JP2008010051A - Magnetic tape device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that data is not reproduced by error correction processing and retry processing when a magnetic head is soiled temporarily by being stuck with dust or the like or when a magnetic tape is damaged. <P>SOLUTION: When data is written in a magnetic tape 2, data is duplexed by writing the same data in two portions. When the data is duplexed and written, information that the data has been duplexed is written in a non-contact type memory 3 by a sensor part 7 provide in an RF interface 6. When the data is read from the magnetic tape 2, the recorded content of the non-contact type memory 3 is read by a sensor part 8 to confirm that a data duplex writing flag is on. When the flag is on, the duplexed and written data is read. In this case, when only one of the duplexed data is read, another data is read and transferred to a system device 9. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a magnetic tape device, and more particularly to a method for writing and reading data.

  As a backup device for a server system, a cartridge type magnetic tape device capable of high-capacity and high speed access is used. As a recording system of the cartridge type magnetic tape apparatus, a sequential recording system that performs linear recording with respect to the traveling direction of the magnetic tape is employed. As the capacity of the server system is increased, backup processing or restoration processing to the magnetic tape device is taking a long time, and re-execution due to failure of the backup processing or restoration processing becomes difficult. In Patent Document 1, an error correction code is added to data to restore the error without retrying the error, and a data buffer is provided by providing a first data buffer and a second data buffer. A technique is disclosed that enables streaming running while error correction is performed without stopping tape running for error correction calculation processing by reducing access to.

JP-A-3-283007

  If an error occurs during data reproduction on the magnetic tape, it may be recovered by error correction processing or read retry processing. However, if the magnetic head is temporarily contaminated with dust or the like, or the magnetic tape is scratched. If this occurs, data may not be reproduced by error correction processing or read retry processing. In addition, the read retry process causes a reduction in processing speed because it is necessary to read out again after rewinding the magnetic tape to a portion where reading could not be performed and performing alignment.

  An object of the present invention is to provide a magnetic tape device that suppresses a decrease in processing speed during data reproduction.

In the magnetic tape device of the present invention for writing and reading data to and from a magnetic tape cartridge containing a magnetic tape and a non-contact type memory,
A plurality of magnetic heads comprising a write head and a read head;
A sensor unit for writing management information of the magnetic tape to the non-contact type memory;
A control unit for controlling the plurality of magnetic heads and the sensor unit,
Under the control of the control unit, information indicating that the same data is written twice on the magnetic tape using two of the plurality of magnetic heads, and information is written on the magnetic tape. Writing to the non-contact type memory.
The double writing is preferably performed in parallel with the traveling direction of the magnetic tape.
When the double-written data is read using the magnetic head and it is detected that a write error has occurred from the read data, the magnetic head of the plurality of magnetic heads is replaced with the magnetic head in which the write error has occurred. Data is written twice using another magnetic head, and information indicating that the magnetic head has been changed is written in the non-contact type memory.
When reading data from the magnetic tape cartridge, the sensor unit reads out the management information of the non-contact type memory to determine whether the data written on the magnetic tape is double-written, and is double-written. If the data is double, the data written in duplicate by the two magnetic heads is read out. If only one of the data written in the double can be read out, one of the data is read out.
If both of the double-written data cannot be read, a read retry process is executed.

  According to the present invention, by writing data on a magnetic tape in duplicate, even if the magnetic head is temporarily contaminated, writing and reading can be performed if either head is satisfactory. Even if the magnetic tape is scratched, data can be reproduced if either data can be read. Furthermore, since the number of read retries can be reduced, a decrease in processing speed can be suppressed.

  FIG. 2 is a block diagram of a server system using a magnetic tape device (magnetic tape drive) according to an embodiment of the present invention as a backup device. A magnetic tape cartridge 1 loaded as a recording medium in the magnetic tape drive 4 includes a magnetic tape 2 and a non-contact type memory 3. The magnetic tape drive 4 includes a magnetic head 5 that can write / read magnetically with respect to the magnetic tape 2 of the magnetic tape cartridge 1 and a sensor unit 7 that can write / read wirelessly with respect to the non-contact type memory 3. And a drive control unit (control unit) 8 for controlling them. A system device 9 such as a server has a CPU 10, a memory 11, and a hard disk device 12.

  FIG. 3 is an external view showing the inside of the magnetic tape cartridge 1 in a transparent manner. A magnetic tape 2 is accommodated in the magnetic tape cartridge 1 and a non-contact type memory 3 for recording management information of the magnetic tape 1 is incorporated. The non-contact type memory 3 is, for example, a non-contact type IC card or the like, and can be read / written in a non-contact manner by an RF interface having a wireless communication function.

  In the system shown in FIG. 2, an instruction to write or read data is issued from the system device 9 to the magnetic tape drive 4, and data recording or reproduction is performed on the magnetic tape 2. When the system device 9 instructs the magnetic tape drive 4 to write data, the data is transferred from the system device 9 to the magnetic tape drive 4, and the magnetic head 5 applies the magnetic tape 2 to the magnetic tape 2 according to an instruction from the drive control unit 8. Writing begins. At that time, data is duplicated by writing the same data in two places. When the data is written in duplicate, information indicating that the data is duplicated is written in the non-contact type memory 3 by the sensor unit 7 provided in the RF interface 6. Specifically, a flag indicating that data has been double-written in the non-contact type memory 3 is set.

  When the system device 9 instructs the magnetic tape drive 4 to read data, the recorded content of the non-contact type memory 3 is read by the sensor unit 7 of the RF interface 6 and the data duplication writing flag is set. The data is read from the magnetic tape 2 by the magnetic head 5. At this time, if only one of the duplicated data can be read, the data is continuously read and the data is transferred to the system device 9.

  FIG. 1 is a diagram showing the relationship between the data format of the magnetic tape 2 and the magnetic head 5. The magnetic head 5 includes a write head and a read head b, and a plurality of magnetic heads 5 are arranged in the width direction of the magnetic tape 2. In FIG. 1, two magnetic heads 5 are shown, the write heads are indicated by 13a and 14a, and the read heads are indicated by 13b and 14b. Of course, two or more magnetic heads 5 can be arranged. By the write heads 13a and 14a, the same data is written in two places on the magnetic tape 2 in units of data blocks A, B, C, and D. In FIG. 1, data is written in parallel to the traveling direction of the magnetic tape 2, thereby duplicating data. Further, it is possible to check whether or not a write error has occurred by reading the data written by the write heads 13a and 14a with the read heads 13b and 14b.

  FIG. 4 is a flowchart showing processing when data is written from the system apparatus 9 to the magnetic tape 2 in the system shown in FIG. With reference to FIG. 4, the processing when a write instruction to the magnetic tape cartridge 1 is issued from the system apparatus 9 to the magnetic tape drive 4 will be specifically described. First, data to be written is transferred from the system device 9 to the magnetic tape drive 4 (step 401). Next, under the control of the drive controller 8, the same data is written to the magnetic tape 2 by the magnetic head 5 in two places (step 402). After data is written in duplicate on the magnetic tape 2, a flag indicating duplex writing is written in the non-contact memory 3 by the sensor unit 7 of the RF interface 6 (step 403). Here, the written data is read by the read heads 13b and 14b, and it is confirmed whether or not a write error has occurred (step 404). If no write error has occurred, the process ends normally.

  If a write error has occurred, it is checked whether or not there are two or more magnetic heads 5 in which no error has occurred, including previous writing (step 405). When there are two or more magnetic heads 5 in which no write error has occurred, the magnetic head 5 in which the write error has occurred is not used, and data is written in a duplex manner using the magnetic head 5 in which no write error has occurred. Then, the data indicating the dual writing and the flag indicating the changed magnetic head 5 are written in the non-contact type memory (step 406). If a write error has occurred in all the magnetic heads 5 that have been written in duplicate, write error processing is performed (407). For write error processing, if the magnetic head has an automatic cleaning function, the magnetic head is automatically cleaned. If there is no automatic cleaning function, the operator is warned that the magnetic head needs to be cleaned. There is.

  FIG. 5 is a flowchart showing processing when the system device 9 reads data from the magnetic tape 2. When an instruction to read data is issued from the system unit 9 to the magnetic tape drive 4 (step 501), the recorded content of the non-contact type memory 3 is read by the sensor unit 7 of the RF interface 6 and there is a flag indicating duplex writing. Is confirmed (step 502). If there is a flag, it is determined whether data can be read from the magnetic tape 2 by the magnetic head 5 (step 503). This determination can be made based on whether or not the reproduction output of the magnetic head 5 has reached a predetermined level. If the data can be read, the duplicated data is read from the magnetic tape 2 (step 504), and the data is transferred to the system unit 9.

  In step 503, if there is a magnetic head that cannot be read, it is determined whether only one of the duplicated data can be read (step 505). If there is a magnetic head that can be read, the magnetic head 5 can read the magnetic tape. The data is read from 2 (step 506), and the data is transferred to the system device 9. In step 505, if reading from any of the magnetic heads is not complete, read error processing is performed (step 507). The read error process in this case is a read retry process, for example. In step 506, if an error has occurred in the read data and reproduction cannot be performed correctly, error correction processing is performed in step 507. In step 502, if there is no flag indicating duplex writing, it is recognized as normal writing processing, and normal reading processing is executed (step 508).

  According to the above embodiment, data is written in duplicate, so that even if the magnetic head is temporarily contaminated, writing and reading can be performed if either head has no problem. Even if the magnetic tape is scratched, data can be reproduced if either data can be read. Furthermore, since the number of read retries can be reduced, a decrease in processing speed can be suppressed.

It is a figure which shows the relationship between the write data format and magnetic head in the magnetic tape apparatus by the Example of this invention. 1 is a block diagram of a system in which a magnetic tape device according to an embodiment is used as a backup device. It is a general-view figure of the magnetic tape cartridge which incorporates a magnetic tape and non-contact-type memory. It is a flowchart which shows a process when a system apparatus writes data on a magnetic tape. It is a flowchart which shows a process when a system apparatus reads data from a magnetic tape.

Explanation of symbols

1 ... Magnetic tape cartridge,
2 ... Magnetic tape,
3 ... Non-contact memory,
4 ... Magnetic tape drive,
5 ... Magnetic head,
6… RF interface,
7 ... sensor part,
8 ... Drive controller,
9 ... System device,
10 ... CPU,
11 ... Memory,
12. Hard disk device,
13a, 14a ... write head,
13b, 14b... Read head.

Claims (5)

In a magnetic tape device for writing and reading data to and from a magnetic tape cartridge containing a magnetic tape and a non-contact type memory,
A plurality of magnetic heads comprising a write head and a read head;
A sensor unit for writing management information of the magnetic tape to the non-contact type memory;
A control unit for controlling the plurality of magnetic heads and the sensor unit,
Under the control of the control unit, information indicating that the same data is written twice on the magnetic tape using two of the plurality of magnetic heads, and information is written on the magnetic tape. A magnetic tape device for writing into the non-contact type memory.   2. The magnetic tape device according to claim 1, wherein the double writing is performed in parallel with the traveling direction of the magnetic tape.   When the double-written data is read using the magnetic head and it is detected that a write error has occurred from the read data, the magnetic head of the plurality of magnetic heads is replaced with the magnetic head in which the write error has occurred. 2. The magnetic tape device according to claim 1, wherein data is written twice using another magnetic head, and information indicating that the magnetic head is changed is written in the non-contact type memory.   When reading data from the magnetic tape cartridge, the sensor unit reads out the management information of the non-contact type memory to determine whether the data written on the magnetic tape is double-written, and is double-written. If the data is a double-written data, the two magnetic heads read out the double-written data. If only one of the double-written data can be read out, the other data is read out. The magnetic tape device according to claim 1.   5. The magnetic tape device according to claim 4, wherein a read retry process is executed when both of the double-written data cannot be read.

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