JP2002352516A - Multi-track magnetic tape device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve data restoration ability. SOLUTION: When there are three error tracks among which there is an error track from which data cannot be read out due to a preamble section (yes of step 209), data is forcibly read out from one of the error tracks from which data cannot be read out due to the preamble section (step 210) by using a synchronizing signal recorded in the preamble section of the track from which data can be normally read out. As a result, the number of error tracks is decreased into two tracks to make ECC(error correction code) correction possible (step 203).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-track magnetic tape device for simultaneously recording and reproducing digital data on a plurality of tracks on a magnetic tape.

[0002]

2. Description of the Related Art FIG. 4 shows a schematic configuration of a serpentine multi-track magnetic tape device having an error correction function. The multi-track magnetic tape device (hereinafter, simply referred to as a magnetic tape device) includes a supply reel 1, a take-up reel 2, a magnetic head 3, and a motor 4, and moves the magnetic tape 5 forward (F) and reverse ( R)
Digital data is simultaneously recorded and reproduced on a plurality of tracks on the magnetic tape 5 using the magnetic head 3. That is,
Group codet recording method (GCR method)
To record and play back digital data.

[Write Format] FIG. 5 shows a format for writing digital data to the magnetic tape 5. The magnetic tape 5 has, for example, nine physical tracks (TR1 to TR9).
9, digital data is recorded simultaneously. Track TR
The recording of digital data in 1 to TR9 is performed in block units. One recording block BL includes a preamble section S1,
It comprises a data section S2 and a postamble section S3.

In the preamble section S1, a synchronization signal (preamble) used for reading data from the data section S2 is written. This synchronization signal is transmitted to the data section S2.
Is written into the preamble section S1 as a pattern signal of the maximum frequency of the data to be written to the preamble S1. Data part S2
, An error correction code (ECC) used for error correction and a cycle redundancy check (CRC) used for error checking are written in addition to required backup data.

[Reading of data] FIG.
FIG. 3 is a diagram illustrating a configuration when data is read out from the device 1; Note that, similarly to the track TR1, data is simultaneously read from the tracks TR2 to TR9 with the same configuration. In FIG. 6, the data recorded on the track TR1 is read by the magnetic head 3 and
And enters the peak detection circuit 7.

FIG. 7A shows a head output voltage from the magnetic head 3 to the preamplifier 6 (head output waveform in a modulation method (NRZ code) at zero and no inversion input). In this case, a preamble portion S1 is provided at the head of the recording block BL on the track TR1, and a synchronization signal is written in the preamble portion S1. First, the synchronization signal written in the preamble portion S1 is read from the magnetic head 3. The peak detection circuit 7 detects the positive and negative peaks of the head output voltage from the magnetic head 3 via the preamplifier 6, and outputs a rectangular wave signal (see FIG. 7B) corresponding to the recording data to the PLL circuit ( Phase locked loop circuit) 8 and a window comparator 9.

The PLL circuit 8 generates a PLL clock signal (see FIG. 7 (c)) phase-locked to the frequency of the data written in the data section S2 from the synchronizing signal written in the preamble section S1. A window signal having a wider pulse width is generated from the PLL clock signal (FIG. 7).
(Refer to (d)), and give it to the window comparator 9. The window comparator 9 compares the window signal from the PLL circuit 8 with the rectangular wave signal from the peak detection circuit 7 corresponding to the recording data after the preamble portion S1, and records the recording data in the pulse width (window) of the window signal. The level of the rectangular wave signal corresponding to the error correction circuit 1
Send to 0.

The error correction circuit 10 includes a recording block BL
When all the data are obtained, an error check by CRC is performed, and the error check result is sent to the CPU 11.
Send to If the track TR1 is an error track (defective track), the other tracks TR2 to T
Error correction (ECC correction) is performed using the ECC in the same recording block BL of R9. Also, the error correction result in this case is the same as the error check result.
Send to U11.

The CPU 11 has other tracks TR2 to TR
The error correction circuit 10 for R9 also outputs the track TR
The error check result and the error correction result are sent in the same manner as from the error correction circuit 10 for 1. If the number of error tracks is less than two (YES in step 802 shown in FIG. 8), the CPU 11 confirms the success of the ECC correction in the error track (YES in step 803), and checks the data from the recording block BL. After reporting a status indicating that the reading has succeeded to the host device 12 (step 804), the process ends normally (step 805). Normally, out of nine tracks, if the number of tracks from which data cannot be read for some reason is within two tracks,
Data can be restored by ECC correction. In addition,
If at least one ECC correction has failed (step 803)
NO), all the data read from the recording block BL are discarded, and a status indicating that the data read has failed is reported to the higher-level device 12 (step 808), and then the process ends abnormally (step 809).

If the number of error tracks is three or more (NO in step 802), the CPU 11 reads data from the recording block BL again (retry read: step 807). This retry lead
Repeat until the error track is within 2 tracks,
If the number of error tracks does not fall within two tracks even if the number of retries reaches a predetermined number n (YES in step 806), all data read from the recording block BL is discarded, and data reading fails. After reporting the status to the host device 12 (step 808), the process ends abnormally (step 809).

[0011]

However, in the above-described conventional magnetic tape device, if there are three or more error tracks, all data read from the recording block BL is discarded regardless of the cause of the error tracks. As a result, the data recovery ability was low.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a multi-track magnetic tape device capable of improving data recovery ability.

[0013]

In order to achieve the above object, the present invention relates to a multi-track magnetic tape apparatus, which includes an error track from which data cannot be read due to a preamble portion. Using the synchronization signal recorded in the preamble section of the track from which data could be read normally, data was forcibly removed from the data section of the error track from which data could not be read due to the preamble section. It is intended to be read out. Also, if data cannot be read normally even by this forced read,
The phase of a window signal generated from a synchronization signal recorded in a preamble portion of a track from which data can be normally read is shifted, and data is forcibly read from the data portion of the error track again. Things.

According to the present invention, the error track whose data could not be read due to the preamble portion was used by using the synchronization signal recorded in the preamble portion of the track from which the data could be read normally. The data is forcibly read from the data portion of, and the number of error tracks is reduced.

For example, if there are three error tracks and there is an error track from which data cannot be read due to the preamble part, the error track is recorded in the preamble part of the track from which data can be read normally. If the data is forcibly read from one of the error tracks from which data could not be read due to the preamble portion using the synchronization signal, the number of error tracks is reduced, and the number of error tracks is reduced. Becomes

Further, there are four or more error tracks, among which error tracks from which data cannot be read due to the preamble portion, and within two error tracks not due to the preamble portion. In this case, it is possible to read data due to the preamble portion until the number of error tracks becomes two by using the synchronization signal recorded in the preamble portion of the track from which data could be read normally. If data is forcibly read from the failed error track, the number of error tracks is reduced to two tracks.

If the number of error tracks is two, for example, if the number of tracks on the magnetic tape is nine, data can be restored by error correction such as ECC, and data read from a recording block can be restored. Is avoided, and the ability to recover data is improved.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a main part of an embodiment of a multi-track magnetic tape device according to the present invention, and is a diagram showing a configuration when data is read from a track TR1. Note that, similarly to the track TR1, data is simultaneously read from the tracks TR2 to TR9 with the same configuration. 1, the same reference numerals as those in FIG. 6 denote the same or equivalent components.

In this embodiment, a lock completion signal indicating the completion of the phase lock in the PLL circuit 8 and a PLL clock signal are supplied to the CPU 11, and the CPU 11
A window signal is generated from the clock signal and sent to the window comparator 9. In addition, the CPU 11 performs a processing operation according to the flowchart of FIG.

The CPU 11 receives an error check result and an error correction result from the error correction circuit 10 for the tracks TR1 to TR9. If the number of error tracks is within two tracks (YES in step 202), the ECC correction in the error tracks is performed. Is confirmed (YES in step 203), and the status indicating that the data has been successfully read from the recording block BL is changed to the host device 12.
(Step 204), and the process ends normally (step 205). If at least one error correction has failed (NO in step 203), all the data read from the recording block BL are discarded, and a status indicating that the data reading has failed is reported to the higher-level device 12 (step 203). 213), and terminate abnormally (step 214).

If the number of error tracks is three or more (NO in step 202), the CPU 11 rereads data from the recording block BL (retry read: step 207). This retry lead
Repeat until the error track is within 2 tracks,
If the number of error tracks does not fall within two tracks even when the number of retries reaches a predetermined number n (YES in step 206), the process proceeds to step 208.

In step 208, the CPU 11
It is checked whether or not there is an error track from which data cannot be read due to the preamble part in the error track. Whether or not there is an error track caused by the preamble portion is determined by a lock completion signal from the PLL circuit 8. That is, it is checked whether or not the track is a phase-locked track by the lock completion signal, and the track whose phase is not locked is determined as an error track caused by the preamble portion.

When the CPU 11 determines that there is an error track caused by the preamble portion (YES in step 208), it determines whether the number of error tracks including the error track caused by the preamble portion is within three tracks. Is checked (step 209). If the number of error tracks is less than three (YES in step 209), data is forcibly read from one of the error tracks caused by the preamble portion (step 210). This forced read will be described later.

If there is no error track due to the preamble portion in the error tracks (NO in step 208), or if there are four or more error tracks (NO in step 209), the CPU 11
Discards all data read from the recording block BL, reports a status indicating that data reading has failed to the upper-level device 12 (step 213), and ends abnormally (step 214).

[Forced Read] The CPU 11 executes step 2
In step 10, data is forcibly read from one of the error tracks caused by the preamble portion using the synchronization signal recorded in the preamble portion of the track from which the data could be normally read. That is, a window signal generated from a synchronization signal recorded in a preamble portion of a track from which data can be normally read is provided to a window comparator 9 of an error track caused by the preamble, and data demodulation is forcibly attempted. . In this case, the error track caused by the preamble portion is 3
One case, two cases, one case. If there are two or more error tracks due to the preamble portion, any one of them is set as an error track to be forcibly read.

When the forced read succeeds (step 21)
0), that is, data is normally read from the target error track of the forced read caused by the preamble portion, and the error correction circuit 10 for the error track is read.
When the CPU 11 receives an error check result indicating that data has been read normally from the CPU, the CPU 11 causes the error correction circuit 10 for the remaining two error tracks to perform ECC correction, and determines that the ECC correction on the error track has succeeded. After confirmation (YES in step 203), a status indicating that data reading from the recording block BL was successful is reported to the host device 12 (step 204), and the process ends normally (step 205).

When the forced read fails (step 21)
(NO at 0), the CPU 11 offsets the window signal to the window comparator 9 of the error track to be forcibly read to the window comparator 9 back and forth by a predetermined amount as shown in FIGS. 3 (e) and 3 (f) (step 212). That is, the phase of the window signal is shifted by a predetermined amount in the + direction and the-direction, and the forced read from the target error track is performed again (retry read: step 212). If the forced read is not successful even if the number of retries reaches a predetermined specified number m (Y in step 211)
ES), the CPU 11 discards all the data read from the recording block BL, and reports a status indicating that the data reading has failed to the host device 12 (step 2).
13), terminate abnormally (step 214).

As described above, according to the present embodiment, even if three error tracks are found in the first error check, if there are error tracks due to the preamble portion, data can be read normally. The data is forcibly read from the error track caused by the preamble portion using the synchronization signal recorded in the preamble portion of the resulting track. As a result, the number of error tracks is reduced and the number of error tracks can be corrected.
A situation in which the data becomes a track and all data read from the recording block BL is discarded is avoided, and the data recovery capability is enhanced.

In the above-described embodiment, the forced reading is performed when there are three error tracks and there is an error track caused by the preamble portion, but when there are four or more error tracks, It is also possible to apply to.

For example, in the flowchart shown in FIG. 2, instead of step 209, a step of determining whether or not the number of other error tracks not caused by the preamble portion is two or less is provided. If the number of error tracks is not within two tracks, that is, if there are three or more tracks, the process proceeds to step 213. If the number of other error tracks not caused by the preamble portion is within two tracks, the process proceeds to step 210 until the total number of error tracks becomes two.
The forced read from the error track caused by the preamble portion is repeated.

As a result, even if four or more error tracks are found in the first error check, there are error tracks due to the preamble part in them, and the number of other error tracks not due to the preamble part is within two. If so, the data is forcibly read from the error track caused by the preamble portion using the synchronization signal recorded in the preamble portion of the track from which the data could be normally read. The repetition of the forced read reduces the number of error tracks to two ECC-correctable tracks, avoids a situation in which all data read from the recording block BL is discarded, and further enhances the data recovery capability. .

[0032]

As apparent from the above description, according to the present invention, when there is an error track from which data cannot be read due to the preamble portion, the preamble of the track from which data can be read normally Using the synchronization signal recorded in the section, data was forcibly read from the data section of the error track where data could not be read due to the preamble section. It is possible to reduce the number of found error tracks to the number of error tracks such as ECC that can be corrected, avoid a situation in which all data read from a recording block is discarded, and improve the data recovery ability. Becomes possible. If the data cannot be read normally even by the forced read, the phase of the window signal generated from the synchronization signal recorded in the preamble portion of the track from which the data was successfully read is shifted. Since the data is forcibly read from the data portion of the error track again, even if the window signal used for the forced read is slightly shifted, the data is reliably read from the data portion of the error track caused by the preamble portion. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a block diagram (track TR) showing a main part of an embodiment of a multi-track magnetic tape device according to the present invention.
FIG. 2 is a diagram extracting and showing a configuration when data is read from No. 1).

FIG. 2 is a flowchart showing a processing operation at the time of data reading performed by a CPU in the multi-track magnetic tape device.

FIG. 3 is a time chart showing signal waveforms at the time of reading data from a track TR1 in the multi-track magnetic tape device.

FIG. 4 is a diagram showing a schematic configuration of a serpentine multi-track magnetic tape device having an error correction function.

FIG. 5 is a diagram showing a format for writing digital data to a magnetic tape.

FIG. 6 is a diagram extracting and showing a configuration for reading data from a track TR1 of a conventional multi-track magnetic tape device.

FIG. 7 is a time chart showing a signal waveform when reading data from a track TR1 in a conventional multi-track magnetic tape device.

FIG. 8 is a flowchart showing a processing operation at the time of data reading performed by a CPU in a conventional multi-track magnetic tape device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Supply reel, 2 ... Take-up reel, 3 ... Magnetic head, 4 ... Motor, 5 ... Magnetic tape, 6 ... Preamplifier, 7
... peak detection circuit, 8 ... PLL circuit, 9 ... window comparison circuit, 10 ... error correction circuit, 11 ... CPU, 12 ... host device, TR1-TR9 ... track, BL ... recording block, S1 ... preamble section, S2 ... data Section, S3 ... Postamble section.

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Claims (6)

[Claims] 1. A multi-track magnetic tape apparatus for simultaneously recording and reproducing digital data on a plurality of tracks on a magnetic tape, using a synchronization signal recorded in a preamble section of the track, using a data section of the track. Data reading means for reading data recorded in the preamble section, and if there is an error track from which data cannot be read due to the preamble section, the data is recorded in the preamble section of the track from which data can be normally read. An error track forced reading means for forcibly reading data from a data portion of an error track whose data could not be read due to the preamble portion using a synchronization signal. Track magnetic tape unit. 2. A multi-track magnetic tape apparatus for simultaneously recording and reproducing digital data on a plurality of tracks on a magnetic tape, using a synchronization signal recorded in a preamble section of the track, using a data section of the track. Data reading means for reading data recorded in the preamble section, and if there is an error track from which data cannot be read due to the preamble section, the data is recorded in the preamble section of the track from which data can be normally read. Error track forced reading means for forcibly reading data from the data part of the error track from which data could not be read due to the preamble part using a synchronization signal; and error track forced reading means. If data cannot be read normally, The error track which forcibly reads data from the data portion of the error track again by shifting the phase of the window signal generated from the synchronization signal recorded in the preamble portion of the track from which the data can be read normally. A multi-track magnetic tape device comprising re-compulsory reading means. 3. A multi-track magnetic tape device for simultaneously recording and reproducing digital data on a plurality of tracks on a magnetic tape, using a synchronization signal recorded in a preamble portion of the track, and using a synchronization signal recorded in a preamble portion of the track. Data reading means for reading the data recorded in the memory, and three error tracks from which the data cannot be read. If there is an error track from which the data cannot be read due to the preamble portion, the data is normally read. Using the synchronization signal recorded in the preamble part of the track from which data could be read,
A multi-track magnetic tape device, comprising: error track forced reading means for forcibly reading data from one of the error tracks from which data could not be read due to the preamble portion. 4. A multi-track magnetic tape apparatus for simultaneously recording and reproducing digital data on a plurality of tracks on a magnetic tape, using a synchronization signal recorded in a preamble section of the track, and using a synchronization signal recorded on the track, Data reading means for reading the data recorded in the memory, and three error tracks from which the data cannot be read. If there is an error track from which the data cannot be read due to the preamble portion, the data is normally read. Using the synchronization signal recorded in the preamble part of the track from which data could be read,
Error track forced reading means for forcibly reading data from one of the error tracks from which data could not be read due to the preamble portion; and the error track forced reading means can also read data normally. If not, the phase of the window signal generated from the synchronization signal recorded in the preamble portion of the track from which the data could be read normally is shifted, and the data is forcibly again forced out of the data portion of the error track. A multi-track magnetic tape device, comprising: an error track re-forced reading unit for reading data from the disk. 5. A multi-track magnetic tape apparatus for simultaneously recording and reproducing digital data on a plurality of tracks on a magnetic tape, using a synchronization signal recorded in a preamble section of the track, the data section of the track being used. Data reading means for reading data recorded in the preamble section, and there are four or more error tracks from which data cannot be read, among which error tracks from which data cannot be read due to the preamble section. If the number of other error tracks not caused by the error is within two tracks, the number of error tracks is reduced to two using the synchronization signal recorded in the preamble portion of the track from which data can be normally read.
A multi-track magnetic tape device comprising: an error track compulsory reading means for forcibly reading data from an error track from which data could not be read due to the preamble section until a track is formed. 6. A multi-track magnetic tape apparatus for simultaneously recording and reproducing digital data on a plurality of tracks on a magnetic tape, using a synchronization signal recorded in a preamble section of the track, the data section of the track being used. Data reading means for reading data recorded in the preamble section, and there are four or more error tracks from which data cannot be read, among which error tracks from which data cannot be read due to the preamble section. If the number of other error tracks not caused by the error is within two tracks, the number of error tracks is reduced to two using the synchronization signal recorded in the preamble portion of the track from which data can be normally read.
Error track forced reading means for forcibly reading data from an error track from which data could not be read due to the preamble portion until a track is reached; and the error track forced reading means can also read data normally. If not, the phase of the window signal generated from the synchronizing signal recorded in the preamble portion of the track from which the data could be read normally is shifted, and the data portion of the error track is again forcibly forced out. A multi-track magnetic tape device comprising: an error track re-forced reading unit for reading data.