JPH0373401A - Magnetic tape device - Google Patents

Abstract

PURPOSE:To enforce the efficiency of using a magnetic tape by erasing the data on a recording position by an erasing circuit in the case that the data is recorded on the recording position to be accessed by the different type of devices and writing the data on that position based on information in a system area at the time of writing the data. CONSTITUTION:In the case that writing command is given by a host device, whether preceding data to be recorded on a specified stripe on which the data is written by the other type of the devices or not is checked by volume control information stored in a memory 2. In the case that the data is written by the other type of the devices, the erasing circuit 7 is driven so as to output a high AC to a writing heat 10 and to move the magnetic tape 22, therefore, a high AC magnetic field is received at the time of passing through the gap part of the writing head 10, and a data signal which is recorded after being once magnetized to be in a saturated state is completely erased. After erasing, the data is written. Thus, a cartridge tape on which the data is written by the lower rank type of the devices having a low recording frequency can be used as it is, and the efficiency of using the magnetic tape 22 can be enforced.

Description

[Detailed Description of the Invention] E-Summary] Regarding magnetic tape devices used as external storage devices for computer systems, we have developed a magnetic tape device that facilitates the use of magnetic tapes used in conventional devices with low recording frequencies, which are lower models. With the aim of streamlining the operation of the system, the system area at the beginning of the magnetic tape, where record management information including information on the model that wrote the data is stored, is read at startup, and the read record management information is transferred to the host device. In a magnetic tape device that reads/writes data by referring to the record management information and accessing the specified recording position in response to a command from a host device, An erase circuit is provided that generates an AC 141 field that erases the magnetism of the magnetic field, and when data is written in response to a command from a host device, it is possible to check whether data is being written to a specified recording position by a device of a different type. If it is checked based on the recording management information and data is being written by a different type of device, the erase circuit is driven to magnetically erase the designated recording position, and then the data is written. Configure it to do so.

[Industrial Field of Application] The present invention relates to a magnetic tape device used as an external storage device for a computer system, and in particular, the present invention relates to a magnetic tape device used as an external storage device of a computer system, and in particular, it is possible to use a magnetic tape written on by another model, such as a lower model with a significantly different recording frequency, without any problem. The present invention relates to a magnetic tape device that can perform

In recent years, with the improvement of processing power and increased use of computers such as faster speeds and larger capacities, there has been a demand for larger capacities and smaller sizes of external storage devices such as magnetic Y disk devices and magnetic tape devices. New G9 types and systems are being offered one after another. Among these, magnetic tape devices are required to reduce the storage space and increase the capacity of magnetic tape media from the viewpoint of backup or data storage of magnetic disk devices. A cartridge library system using a type of cartridge tape device is provided. Furthermore, in that cartridge tape device,
So-called enhanced machines have been provided which can increase the recording density and storage capacity compared to conventional models by increasing the recording frequency. The cartridge tape, which is the storage medium, is a wide magnetic tape that has been formatted in advance, and the recording data is placed in a cartridge case, with the system GL area for recording information etc. assigned to the beginning of the tape. The same cartridge tape is used for both conventional and enhanced models.

[Prior art] In a magnetic tape device, if the data recording frequency is the same, when the recorded magnetic tape is rewritten (override), the previous data is erased and new data remains because the recording is saturated. Become. However, if the recording frequencies are different, the previous data may not be completely erased.

FIG. 5 is an explanatory diagram showing the magnetic field produced by the ring-shaped hend, in which (a) shows writing at a low frequency and (b) shows writing at a high frequency. The head generates a semicircular magnetic field as a whole by the N and S poles on both sides of the gap, and as shown in the figure, as the frequency increases, the magnetic field does not reach the deeper layers of the magnetic layer.9 Therefore, writing at low frequencies is impossible. The residual magnetization of the magnetic layer generated in the magnetic layer cannot be erased by a magnetic field at a high frequency.

Normally, magnetic tape devices use a low frequency (1f) and its 2nd frequency.
With two types of recording frequencies, twice as high frequency (2f),
“0” and “l” are being recorded. In this case, if data is recorded at a low frequency (1f) and then recorded at a high frequency (2r), the previous data will not be completely erased because the saturation point of the tape differs depending on the frequency.

However, if the frequency difference is about twice as large, the output of the previous data is small, so it is not a practical problem.The extent to which the frequency difference does not become a problem can be determined by calculating the overwrite characteristic (T) formula shown below. It is determined by the value. If the value of this override characteristic (T) is below a certain level, override is possible.

However, if the frequencies are extremely far apart, if the previous data written at a lower frequency is overwritten with a higher frequency, the residual magnetization is large and noise is generated, worsening the S/N ratio and causing read errors. Resulting in.

[Problems to be Solved by the Invention] However, as mentioned above, in the helical scan type cartridge tape device, the same cartridge tape as before is used, but the cartridge tape is improved by increasing the recording frequency and recording density. The following is an example of a comparison of recording frequencies.

In this example, the frequency difference between If of the conventional device, which is a lower model, and 2f of the enhance device is 3.25 times, and when an attempt is made to rewrite the recording on the cartridge tape used in the conventional device by overriding in the enhance device, Since the data recorded in the conventional device is not completely erased, a read error occurs due to noise. Therefore, the cartridge tape used in the conventional device cannot be used as is in the enhancement device, making the use of the cartridge tape inefficient.

The present invention was created in view of these problems, and
It is an object of the present invention to provide a magnetic tape device that can facilitate the use of magnetic tapes used in conventional devices with low recording frequencies, which are lower models, and can improve the efficiency of magnetic tape operation.

[Means for Solving the Problems] Means in the present invention for achieving the above object is to read the system area at the beginning of the magnetic tape, where record management information including model information that has written data, is stored at startup. , transfers the read record management information to the host device and holds it within itself, and in response to a command from the host device, accesses the specified recording position by referring to the record management information and reads the data. /A magnetic tape device that performs writing is provided with an erase circuit that generates an alternating magnetic field in the write head to erase the magnetism on the magnetic tape.
When data is written by a command from a host device, the record management information is used to check whether data is being written to the specified recording position by a device of a different model, and the data is written by a device of 4 models. The magnetic tape device is characterized in that, when a recording is being performed, the erase circuit is driven to magnetically erase the designated recording position, and then data is written.

[Operation] For example, in a cartridge tape used in a helical scan type magnetic tape device, the format on the tape is determined in advance, and a system area is arranged at the beginning of the tape. In the system area, the positioning of data records is information.

Recording management information such as information for identifying different models such as recording methods and recording frequencies is stored.

In the magnetic tape device of the present invention, when data is written, it is determined based on the information in the system area whether the recording position to be accessed is recorded by a device of a different model, and the recording is performed by a device of a different model. If so, the data at that recording position is erased by the erase circuit, and data is then written. As a result, even if the magnetic tape has been written to, for example by another model with a low recording frequency, the data will be automatically selected and the magnetic data written by the low frequency will be completely erased. You can use magnetic tape freely without having to worry about whether it has been written by another model, making the use of magnetic tape more efficient. Furthermore, noise due to residual magnetism is eliminated, the S/N ratio is increased, and data resolution can also be improved.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram of a cartridge tape device which is a helical scan type magnetic tape device according to an embodiment of the present invention. In the figure, I is configured with a ROM (read-only memory) that stores firmware, and the firmware controls the exchange of commands and data with the host device, as well as controlling the entire internal structure of the device. 2 is a read/write memory that is used as a buffer for transfer data, 3 is a mechanical M control circuit that controls a mechanical section consisting of a head drive section, a magnetic tape drive section, etc. (not shown), and 4 is a main control circuit. A read/write circuit converts the write data sent from the circuit 1 into a write signal to the write head 10, and also reproduces the signal read from the read head ti into read data and sends it to the main control circuit l.
This is a write (R/W) circuit, and the main control circuit 1 controls the mechanical control circuit 3 and the R/W circuit 4 to access a desired recording position W on the magnetic tape and read/write data. Control the lights. 5 is a write amplifier that amplifies the write signal from the R/W circuit 4, 6 is a read amplifier that amplifies the read signal from the read head 11, and 7 is an alternating current for magnetic erasing that is supplied to the write head 10 via the write amplifier 5. This is an erase circuit that gives By driving the erase circuit 7 and outputting a large alternating current to the write head 10 and moving the magnetic chip, the magnetic tape is erased from the write head 10 as shown in FIG. 4(a).
When passing through the gap of 0, it receives a strong alternating magnetic field,
- Data signals that have been magnetized and recorded to a saturation state are completely erased. As the distance from the gap increases, the alternating current magnetic field applied to the tape decreases while reversing its polarity many times in the positive and negative directions.
), drawing a loop like the magnetization curve shown in (
When the magnetic field reaches a neutralization point, the residual magnetism becomes zero and magnetic erasing is performed.

FIG. 2 is an explanatory diagram of the recording format of the cartridge tape device. As shown in the figure, the cartridge tape device uses a wide magnetic tape 22 housed in a cartridge 21. This magnetic tape 2
2, a system area 23 is allocated to the starting end, and a data area 24 is allocated after that. Each area consists of a plurality of processors, and each block contains a read/write processing unit, which is a head storage area. A plurality of stripes are formatted in which data is read or written in one revolution. Data access is performed by direct block-by-block access, and striping within a block is performed by sequential access. System area 23
Stored therein are the serial number of the cartridge, information on the position of the file which is the management unit of the host device, and volume management information (recording management information) such as information on the model of the machine that has written for each file.

FIG. 3 is a control flowchart of the main control circuit 1 in the above txt2. The control will be explained according to the numbers shown in the figure: (1) When the apparatus is started, it is first checked via the mechanical control unit 14 whether or not a cartridge tape has been set.

(2) When the cartridge tape is set, the system area is read.

(3) Transfer the read volume management information to the host device and store it in the memory 2.

(4) Next, wait for a command from the host device, and (5) If the command from the host device is a write command, the previous data recorded in the specified stripe to be written is written by another model. It is checked based on the volume management information stored in the memory 2 whether or not this is the case. If it is based on the model, go to step (7).

(6) If it is of another model, drive the erase circuit 7 to erase the designated stripe.

(7) Write the data sent from the host device to the specified stripe.

(8) Record in the volume management information stored in the memory 2 that the written stripe data is new data including that it is based on the model.

(9) If the write process is not completed, return to (5) and repeat the process for the next specified stripe.

If the write process is completed, the process returns to (4) and waits for the next command.

(10) If the command from the host device is a read command, read the data of the specified stripe and transfer it to the host device.

(11) If the read is not completed, return to (10) and repeat the same process for the next designated stripe; if the read is completed, return to (4) and wait for the next command.

(12) If the command from the host device is an ejection command, the updated volume management information stored in memory 2 is written to the system area, the tape is rewound, and the cartridge is ejected. Then, the process returns to (1) and waits for the next cartridge to be set.

In this way, in the cartridge tape device of this embodiment, when writing data, it is checked whether the stripe at the recording position has been written by another model, and if it has been written by another model, it is automatically erased. Lights were added later. This makes it possible to use cartridge tapes written with conventional models, which are lower-end models with lower recording frequencies, as is, and to record a mixture of data written with conventional models on a single cartridge tape. It is now possible.

[Effects of the Invention] As explained above, according to the present invention, data is written after automatically degaussing a storage area written in another model such as a conventional device that is a lower model.
It is possible to use magnetic tapes that have been written on other models as is, and it is also possible to mix and record data written on other models on a single magnetic tape, which has the effect of making magnetic tape operations more efficient. Since the generation of noise is suppressed, the SN ratio is increased, and the data resolution can be improved, this greatly contributes to improving the performance of such magnetic tape devices.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a cartridge tape device according to an embodiment of the present invention. FIG. 2 is a magnetic tape recording format in the embodiment. FIG. 3 is a control flowchart of the main control circuit in the embodiment. FIG. 5 is an explanatory diagram of magnetic erasing of a tape. FIG. 5 is an explanatory diagram of a magnetic field caused by writing to a magnetic tape. 1... Main control circuit, 2... Memory, 3...
・Mechanical control circuit, 4... Read/Write circuit, 5... Write amplifier, 6... Read amplifier,
7...Erase circuit, 21...Cartridge, 22...Magnetic tape,
23...System area, 24...Data area.輛11i3 (a) Explanation of magnetic erasure Figure 4 Write at low frequency Write at high frequency (a) (b) #1v4a of magnetic field in write Figure 5

Claims (1)

[Claims] At startup, the system area (23) at the beginning of the magnetic tape where record management information including model information that has written data is stored is read, and the read record management information is transferred to the host device. In a magnetic tape device that is stored within its own device and reads/writes data by accessing a specified recording position by referring to the record management information in response to a command from a host device, the magnetic tape on the magnetic tape An erase circuit (7) is provided that generates an alternating magnetic field to the write head (10) to erase the data. If data is being written by a different type of device, the erase circuit (7) is driven to magnetically erase the specified recording position. A magnetic tape device characterized in that data is written after that.