JPS60672A - Magnetic tape device - Google Patents

Abstract

PURPOSE:To improve the error recovery efficiency by reading retrial by dividing a data block into segments, writing the data together with an error check code of each segment, and revising only a segment data in error among preceding read blocks at the retrial of reading. CONSTITUTION:A block data fed from a host 1 is supplied to a write head 4 added with an error check code at each segment at a write section 3 and written in block unit on a magnetic tape 5. A data read in block unit from a reading head 6 is detected for error at each segment data at a reading section 7, stored temporarily in block unit and when any error exists, the data is read again in block unit. Further, only the data of the segment having the said error is used for error recovery among the data read agin. The error in other segments is neglected. Thus, the error recovery rate is improved.

Description

[Detailed description of the invention] The present invention relates to a magnetic tape device.

In order to increase the reliability of data, conventional tape devices generate an error check code for each data block during writing, add the error check code to the data block, write it on the tape, and read it 11t. The read data block is checked for errors using the error check code 2, and if there is an error, it is reported to the host that a read error has occurred, and upon receiving a reread command from the host, it performs the same operation again. Reading data block. If the re-read data is incorrect somewhere in the block, it is necessary to read it again. In recent high-density magnetic tape devices, the quality of the media, dust, etc. have a large effect on the amplitude of the reproduced signal, making it more likely that an error will occur again near the location where an error occurred during the first reading. Very many. For this reason, the above-mentioned conventional apparatus has the disadvantage that the success rate of re-read attempts is low, it takes a long time to recover from an error, and a lot of time is wasted on the host due to read re-attempts.

It is an object of the present invention to solve the above-mentioned drawbacks of the prior art, to divide data blocks into segments and write them to tape with an error check mark for each segment, so that when retrying J÷, zZ of the previously read data blocks An object of the present invention is to provide a magnetic tape device that improves recovery efficiency by retrying reading by updating only the segment data that has been lost.

The magnetic tape device of the present invention includes a check mark '-'r optical generation IU circuit that inputs a series of block data and generates an error check code for each segment data consisting of a fixed number of data, and a a data number counting circuit that outputs a switching control signal for every certain number of data; and a switching circuit that inputs the input signal and the error check code and selects and outputs one of them according to the switching control signal. , a recording 1 (11 path) which converts the bottle input data outputted by the switching circuit and the error check code into a recording current and supplies it to the write head, and detects errors in each input block data and segment data of the data. 1- a reproducing circuit for reproducing and outputting the signal read by the reading head from the recording magnetic tape into a digital signal; a segment test circuit that tests the segment data for errors using data and an error check code related to the segment data; an error information holding circuit that holds the test results output from the segment test circuit; and a reproduction data output from the reproduction circuit. a switching circuit that selects and outputs output data of the temporary storage circuit described later; a switching control circuit that controls switching of the switching circuit depending on the output of the error information holding circuit; and an output of the switching circuit. and a temporary storage circuit for temporarily storing l blocks worth of data, and in a rereading attempt when the reproduced data is stored in the temporary storage circuit block by block and there is an error in the segment data in the block, It is characterized by comprising a reading unit that updates the segment data with an error by supplying only the segment data related to the segment with the error out of the newly read block data to the temporary storage circuit via the switching circuit. shall be.

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.

That is, the block data obtained by the host I is supplied to the write head 4 with a segment I, especially an error check code (I), written in the magnetic tape 5 at block C1 in the writing section 3. In reading lv, the data read out in block units from the reading unit 6 is detected as an error for each segment I data in the reading unit 7, and is stored in block units. is re-read in the middle of the block. Of the re-read data, only the data in the segment where the error occurred is used for error recovery. Errors in other segments are ignored. As a result, Error recovery rate can be increased.

FIG. 2 is a block diagram showing details of the writing section 3 of the second embodiment. That is, check code generation circuit 13. Data number counting circuit 16. Cutting circuit 8. It is composed of a recording circuit 11 and the like. The check mark F'f generation circuit E3 generates an error check code for each segment data of the block data inputted sequentially from the data signal line 9 and sends it to the switching circuit 8. The check code generation circuit 13 may be, for example, a well-known cyclic redundancy check (CRC) code generation circuit. The data number counting circuit 16 receives a nox signal that is sent from the host device through the control signal line 15 in synchronization with the transfer of the segment data components (for example, 1)<item data) to the data signal line 9. The pulse signals are counted manually, and a switching signal is output to the control signal line 17 when all data of one segment has been transferred. The switching circuit 8 receives the input data signal from the data signal line 9 and the data (R branch line 14) from the check code generation circuit 13.
The error check code input via the switching signal is selectively output. That is, each segment data of the input data block and the error check code related to the segment data are sequentially supplied to the recording path 11, and the recording circuit 11 converts the manual data into a recording current,
It is supplied to a write/rad (not shown) through the data signal line 12 to write on the magnetic tape. The recording circuit 11 is
It also includes functions such as error correction IF code generation, modulation, and formatting, but these are well-known techniques and are not directly related to the present invention, so their explanation will be omitted.

FIG. 3 is a diagram showing the structure of a data block written on a magnetic tape, in which a plurality of segments 19 are sequentially arranged from an arrow 18 indicating the tape starting end direction.

Each segment is composed of segment data 20 and error check code 21. This data block configuration is an example, and an error correction code and a synchronization code may be included in segment 1-19, and an error check code 2
1 may be written all at once in one predetermined segment without being included in the name segment 19.

FIG. 4 is a block diagram showing details of the reading section 7 of the second embodiment. That is, the reproducing circuit 27.degree. segment inspection circuit 28. Error information holding circuit 30° switching control circuit 32
．． Switching circuit 22. - Consists of time memory circuit 25 and the like. The regeneration circuit 27 amplifies, peak detects, and regenerates a clock using well-known techniques for one block of input signals inputted from a read head (not shown) via the data signal line 26.

The data is demodulated, error corrected, etc., restored to original data, and sent to the segment inspection circuit 28 and switching circuit 22 via the data signal line 23. The switching circuit 22 is set to an initial state prior to the first reading of block data, and selectively connects the data signal line 23 to the data signal line 24. Therefore, all data of the block is transferred to the temporary storage circuit 25 and once written t0.

In parallel with the above-described series of operations, the data on the data signal line 23'' is subjected to error detection for each segment by the segment inspection circuit 28. Error detection is possible using segment data and error check codes. The segment check circuit 28 supplies the check results to the error information holding circuit 30 via the control signal line 29, and the presence or absence of an error regarding each segment is determined by the error detection circuit 28. The data is held in the information holding circuit 30. If no error is detected in any of the segments, all the data of the block stored in the temporary storage circuit 25 is transferred to the 1-position device (not shown) through the data transmission line 31. be transferred. However, if an error is detected in at least one segment, then for that data block,
A read retry will be made.

In the case of an old reading attempt, first, the switching control circuit 32 issues a switching control signal (-) to the switching circuit 22 through the control signal line 33, and the switching circuit 22 connects the data signal line 23 to the switching circuit 22. i'J
# to connect the data signal line 34 to the data signal line 24. In parallel with the reread block data being sequentially output from the reproducing circuit 27, the first read data stored in the temporary storage circuit 25 is transferred to the data signal line 34. The signal 1f is stored in the temporary storage circuit 25 via the switching circuit 22 and the data signal line 24. On the other hand, the segment check circuit 28 detects an error in the re-read data on the data signal line 231-, but the error information holding circuit 30 ignores this,
When a segment in which an error is detected during reading of the first time l] is reached, this fact is transmitted from the error information holding circuit 30 to the switching control circuit 32 through the control signal line 35. By this, switching 11 no J 12 T) 1731 road 32
controls the 91-alternate 1-1 path 22 to connect the data signal line 23 to the data signal line 24.

Therefore, for segments in which an error was detected in the first read, the newly read segment data will be -
- It will be stored in the time memory circuit 25. When the reading of the segment is completed, this information is transmitted from the error information holding circuit 30 to the switching control circuit 32 through the control signal line 35, and the switching control circuit 32 controls the switching circuit 22 to disconnect the data signal line 23. The data signal line 34 is connected to the data signal line 24 again. By the above operation, when all the data of the block has been read, only the segment data in which an error was detected in the first read out of the first read data stored in the temporary storage circuit 25 is stored. is rewritten with the segment data read the second time. This one! ) The result of error detection during the second reading of the cleared segment data is of course held in the error information holding circuit 30. If there is no data error in these segment data, all data of the block is transferred from the temporary memory circuit J/S 25 to the host device through the data signal line 31. f
f At the time of the 12th reading, l+ in the same segment where an error was detected in the 1st reading
A reread attempt is made only if an error is detected. If the error in the segment is not recovered even after a predetermined number of reading retries, it is desirable to transmit this fact to the -1- device.

In this embodiment, when retrying reading, fiSi times]
Even if an error occurs in a segment other than the one in which the error was detected when reading ``, the retry is successful. Therefore, there is an effect that the success rate of retry is greatly improved compared to the conventional method. Further, since the read retry is performed by the present magnetic tape device alone, there is an advantage that no wasted time is caused to the host.

As described above, in the present invention, when writing block data, error detection codes are added to each segment of the block data and written to the magnetic tape, and when reading, the read block data is temporarily stored. At the same time, the read data is checked for errors segment by segment, and the segment with the error is memorized. When retrying reading, only the segment with the error is stored in the temporary memory using the re-read segment data. Since the segment data in the storage circuit is configured to be occupied, there is an effect that the success rate when retrying reading is improved. Furthermore, since this magnetic tape device independently performs reading retries, there is also the effect that no wasted time is caused to the host.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing details of the writing section of the above embodiment, and FIG.
The figure shows an example of the structure of a data block written on the magnetic tape in the second embodiment, and FIG. 4 is a block diagram showing details of the reading section of the second embodiment. In the figure, 1: host, 2: magnetic tape device, 3: writing section, 4: writing head, 5: magnetic tape, 6: reading head, 7: reading section, 8: switching circuit, 9, 10, 1
2, 14, 23, 24° 26. 31, 34: Data signal line, 11/recording circuit, 13: Inspection waiting signal generation circuit, 15
, 17: Control signal line, 16: Data number counting circuit, 18
: Arrow indicating tape starting end direction, 19: Segnon l', 2
0: segment data, 21: error check code, 22: switching circuit, 25 temporary storage circuit, 27: FT raw circuit. 28: segment inspection circuit, 29, 33, 35: control signal 1'f line, 30: error information holding circuit, 32: switching control circuit. Applicant: Nippon Telegraph and Telephone Public Corporation Agent

Claims (1)

[Scope of Claims] A check code generation circuit that inputs a series of block data and generates an error check code for each segment data constituted by the number of pieces of data; a data number counting circuit that outputs a OFF # control signal for each data number input; a switching circuit that inputs the input signal and the error check code and selects and outputs one or the other according to the switching control; and the switching circuit. and a recording circuit that converts the original input data output by the converter and the error check code into a recording current and supplies it to the write head, and converts the input block data and the error check code for each segment data of the data onto a magnetic tape. With a writing part to write. 11) A reproducing circuit that reproduces and outputs the signal read by the read head from the recording magnetic tape into a digital signal; a segment inspection circuit that inspects segment data for errors;
an error information holding circuit that holds the test results output from the segment test circuit; and a switching circuit that manually selects and selectively outputs the 1q raw data output from the reproduction circuit and the output data of the temporary storage circuit described below. , a cutting control circuit that controls the switching of the switching circuit based on the output of the error information holding circuit, and a temporary storage circuit that temporarily stores l blocks of data output from the switching circuit, is stored in the temporary storage circuit block by block, and in a re-reading attempt when there is an error in the segment data in the block, h of the segment data related to the segment with the error among the newly read block data is converted to the v
J, a reading section for updating the erroneous segment data by supplying the data to the temporary storage circuit via the e4 circuit.