JP2001014604A - Data writing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make rewritable in a short time by a simple process when a writing error occurs in a magnetic tape concerning the data writing system of a magnetic tape device in which an internal block gap is arranged between data blocks for writing and a read after write check function is provided. SOLUTION: The system is provided with a means 11, which determines the data block length of a data buffer that stores the data blocks to be written into a magnetic tape, a padding data adding means 13 and a writing control section 12. The section 12 discriminates whether the recording length, which includes the data block length discriminated by the means 11 and an IBG, exceeds the distance between the writing head of the magnetic tape and the reading head or not. When the recording length does not exceed the distance, the means 13 is driven to add padding data to the data blocks so that the recording length exceeds the distance between the heads.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a data writing system for a magnetic tape device.

When writing data to a magnetic tape device, the size of a physical block is variable, and an internal block gap (IBG) is written between each physical block. Also, in the magnetic tape device, when data is written by the write head, immediately after that, the data is read by the read head, the data is compared with the written data, and it is checked whether the data is written correctly. In order to perform rewriting upon detection, the magnetic tape is rewound so that the portion in front of the block where the error has been detected is located at the position of the write head.

It is desired to simplify the control of rewriting when such a writing error of the magnetic tape is detected.

[0004]

2. Description of the Related Art FIG. Is the configuration of data recorded on the magnetic tape; Indicates the configuration of a physical block. A. In the figure, 80 is a magnetic tape, 81 is a data block for management, 82 is an internal block gap (IBG), 83 is a TM (tape mark), and 84 is user data.

In the magnetic tape device technology, physical blocks (data 81 for management, IBG 82, TM83, user data 8) when writing data to the magnetic tape 80 are used.
4) is from 1 byte (Byte) to 451 kilobytes (KByte). This size is usually related to the maximum number of transfer bytes of the interface of the host device. The host device manages the data on the medium by setting the data to be written to a certain size and writing the data.

In general, in the standard label format (hereinafter referred to as SL), data for management (the length of the user data,
Name etc.) 81 is written, the length is 80 bytes, and two or three pieces of data for this management are written, and the physical size when written to the medium is 0.3 m
m (when the tape speed is 2 m / sec). When writing data on the magnetic tape 80, an IBG 82, which is data of a specific pattern, is written to indicate between physical blocks including various types of data. This size is defined in the range of 1.6 mm (minimum) to 3.0 mm (maximum) (the tape speed is assumed to be 2 m / sec as described above), and 2.0 mm is used as a standard size. .

FIG. 1 shows a configuration of a conventional physical block. In this example, the width (the number of tracks) of the magnetic tape is 18
And 18-bit data can be written in parallel at the same time. At the beginning and end of the physical block, patterns for controlling the physical block (so-called,
A preamble 90 and a postamble 92 (which are different from the data of “0” and “1”) are arranged, and a data portion 91 of “1” and “0” is written between them. The data portion 91 includes a user data portion 91a in which 14-bit data is written in parallel, a padding portion 91b for writing a fractional part (bits not divisible by 14 bits) of the data of the user data portion 91a, and a user data portion 91b. Error checking and correction for 4 bits in parallel with each 14 bits of the padding portion 91a and the padding portion 91b (EC
C) An area for storing bits such as bits is provided. Note that the padding portion 91b is a pattern composed of "1" and "0" indicating that the padding is a predetermined padding, and differs from the preamble 90 and the postamble 92 in the nature and configuration of the signal.

FIG. 7 is an explanatory view of the positions of the write head and the read head and the retry when a write error occurs. FIG. , 80 is a magnetic tape, 85 is a write head,
86 represents a read head.

At the time of writing, after writing the N-th data on the magnetic tape 80 by the write head 85, the IBG
Then, the (N + 1) th data is written. At this time, the N-th data passes through the read head 86, and it is checked whether or not there is a write error due to the read-after-write of the N-th data. If no error is detected in this check, it is determined that the Nth data has been written normally. However, when there is a data error due to medium loss, etc., N
A retry process for writing the second data block again is required.

In this case, FIG. N + 2 like
Even during the writing of the Nth data, the writing is interrupted, and the Nth data is rewritten. In the case of (1), the magnetic tape is returned by one data block (in the figure, the state where each magnetic head is moved and the magnetic tape is relatively returned). In this state, the magnetic tape does not return to the position of the data block N. Then, as shown in the figure, when the data block is returned by two data blocks, the write head can rewrite the data block N, and the rewriting of the data block N is completed in the state described above, and then the data block N + 1 is rewritten. Write. Thereafter, the rewritten data block N is read in the state described above, and inspection is performed, and the same inspection is performed on the data block N + 1.

[0011]

According to the prior art,
If an error is detected by the read-after-write inspection of the magnetic tape, it is necessary to go back by a plurality of data blocks and perform rewriting. The control operation of returning the magnetic tape to the position of the IBG immediately before the data block) is complicated and time-consuming, and there is a problem that a slight displacement occurs at this time.

When the number of bytes of the write information is equal to or less than the set value, writing the data block after increasing the IBG length is disclosed in Japanese Patent Application Laid-Open Nos. 56-34120 and 56-8.
No. 0810. Further, Japanese Patent Application Laid-Open
According to Japanese Patent Application Laid-Open No. 60418, when recording a data block having a number of devices less than the number of bytes on a magnetic tape corresponding to the interval between a write head and a read head, a preamble or a postamble is added to the data block, and A method is disclosed in which the number of bytes on the magnetic tape corresponding to the interval is equal to or greater than the number of bytes.

[0013] However, even if the technique disclosed above is used, there is a provision that the IBG length is 3.0 mm at the maximum, so that it is not possible to cope with the case where the length needs to be longer than that. there were. In the above technique, the length of the preamble or postamble is also
There was a problem that it was restricted by regulations.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a data writing method for a magnetic tape device which enables simple rewriting in a short time when a writing error occurs on a magnetic tape.

[0015]

A first principle of the present invention is to limit a minimum block size for writing on a magnetic tape,
Before the read inspection of the Nth block is completed, the (N + 1) th
The padding is added to the data so that the size of the block does not end.

The second principle of the present invention is that the IBG part is 7.8 m in standard depending on the block size to be written on the magnetic tape.
The IBG length is changed by writing an erase pattern having a size of m so that the writing of the (N + 1) th block does not end before the inspection of the Nth block is completed.

FIG. 1 is a diagram illustrating a first principle of the present invention.
A. Is the first principle configuration; FIG. 4 is a diagram showing a state where the data block length on the magnetic tape is increased. A. In the figure, 1 is a writing unit, 10 is a data buffer, 11 is a data block length determining unit, 12 is a writing control unit, 13 is padding data adding unit for adding padding data, 14
Is a write circuit. B. 2 is magnetic tape, 20 is IB
G and 21 are data blocks (N and N + 1 represent block numbers), 22 is padding data, 3 is a write head,
4 is a read head, X (mm) is the distance between the write head and the read head (more precisely, the distance between the magnetic gaps of each head), Lib (mm) is the IBG length, and Lblk (mm) is the physical block of data. Indicates length.

According to the first principle of the present invention, the IBG length (Li
b) Assuming that the minimum value is 1.6 mm, the standard value is 2.0 mm, and the maximum value is 3.0 mm, the writing of N + 1 blocks is not completed before the completion of the read-after-write inspection of N blocks. , The required physical block length (Lblk) for the minimum IBG length is X-1.6 (mm)
The required physical block length (Lblk) is X-2.0 (mm) or more for the standard IBG length, and X-3.0 (mm) or more for the maximum IBG length. is there. Therefore, when a data block is stored in the data buffer 10 of the writing unit 1 from a host (not shown), the data block length determining unit 11 determines the stored data block length, and the write control unit 12 The above conditions (N before the completion of the read-after-write inspection of N blocks)
(Writing of +1 block is not completed) is determined.

That is, even when the IBG length is set to the minimum value, the physical block length (Lblk) of the data is equal to the X-length.
It is determined whether it is 1.6 (mm) or more. At this time, the length in the case where the data length is converted into the recording density of the magnetic tape is determined.
Only the data of 0 is output to the write circuit 14 and written as a data block. If the data is not satisfied (X-1.6 is not reached), the padding data adding means 13 is driven to In a format added to the data block 21, padding data 22 of an amount corresponding to the length satisfying the above condition (insufficient length) is generated and supplied to the writing circuit 14; The data block is written in a format in which padding data 22 is added to the data block 21 as shown in FIG. As a result, the data block length is increased, and the writing of the (N + 1) -th data block does not end before the inspection of the N-data block ends.

FIG. 2 is a block diagram showing the second principle of the present invention.
A. Is the second principle configuration. FIG. 4 is a diagram showing a state where the IBG length on the magnetic tape is increased. A. of FIG. At
1 are denoted by the same reference numerals, 1 is a writing unit,
10 is a data buffer, 11 is a data block length determining means, 12 is a writing control unit, 14 is a writing circuit, 15 is a normal IBG generating means, and 16 is an erase (ERASE) pattern generating means added to the IBG. . B. of FIG. 2 is a magnetic tape, 20 is an IBG, 21 is a data block (N,
N + 1 represents a block number), 23 represents an erase pattern (denoted by ERASE), 3 represents a write head, 4 represents a read head, and X (mm), Lib (mm), and Lblk (mm) are the same as those in FIG. Therefore, the description is omitted.

According to the second principle of the present invention, in order to maintain a positional relationship in which writing of the (N + 1) -th block is not completed before the inspection of the N-block is completed, the distance (X) between the write head and the read head is set. When the block length (Lblk) is minimum (1 byte), control is performed to change the IBG length without changing the block length. In this case, the required IBG length is (X
-Minimum Lblk). However, the maximum length of the IBG length is specified in advance, and may exceed the specified length. Specifically, when the maximum length of the IBG length is defined as 3.00 mm, the block length is 1 byte and the recording length is 0.
When the distance between the write head and the read head is 3.81 mm at 26 mm, the required IBG length is 3.81.
-0.26 = 3.55 mm, exceeding the specified value.

In order to cope with this, in the second principle configuration, the data block length written in the data buffer 10 is determined by the data block length determining means 11, and the write control unit 12 uses the normal IBG length. It is determined whether the above condition (the writing of the (N + 1) block is completed before the reading check of the N block is completed) is satisfied.
The BG generating means 15 is driven to generate an IBG having a standard length, and the erase pattern generating means 16 is also driven.
An erase pattern is generated in addition to the standard IBG.
B. As shown in IBG20 and erase pattern 23
And IBG 20 are written by the writing circuit 14 in order. The erase pattern has a standard length of 7.8 mm, and a large number of erase patterns can be written continuously. The erase pattern is usually a signal pattern to be written in order to skip a defective medium portion. Therefore, it is usually skipped at the time of reading, and does not affect the reading operation.

As described above, by writing an erase pattern, it is possible to secure a predetermined distance or more between adjacent data blocks.

[0024]

FIG. 3 shows a hardware configuration of an embodiment of the present invention. This embodiment can implement the first principle configuration of the present invention shown in FIG. 1 and the second principle configuration of the present invention shown in FIG. In the figure, 3 is a write head (W
T HEAD), 4 is a read head (RD HEAD),
Reference numeral 30 denotes an MPU (microprocessor unit) for controlling the magnetic tape device, which corresponds to the write control unit 12 in FIGS. 1 and 2, 31 is a memory storing programs and data, and 32 is an interface with a host. S to control
CSI (Small Computer System Interface) control circuit,
33 is a data buffer for temporarily storing write data and read data, 34 is a pattern creation circuit for creating an IBG or an erase pattern (ERASE) for substantially expanding the IBG according to the present invention, and 35 is a 9-bit to 8-bit data. A data conversion circuit for conversion, 36 is an ECC (error detection and correction) code generation and an ECC generation padding generation circuit for generating padding data, and 37 is a multiplex for sequentially selecting data or a pattern from each circuit represented by reference numerals 34 to 36. The circuits (MPX) and 38 are write circuits.

Reference numeral 40 denotes a read circuit for detecting data from an analog signal read from the read head 4, reference numeral 41 denotes a pattern detection circuit for detecting each pattern (IBG, erase pattern, etc.), and reference numeral 42 denotes a pattern for a signal from the read circuit 40. An ECC circuit 43 for performing error detection and correction by performing processing including the detection signal of the detection circuit 41, and a circuit 43 for performing data conversion (9-bit to 8-bit conversion) on the output from the ECC circuit 42.

FIG. 4 is a processing flow for expanding a data block according to the embodiment, which is executed in the hardware configuration shown in FIG. The processing flow of this embodiment corresponds to the first principle of FIG.

Host to SCSI controller (32 in FIG. 3)
The data is transferred to the data buffer (33 in FIG. 3) via the interface (S1 in FIG. 4), and the completion of the transfer is confirmed (S1 in FIG. 4).
2). When the transfer is completed, it is determined whether or not the data byte is equal to or larger than a specified value (S3). Whether the data byte is equal to or larger than the specified value is determined by determining that the physical block length (Lblk) of the data when the IBG length described with reference to FIG. 1 is set to the minimum value (1.6 mm) is X-1.6. (Mm) is determined. If it is equal to or more than the specified byte, the data byte of the data buffer is written with the same size (S5 in FIG. 4). If the data byte does not reach the specified byte, padding is added so as to be equal to or more than the specified byte (S4).

To explain this data block enlargement in a concrete example, if the distance between the head gap between the write head and the read head is 3.81 mm and the IBG length (Libg) is 1.6 mm, which is the minimum, N blocks N before inspection is completed
The physical block length (Lblk) at which the writing of the +1 block is not completed is 3.81 mm-1.6 mm = 2.21.
mm.

The data amount of the physical block for setting the physical block size to 2.21 mm or more can be obtained by the following calculation.

Physical block size (Lblk) = [(NByte / 14)
+28] × (9 × 1.028 × 0.001) where “N” is the byte length of the desired block size,
"14" indicates that the number of bits recorded in parallel with the tape width is 18 bits, the number of data bits is 14, and the remaining 4 bits are ECC (error check and correction) bits.
“28” is the number of preamble and postamble bits,
"9" indicates that the original 8 bits (1 byte) are converted to 9 bits and recorded, and "1.028" is the length when 1 bit is recorded in this embodiment (the unit is micrometer μm). ), And “0.001” is a numerical value for changing μm to mm.

Therefore, the number of bytes N to be obtained is represented by the following equation: NByte = [{Lblk / (9 × 1.028 × 0.001)｝ − 28] × 14 Even if the IBG length is in the minimum state, this relationship is guaranteed. Is N = [｛2.21 / (9 × 1.028 × 0.001)｝ − 28] × 14 = [(2.21 / 0.009252) -28] × 14 = 2952.14 Bytes, and it is necessary that N = 2953 bytes or more.

In order to set the minimum value of the physical block size to be written on the medium to 2953 bytes or more on the magnetic tape device side,
In the processing flow of FIG. 4 described above, even if the minimum block size is less than 2953 bytes in the format for writing data to the medium inside the magnetic tape device without changing the specification on the interface with the host, the 2953 bytes can be used.
The padding data is added and the size is changed so that the size becomes more than bytes, and the data is written. At the time of reading, only data of the original size is sent to the host.

FIG. 5 is a flowchart of an IBG enlargement process of the embodiment, which is executed in the hardware configuration shown in FIG. The processing flow of this embodiment corresponds to the second principle of FIG.

From host to SCSI controller (32 in FIG. 3)
The data is transferred to the data buffer (33 in FIG. 3) via the interface (S1 in FIG. 5), and the completion of the transfer is confirmed (S1 in FIG. 5).
2). When the transfer is completed, the data byte is written (S3), and it is determined whether the data byte is equal to or larger than a specified value (S4). The determination as to whether or not the data byte is equal to or greater than the specified value is to determine whether or not the data block length described with reference to FIG. 2 is equal to or greater than a predetermined byte. If the length is equal to or more than a predetermined byte, a standard IBG length is written (S in FIG. 5).
6) If the number does not reach the predetermined byte, an erase pattern is written (S5), and then a standard IBG length is written.

The expansion of the IBG will be described with a specific example.
If the distance between the head gap between the write head and the read head is 3.81 mm and the IBG length (Libg) is standard (2.0 mm), 3.81 mm−2.0 mm =
1.81 mm, and the block length does not reach 1.81 mm (data amount is 1 byte / 0.26 mm to 2346
In the case of (byte / 1.81 mm), an erase pattern is written in addition to IBG writing. Since the erase pattern is 7.8 mm in this embodiment, the data amount obtained by adding the erase pattern to the IBG length can prevent the N + 1 block from being completely written before the N block check is completed.

[0036]

According to the present invention, when a write error is detected in recording on a magnetic tape, unnecessary position control is not required, and the overall processing time can be shortened.
Further, by performing complicated position control, it is possible to suppress the occurrence of a position shift.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first principle configuration of the present invention.

FIG. 2 is a diagram showing a second principle configuration of the present invention.

FIG. 3 is a diagram illustrating a hardware configuration of an embodiment of the present invention.

FIG. 4 is a diagram illustrating a processing flow for expanding a data block according to the embodiment;

FIG. 5 is a diagram showing a processing flow of IBG enlargement of the embodiment.

FIG. 6 is an explanatory diagram of a conventional technique.

FIG. 7 is an explanatory diagram of positions of a write head and a read head and a retry when a write error occurs.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Writing part 10 Data buffer 11 Data block length discriminating means 12 Writing control part 13 Padding data adding means 2 Magnetic tape 20 IBG 21 Data block 22 Padding data 3 Write head 4 Read head X Read head X Interval between write head and read head Lib IBG length Lblk Data block length

Claims (2)

[Claims] In a data writing method of a magnetic tape device having a function of reading and writing after arranging internal block gaps between data blocks and storing data blocks to be written to a magnetic tape, Means for determining the data block length of the buffer, padding data adding means, and a write control unit, wherein the write control unit determines the data block length determined by the data block length determination means and the recording length including IBG Discriminates whether the distance between the write head and the read head of the magnetic tape does not exceed, and if not, drives the padding data adding means to add padding data to the data block so as to exceed the distance between the heads. A data writing method. 2. A method for determining a data block length of a data buffer for storing a data block to be written on a magnetic tape in a data writing method on a magnetic tape in which an internal block gap is arranged between data blocks and writing is performed. And an erase pattern generating means, and a write control section, wherein the write control section has a data block length determined by the data block length determining means and a recording length including IBG read from the write head of the magnetic tape. A data writing method for writing an erase pattern from the erase pattern generating means together with a standard-length internal block gap to the data block if it is determined whether the distance from the head is not exceeded;