0021]
Next, the magnetic tape according to the present embodiment will be described with reference to FIG. In the magnetic tape 116 shown in FIG. 2, the SOT 201 indicates the start end of the area of the tape where magnetic data can be recorded, and the EOT 202 indicates the end end. In the magnetic tape, the data storage area 203 is an area where valid data is written, and the unused area 204 is an area where data can be written. The data area midpoint 205 indicates the midpoint of the tape length of the data storage area 203. The length of the data storage area 203 varies according to the amount of data written on the magnetic tape 116, and similarly the midpoint 205 of the data area varies.
[0022]
Next, the operation of the first embodiment of the present invention shown in FIGS. 1 and 2 will be described with reference to the flowcharts shown in FIGS. First, in the flowchart of FIG. 3, the initialization operation when the cartridge tape 110 is mounted on the tape drive device 101 in the first embodiment of the present invention shown in FIGS. 1 and 2 will be described. In the flowchart of FIG. 3, first, the power of the tape drive 101 is turned on (301), and it is determined whether or not the cartridge tape 110 is mounted on the tape drive 101 (302). The determination of the mounting of the cartridge tape may be performed by providing an optical sensor in the tape drive device 101 or by detecting the RF 115 by the RF I / F 106. When the cartridge tape 110 is mounted, the memory read / write control unit 108 stores the magnetic tape 116 stored in the RF memory 115 of the cartridge tape 110 via the RF I / F 106 which is a non-contact interface of the tape drive device 101. The length information data of the data storage area 203 is read (303). At this time, it is determined from the length information data whether the data storage area 203 is a blank tape having a length of 0 (304). When the tape is a blank tape, the drive motor control unit 104 controls the drive side feed motor 120 and the winding motor so that the magnetic head 111 of the tape drive device 101 is located at the SOT 201 which is the start end of the magnetic tape 116. The feeding motor 130 is controlled to perform the feeding operation of the magnetic tape 116 (305). At this time, the drive motor control unit 104 sequentially reads the data at the leading end of the magnetic tape 116 from the magnetic head 111 by the data control unit 103 and detects the SOT 201 of the magnetic tape 116 at the time of detecting the SOT 201 of the magnetic tape 116. Is performed so as to stop the tape. The format of the magnetic tape such as the SOT 201 is described in, for example, Japanese Patent Application Laid-Open Publication No. 2003-22503, “Data Recording Member and Formatting Method”. In the blank tape determination operation (304), when the length information data of the data storage area 203 of the magnetic tape 116 read from the RF memory 115 of the cartridge tape 110 is not 0, the tape winding amount The calculating unit calculates position information of the data area midpoint 205 of the magnetic tape 116 from the length information data, and further calculates length information from the SOT 201 to the data area midpoint 205 (306). The drive motor control unit 104 of the tape drive device 101 performs a feeding operation of the magnetic tape 116 so that the magnetic head 111 is located at a data area middle point 205 of the magnetic tape 116. At this time, the reel rotation number detection unit 105 detects the rotation number of the transmission side reel 113 and the winding side reel 114 by the transmission side sensor 121 and the winding side sensor 131, and detects the detected transmission side reel. The number of rotations of the take-up reel 113 and the take-up reel 114 is calculated by the tape take-up amount calculation unit 107 as the take-up length of the magnetic tape 116. The drive-side motor control unit 104 performs the tape feeding operation such that the winding length of the magnetic tape 116 matches the calculated length from the SOT 201 to the midpoint 205 of the data area (307). When the above-described magnetic tape feeding operation is completed, the tape drive device 101 enters the ready state and notifies the host device via the host interface 102 that it is ready (308). Data can be transmitted to and received from the host device.
[0023]
Next, the operation of the first embodiment of the present invention shown in FIGS. 1 and 2 when data is written from the host device will be described with reference to FIG. First. When a data write request and write data are transferred from the host device via the host interface 102 (901), the data control unit converts the transferred data into a format writable on the magnetic tape 116, and outputs error correction information. Then, data writing to the magnetic tape 116 via the magnetic head 111 is started (902). Next, the reel rotation number detection unit 105 detects the rotation numbers of the transmission side reel 113 and the winding side reel 114 by the transmission side sensor 121 and the winding side sensor 131 (903). The number of revolutions of the take-up reel 114 is calculated as the winding length of the magnetic tape 116 by the tape winding amount calculation unit 107 (904). When the data writing operation to the magnetic tape is completed (905), the memory read / write control unit 108 reads the data from the magnetic tape 116 stored in the RF memory 115 of the cartridge memory 110 via the RF I / F-106. The length information of the data storage area 203 in which valid data is recorded is read (906). From the length information of the data storage area 203 read by the tape winding amount calculation unit and the calculated winding length of the magnetic tape 116 of the write data, the data storage area 203 after the data writing is obtained. Is calculated as length information from the SOT-201 (907), and written to the RF memory (908) (908). Thereafter, the magnetic tape 116 is fed by the same operation as in steps 306 and 307 of the flowchart shown in FIG. 3 so that the magnetic head 111 is located at the middle point of the data storage area 203 (909). Finally, the host device is notified of the ready state via the host interface 102 (910), and the data writing process is completed.
[0024]
FIG. 4 shows a second embodiment of the present invention. In FIG. 4, a data / servo information separation unit 140 separates servo information and data information previously written on the magnetic tape 116 at predetermined intervals from magnetic data information read from the magnetic tape 116 by the magnetic head 111. The tape position information detector 141 detects the tape position information of the magnetic tape 116 based on the separated servo information. The tape winding amount calculation unit 107 calculates the winding amount of the magnetic tape 116 from the tape position information detected by the tape position information detection unit 141. The first embodiment shown in FIG. 1 controls the tape feeding operation by detecting the number of rotations of the feed-side reel 113 and the take-up reel 114 of the cartridge tape 110 and calculating the tape winding amount. On the other hand, in the present embodiment, the tape winding amount is calculated by using the servo information recorded on the magnetic tape 116 in advance, and the tape feeding operation is controlled. The other operation of the second embodiment of the present invention shown in FIG. 4 is the same as that of the first embodiment of the present invention shown in FIG.
[0025]
Next, FIG. 5 shows a format of a magnetic tape according to a second embodiment of the present invention. In the magnetic tape 116 shown in FIG. 5, servo data 210 is written in advance at regular intervals, and data areas 1-203a, 2-203b, and 3-203c are arranged between the servo data 210 in this order. The format is the same up to the end EOT-202.
[0026]
Next, the positional relationship between the magnetic head 111 and the magnetic tape 116 in the first and second embodiments of the present invention will be described with reference to FIGS. As described above, in the first and second embodiments of the present invention, the data area middle point 205 which is the middle point of the data storage area 203 of the magnetic tape 116 is calculated, and the magnetic head 111 moves to the middle point of the magnetic tape 116. Is controlled to be located at
[0027]
Further, in the above embodiment, the magnetic head is located at an intermediate point of the data storage area 203 using the length information of the data storage area 203 of the magnetic tape 116 stored in the RF memory 115 of the cartridge memory 110. Although the tape feeding operation is performed as described above, the tape feeding operation may be controlled so that the magnetic head 111 is located at the end of the data storage area.
[0028]
Further, in the above-described first and second embodiments of the present invention, after the host system accesses data at an arbitrary location on the magnetic tape, and the data transfer process is completed, the magnetic head 111 returns to the The tape feeding operation may be controlled so as to be located at an intermediate point of the data storage area 203 of the magnetic tape 116.
[0029]
In the first and second embodiments of the present invention described above, the operation is performed using a cartridge tape called a dual reel system or a dual hub system in which both a feed reel and a take-up reel are provided inside the cartridge tape. As described above, the present invention may be configured using a single-reel type or single-hub type cartridge tape having only a feed-side reel. In that case, the tape drive device 101 may be provided with the take-up reel 114 in the first and second embodiments of the present invention.
[0030]
【The invention's effect】
As described above, according to the present invention, when the cartridge tape is mounted on the tape drive, the initialization operation is performed so that the magnetic head is located at the intermediate point of the data storage area of the magnetic tape. When the apparatus accesses data at an arbitrary position on the magnetic tape, there is an effect that the average waiting time for performing the tape feeding operation so that the magnetic head is located at the position of the data can be reduced.
[0031]
Further, according to the present invention, when the cartridge tape is mounted on the tape drive, the initialization operation is performed so that the magnetic head is located at the end of the data storage area of the magnetic tape. When writing data to the empty area of the magnetic tape, there is an effect that the waiting time when performing the tape feeding operation so that the magnetic head is positioned at the head of the write area of the magnetic tape can be reduced.
[0032]
Furthermore, the shortening of the data access time of the magnetic tape has the advantage that the waiting time and the processing interruption time of the host device are reduced, and the processing performance of the computer system is improved.
[Brief description of the drawings]
FIG. 1 is a configuration diagram illustrating an entire configuration of a first embodiment of the present invention.
FIG. 2 is a diagram illustrating a state of use of the magnetic tape according to the first embodiment of the present invention.
FIG. 3 is a flowchart illustrating an initialization operation according to the first embodiment of the present invention.
FIG. 4 is a configuration diagram illustrating an entire configuration of a second embodiment of the present invention.
FIG. 5 is a diagram showing a format of a magnetic tape according to a second embodiment of the present invention.
FIG. 6 is a diagram illustrating a magnetic head position according to the first and second embodiments of the present invention.
FIG. 7 is a diagram showing a magnetic head position according to the first and second embodiments of the present invention.
FIG. 8 is a diagram illustrating a positional relationship between a magnetic tape and a magnetic head according to a conventional example.
FIG. 9 is a diagram illustrating a positional relationship between a magnetic tape and a magnetic head according to a conventional example.
FIG. 10 is a flowchart illustrating an operation when data is written from a host device in the first embodiment of the present invention.
[Explanation of symbols]
101: Tape drive device, 102: Host interface, 103: Data control unit, 104: Drive side motor control unit, 105: Reel rotation speed detection unit, 106: RF I / F (non-contact memory interface), 107: Tape winding Take-off amount calculation unit, 108: memory read / write control unit, 110: cartridge tape, 111: magnetic head, 112a: guide roller, 112b: guide roller, 113: feed reel, 114: take-up reel, 115: RF Memory (non-contact memory), 116: magnetic tape, 120: drive side feed motor, 121: feed side sensor, 130: winding motor, 131: winding side sensor, 130: tape library device, 131: magnetic tape B, 132: Magnetic tape A, 140: Data Servo information separation unit, 141: tape position information detection unit, 201: SOT (start end), 202: EOT (end end), 203: data storage area, 203a: data storage area 1, 203b: data storage area 2, 203c: data storage area 3, 204: unused area, 205: midpoint of data area, 206: target data area.

Claims (7)

A cartridge tape having storage means capable of accessing data by a non-contact interface, and a feeding reel for storing a magnetic tape and a winding reel for winding the tape;
A magnetic head that reads and writes data from a magnetic tape surface of a cartridge tape, a unit that performs data control, a unit that controls a feed-side reel and a take-up reel of the cartridge tape to perform a tape feeding operation, and the cartridge. Means for detecting a winding amount of the magnetic tape of the tape on the winding side reel, a host interface for communicating with a host device, a non-contact interface and a memory capable of accessing data in a storage means of the cartridge memory A tape drive system having read / write means;
Reading the information on the tape length of the data storage area stored in the storage means when the cartridge tape is mounted on the tape drive device;
Calculating a tape winding amount from the information on the tape length of the read data storage area to an arbitrary position in the data storage area where valid data of the magnetic tape of the cartridge tape is recorded;
According to the calculated tape winding amount to an arbitrary position in the data storage area, the tape feeding operation is performed by controlling the feed side reel and the winding side reel of the cartridge tape, and the magnetic head of the tape drive device Controlling the cartridge tape to be located at an arbitrary position in the calculated data storage area;
After the magnetic head is located at the arbitrary position on the cartridge tape, the host device notifies the host device via the host interface of the tape drive device that the tape drive device is in a standby state or ready state. And a high-speed data search method for a magnetic tape and a tape drive device. 2. The high-speed data search method for a magnetic tape and a tape drive device according to claim 1, wherein the arbitrary location of the data storage area is an intermediate point of the data storage area where valid data is stored. 2. The high-speed data search method for a magnetic tape and a tape drive device according to claim 1, wherein the arbitrary location of the data storage area is an end point of the data storage area where valid data is stored. The cartridge tape according to claim 1, wherein the cartridge tape is a single-reel type tape cartridge including only a feed reel that stores a magnetic tape, and a take-up reel for winding the magnetic tape is provided on the tape drive side. A high-speed data search method for a magnetic tape and a tape drive device. A cartridge tape having storage means capable of accessing data by a non-contact interface, and a feeding reel for storing a magnetic tape and a winding reel for winding the tape;
A magnetic head that reads and writes data from a magnetic tape surface of a cartridge tape, a unit that performs data control, a unit that controls a feed-side reel and a take-up reel of the cartridge tape to perform a tape feeding operation, and the cartridge. Means for detecting a winding amount of the magnetic tape of the tape on the winding side reel, a host interface for communicating with a host device, a non-contact interface and a memory capable of accessing data in a storage means of the cartridge memory A tape drive system having read / write means;
When the data transferred from the host interface is written to the cartridge tape, information on a tape length of a data storage area of the magnetic tape where the transferred data is recorded is stored in the storage unit of the cartridge tape. Steps and
Calculating a tape winding amount from the information on the tape length of the stored data storage area to an arbitrary position in the data storage area where valid data of the magnetic tape of the cartridge tape is recorded;
According to the calculated tape winding amount to an arbitrary position in the data storage area, the tape feeding operation is performed by controlling the feeding reel and the winding reel of the cartridge tape. Controlling the cartridge tape to be located at an arbitrary position in the calculated data storage area;
After the magnetic head is located at the arbitrary position on the cartridge tape, the host device notifies the host device via the host interface of the tape drive device that the tape drive device is in a standby state or ready state. And a high-speed data search method for a magnetic tape and a tape drive device. 6. The magnetic tape and tape drive device according to claim 5, wherein the arbitrary location of the data storage area according to claim 5 is a middle point of the data storage area where valid data is stored. High-speed data search method. 6. The magnetic tape and tape drive device according to claim 5, wherein the arbitrary location of the data storage area according to claim 5 is an end point of the data storage area where valid data is stored. High-speed data search method.

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