JP2002056634A - Device and method for reproducing data - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten time needed for retry processing more than in the conventional manner by applying, for instance, a tape streamer for performing backup of the data of a server, etc., about a data processor, a data recording method and a data reproducing method. SOLUTION: Data for prescribed blocks are stored in a memory by combining reproduced data in which data whose error is hard to be corrected are detected with repeatedly reproduced data so as not to include the data whose error is hard to be corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data reproducing apparatus and a data reproducing method, and can be applied to, for example, a tape streamer for backing up data in a server or the like. According to the present invention, data of a predetermined block is stored in a memory by combining data by reproduction in which error-correctable data is detected and data by repetitive reproduction so as not to include data that is difficult to correct. In addition, the time required for the retry process can be shortened as compared with the related art.

[0002]

2. Description of the Related Art Conventionally, in a tape streamer,
At the time of reproduction, the retry process is repeated as necessary, so that, for example, desired data can be backed up with high reliability by using it for backup of a server or the like.

That is, in a tape streamer, data to be recorded is divided into predetermined blocks, and an error correction code in a product code format is added. Further, the tape streamer outputs these data and the error correction code to the recording head in a predetermined order, and records these data by forming recording tracks sequentially and diagonally on the magnetic tape.

On the other hand, during reproduction, a reproduction signal obtained from a reproduction head is subjected to signal processing to reproduce data recorded on a magnetic tape. Further, the data reproduced in this manner is subjected to error correction processing using an error correction code added at the time of recording,
If the data cannot be reproduced correctly,
The data that could not be correctly reproduced is reproduced again by the retry processing.

The tape streamer inputs and outputs data to and from a host device via a memory having a bank structure, thereby performing such recording / reproducing processing and further retry processing in a plurality of error correction processing units. Is executed in units of.

[0006]

By the way, if the time required for such retry processing can be shortened,
It is considered that a substantial data transfer rate can be improved and processing such as backup can be executed quickly, and it is considered that usability of this type of magnetic recording / reproducing apparatus can be further improved.

The present invention has been made in view of the above points, and is intended to propose a data reproducing apparatus and a data reproducing method capable of shortening the time required for retry processing as compared with the prior art. is there.

[0008]

According to the first or fourth aspect of the present invention, the present invention is applied to a data reproducing apparatus or a data reproducing method to reproduce data which is difficult to correct in a predetermined block. Then, the reproduction of the data of the block is repeated, and the data by the reproduction in which the data whose error is difficult to correct is detected and the data by the repeated reproduction are combined so as not to include the data whose error is difficult to correct. Store data in memory.

If data of a predetermined block is stored in a memory by combining data by reproduction in which data for which error correction is difficult is detected and data by repeated reproduction,
Even when data that is difficult to correct errors is detected in the repeated reproduction, data without bit errors can be stored in the memory unless the data that is difficult to correct errors is the same data. As a result, even if data that is difficult to correct errors is detected in repeated playback,
Correct data can be stored in the memory and output to the host device, and the time required for retry processing can be shortened by that much.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(1) Configuration of First Embodiment (1-1) Overall Configuration FIG. 1 is a perspective view showing a backup system according to an embodiment of the present invention. This backup system 1
Is configured by arranging a tape streamer 3 and the like on a large console 2. That is, this backup system 1
The tape streamer 3, the power supply unit 4, and the CPU unit 5 are sequentially arranged from the lower side of the front, and the transport mechanism 6 of the tape cassette is arranged on the rear side.

The power supply unit 4 supplies power to each part of the backup system 1 and the CPU unit 5
Controls the operation of the entire backup system 1. The tape streamer 3 records data from a host computer on a tape cassette loaded by the transport mechanism 6, reproduces the data recorded on the tape cassette, and outputs the data to the host computer.

The transport mechanism 6 is configured so that a plurality of tape cassettes can be stored in the shelf 6A. Under the control of the CPU unit 5, the tape cassette held in the shelf 6A is transported and loaded into the tape streamer 3. Conversely, the tape cassette discharged from the tape streamer 3 is transported to the original shelf 6A. For this reason, the transport mechanism 6 is provided with an elevator 6B that is movable in the vertical direction of the console 2 and a tape cassette mounted on the elevator 6B to take in and out a tape cassette between the shelf 6A and a tape cassette between the elevator and the tape streamer 3. And a hand block 6C for putting in and taking out.

FIG. 2 is a block diagram showing the CPU unit 5 together with peripheral components. In the CPU unit 5,
The host computer interface (host computer IF) 5A is, for example, a SCSI (Small Computer S).
The host computer 8 is connected to the host computer 8 by a system interface, and takes in commands and data to be recorded from the host computer 8 and outputs them to the internal bus BUS. Status data, reproduced data, and the like are output to the host computer 8.

The streamer interface (streamer IF) 5B is connected to the tape streamer 3 by, for example, SCSI, and outputs a predetermined control command output to the bus BUS and data to be recorded to the tape streamer 3, and vice versa. The status data output from the tape streamer 3 and the reproduced data are received from the tape streamer 3 and output to the internal bus BUS.

The control panel 5D is a console 2
And receives various operations by the operator, and notifies the CPU 5C of the operations by the operator via the internal bus BUS. The driver 5E drives the elevator 6B and the hand block 6C under the control of the CPU unit 5C.

The CPU 5C controls a whole operation of the backup system 1 in response to a command from the host computer 8 by securing a work area in the memory 5F and executing a predetermined processing procedure. That is, when an access command is input from the host computer 8, it instructs the tape streamer 3 to record and reproduce a tape cassette. At this time, if the access command from the host computer 8 is for a tape cassette different from the tape cassette loaded in the tape streamer 3, the transport mechanism 6 is controlled to load the corresponding tape cassette into the tape streamer 3. When a format of a so-called virgin tape is instructed by the operator, the tape cassette is loaded into the tape streamer 3 under the control of the transport mechanism 6, and the tape streamer 3 is instructed to perform an initialization process.

(1-2) Configuration of Tape Streamer FIG. 3 is a plan view showing the front and back of the tape streamer 3. The tape streamer 3 has an insertion port 3A formed in the front (FIG. 3A) so that a tape cassette can be inserted into and discharged from the insertion port 3A. The tape streamer 3 is provided with connectors for various connections on the back surface, so that the tape streamer 3 can be directly connected to the host computer 8 without the CPU unit 5, for example.

(1-2-1) Format of Tape Streamer FIG. 4 is a schematic diagram showing a format of a recording track by the tape streamer 3. Tape Streamer 3
In (2), longitudinal tracks are respectively formed above and below the magnetic tape 10, and oblique tracks are formed between the longitudinal tracks. Here, one of the upper and lower longitudinal tracks is assigned to the controller track 10A, and a control signal for tracking control is recorded. The other longitudinal track is ID track 1
0B, and information for managing the diagonal track is recorded in a management table.

On the other hand, an oblique track is formed by sequentially arranging a set of recording tracks with positive and negative azimuth angles. Each diagonal track is formed so as to be divided into two by a substantially central portion, and a preceding recording track of a set of recording tracks has a tracking control part for tracking control at this central divided portion. An area TP in which a pilot signal is recorded is formed.

Further, as for the diagonal track, one track set is formed by two sets and four recording tracks, and this track set is formed as a unit. A track set ID used for identifying each track set is set in each track set, and this track set ID is assigned to a part of information to be recorded on the ID track 10B. As the track set ID, a physical track set ID that simply increases in all track sets and a logical track set ID that simply increases except for dummy, EOD, and the like are set. The track set ID is S
The time code is converted into a time code by MPTE and recorded on the ID track 10B.

Each diagonal track is allocated to the A track, B track, C track, and D track corresponding to each channel of the recording / reproducing system from the leading side of the track set.

The track set includes a user track set used for recording user data, a tape mark track set assigned to a tape mark indicating a file delimiter, and an EOD (End Of D) indicating an end of data.
ata) A distinction is made between a track set, a dummy track set forming a dummy track, and the like.

FIG. 5 is a schematic diagram showing the relationship between the track set thus formed and the ECC block as an error correction processing unit. The tape streamer 3 divides user data or the like to be used for recording in predetermined block units and adds an error correction code to form an ECC block. In the tape streamer 3, data of eight ECC blocks is allocated to one track set. At this time, each of the ECC blocks indicated by the numerals 0 to 7 is divided into four equal parts in the direction of outer parity and assigned to each track, whereby the tracks are interleaved and recorded. In the data assigned to each track, the arrangement is changed and the data is interleaved and recorded.

FIG. 6 is a schematic diagram showing the ECC block. One ECC block is assigned user data of 77 × 190 bytes, and a 27-byte outer parity is generated for a 77-byte data string, and this outer parity is added to the data string. After an additional 2 × 104 byte block ID is added,
Block I in the direction orthogonal to the outer parity
A 12-byte inner parity is generated for a 192-byte data string including D, and the inner parity is added to the data string.

As a result, the ECC block is formed by adding an error correction code in a product code format and adding a 4 × 104 byte synchronization pattern SYNC. Here, the block ID is an identification ID of the ECC block, and the synchronization pattern SYNC is a specific pattern indicating the start of the ECC block.

Thus, in the tape streamer 3, 7
One ECC block is formed by allocating 7 × 190 bytes of user data and the like, and eight ECC blocks are further formed.
The assignment of blocks to one track set results in 1170 in one track set.
40 bytes of user data and the like can be assigned.

FIG. 7 is a schematic diagram showing the data structure of 117040 bytes allocated to this one user track set. One track set has a format ID of 4 bytes at the beginning. Here, the format ID is an ID for format identification, and in this embodiment, a value of a value FFFF0000h that configures one track set by four diagonal tracks is described.

Subcodes are assigned to the following 136 bytes, tables such as VSIT, VIT, and BST, which will be described later, user data track sets, identification data of tape mark track sets, and logical track set ID
And so on, and data for managing the track set is recorded.

The number of bytes obtained by subtracting the data length of the block management table from the subsequent 116884 bytes is allocated to recording of user data and the like. When assigning user data to this area, if the area cannot be filled with user data, dummy data is assigned.

The block management table is set to a maximum of 4096 bytes. Here, the tape streamer 3 is configured to be able to record and reproduce data in units of blocks of a set of track sets, and the block management table records a table used for managing these blocks. Further, in the track set, the next 12 bytes are allocated to reservation, and the remaining 4 bytes are allocated to EOD (End Of Data) indicating the end of one track set.

The tape streamer 3 records user data using a track set as a basic unit in this way, and records various management data.

FIG. 8 is a schematic diagram showing the entire layout of the magnetic tape 10. The magnetic tape 10 is a physical magnetic tape 10 excluding a leader tape connected to a reel.
A recording start position LBOT (Logical Beginning Of Tape) is set on the side on which the magnetic tape 10 has traveled a predetermined distance from the start end PBOT (Physical Beginning Of Tape), and a similar physical end PEOT (Physical End Of Tape).
f Tape), a recording end position LEOT (Logical End Of Tape) is set on the scanning start end side of the magnetic tape 10.
Various data are recorded on the magnetic tape 10 between the recording start position LBOT and the recording end position LEOT, so that the magnetic tape 10 is used in a region near the leader tape where the error rate is relatively easy to deteriorate. . The magnetic tape 10 forms one physical volume between the recording start position LBOT and the recording end position LEOT.

The magnetic tape 10 has a recording start position LBOT
A run-up area is formed for a predetermined distance, and the magnetic tape running system can be servo-locked in the run-up area. Therefore, the magnetic tape 10
Oblique tracks are sequentially formed from this run-up area.

On the magnetic tape 10, a VSIT (Volume Set table) is recorded following the run-up area, and the first physical track set ID for recording the VSIT is set to 0ID. Here, in the VSIT, various data for managing the logical volume between the recording start position LBOT and the recording end position LEOT are recorded. That is, VS
IT is the volume name of this magnetic tape, the file name recorded on the magnetic tape, and the V assigned to each file.
The physical track set ID and the like of the IT are recorded, so that the tape streamer 3 can access the VSIT so that the magnetic tape 10 can be identified. Further, each file recorded on the magnetic tape 10 and the recording position of each file are recorded. And so on. Where VS
One IT is formed by one track set (1 ID), and the same content is repeatedly recorded ten times to ensure high reliability.

On the magnetic tape 10, a VSIT retry area for 90 IDs is formed following the VSIT recording area. As a result, if necessary, the VSIT is re-recorded in this retry area to perform a recovery process or the like. It has been made executable.

Further, the magnetic tape 10 is formed so that a position margin band is subsequently formed for a predetermined ID, so that even if the VSIT is updated, the recorded data in the subsequent area is not affected at all. The magnetic tape 10
The area between the position margin band and the recording end position LEOT is allocated to the area of the logical volume.

FIG. 9 is a schematic diagram showing logical volumes assigned to this logical volume area. In the magnetic tape 10, data is recorded in file units with a tape mark TM being a file delimiter code interposed therebetween (FIG. 9A), and each file is configured by blocks. (FIGS. 9 (B) and (C)).

In the tape streamer 3, the DIT (Directory Information Table) and E
A unit including an OD (End Of Data) constitutes one logical volume. Here, the DIT is a table for managing one logical volume to which the DIT is allocated, and one length is formed by 40 IDs. DIT
As shown in FIG. 9 (D), the same content by this 40 ID is repeatedly recorded seven times, so that high reliability can be ensured.

Each of the DITs is assigned the run-up area described above in FIG. 8 at the beginning, so that the servo system can be locked. In addition, a position margin band is arranged on the rear side, so that the VIS
As in the case of T, even if updated, the recorded data in the subsequent area is not affected at all.

DIT, as shown in FIG.
VIT (Volume Information Table) by D, 1ID
(Bad Spot Table) by LID, LID by 1ID
T (Logical ID Table), FIT by 20 ID (File
Information Table), 1ID UIT (User Inf)
ormation Table) is set. The DIT is set so that the remaining 16 IDs are reserved.

Here, in the VIT, the physical track set ID is recorded in the VSIT, whereby the VIT can be accessed with reference to the VSIT recording, and further, the entire DIT can be accessed. In the VIT, a logical track set ID is set so as to match the physical track set ID. VI
T is assigned the volume label of the logical volume to which the DIT is assigned, the first physical track set ID of the user track set, and the last physical track set ID.

The BST is assigned position information of an area (hereinafter referred to as a bat spot) which is set to be unusable by the tape streamer 3 due to a scratch or the like on the magnetic tape 10. That is, in the tape streamer 3, when a bit error that is difficult to correct is generated by the read-after-write and retry processing at the time of recording, the data after this area is recorded again on the magnetic tape. In the tape streamer 3, for data newly recorded on the magnetic tape in this manner, an area where this data should be originally recorded is defined as a bad spot. In the BST, the physical track set ID at the start end and the physical track set ID at the end of such a bad spot are recorded.

The LIDT (Logical ID Table) is used for high-speed search for each block, and data of a file number, a physical track set ID, and a block number are recorded for every 200 logical track set IDs. As a result, the tape streamer 3 can roughly detect the position of the block to be accessed and search for the head at a high speed.

The FIT is formed by recording a physical track set ID of a tape mark and a block number of each block. The UT is information indicating whether or not the volume has been updated. Status data indicating whether or not the volume has been updated is set to FFFFFFFFh before updating and 000000 after updating.
00h.

(1-2-1) Schematic Configuration of Tape Streamer FIG. 10 is a block diagram showing a tape streamer 3 according to such a format. In the tape streamer 3, the SCSI interface (SCSIIF) 2
1 is connected to the CPU unit 5 by a SCSI interface, and is directly connected to the host computer when the CPU unit is not used. The SCSI interface 21 inputs user data to be recorded and outputs it to the memory controller 22, and outputs reproduced data output from the memory controller 22 to the host computer. Further, the SCSI interface 21 notifies a command from the CPU unit 5 and the host computer 8 to the main CPU unit 23 via the memory controller 22. On the contrary, it receives status and the like output from the main CPU via the memory controller 22 and outputs the status and the like to the host computer 8 and the CPU unit 5.

The memory controller 22 temporarily stores user data and the like input via the SCSI interface 21 in the buffer memory 24, and further stores the data stored in the buffer memory 24 in accordance with processing of a subsequent ECC encoder (ECCENC) 25. Output at the specified timing. The memory controller 22 has a main CPU for data of the block management table, DIT, and the like.
The corresponding data is input from the unit 23 and the buffer memory 2
4 and output to the ECC encoder 25.

On the other hand, at the time of reproduction, the memory controller 22 uses these ECC decoders (ECCDEC) at a timing synchronized with the processing of the ECC decoder 26.
The user data and the like output from 26 are temporarily stored in the buffer memory 24, and the stored user data is output to the SCSI interface 21. Further, in the above-described DIT or the like, the data output from the ECC decoder 26 is output to the main CPU unit 23. Regarding the error detection result input together with the user data, the main C
Notify the PU unit 23.

The buffer memory 24 processes user data sequentially input in a bank structure in units of capacity corresponding to the above-mentioned predetermined number of track sets.
This constitutes a bank memory. As a result, in the tape streamer 3, the recording / reproducing process is executed and the retry process is executed using one bank configured in the buffer memory 24 as a processing unit. As a result, in a track set, when recording user data with a data amount less than one bank, a dummy track set in which dummy data is recorded in place of the user data is formed.

The ECC encoder 25 forms the ECC block described above with reference to FIG. 6 by generating and adding an error correction code to data output from the memory controller 22 and by adding a synchronization pattern and the like. Further, the ECC encoder 25 outputs the data of the ECC block by a plurality of systems corresponding to the arrangement of the magnetic heads. Further, at this time, the ECC encoder 25 outputs these data in a predetermined order, thereby executing inter-track interleaving and word interleaving processing.

The equalizer 28 converts the data output from the ECC encoder 25 into a serial data string by a plurality of systems corresponding to the arrangement of the recording heads, and further modulates the data by a method suitable for recording on the magnetic tape 10. As a result, the equalizer 28 generates a drive signal for driving the recording head, and drives the recording head mounted on the rotating drum 29 with this drive signal.

The rotary drum 29 is provided with a recording head of a predetermined system and a reproducing head for scanning the scanning trajectory of the recording head, and rotates at a predetermined rotation speed under the control of the servo circuit 31. This enables Tape Streamer 3
Are formed so that diagonal tracks are sequentially formed on the magnetic tape 10 running at a predetermined speed to record user data and the like, and that the recording result can be monitored by a reproducing head.

The equalizer 30 receives a reproduction signal from a reproduction head mounted on the rotating drum 29 during recording and reproduction, and performs waveform equalization and demodulation processing on the reproduction signal to thereby record data recorded on the magnetic tape 10. To play.

The ECC decoder 26 uses the equalizer 3
The output data of 0 is fetched, and error correction processing is performed using an error correction code added during recording. ECC decoder 2
6 outputs the user data and the like obtained by the error correction processing to the memory controller 22 together with the error detection result as the error correction processing result. As a result, the tape streamer 3 outputs data recorded on the magnetic tape 10 to the host computer 8 via the buffer memory 24, and data such as VIST can be obtained by the main CPU 23 as necessary. I have.

The ECC decoder 26 notifies the error detection result obtained in this way to the main CPU unit 23 via the buffer memory 24.
Under the control of the U unit 23, processing such as retry can be executed as needed. ECC decoder 2
6 simply executes an error detection process at the time of recording user data, records the resulting error detection result together with the user data and the like in the buffer memory 24,
This makes it possible to determine whether or not the data recorded in the read-after-write processing has been correctly reproduced. The ECC decoder 26 stores such an error detection result in the buffer memory 24 by setting a corresponding error flag.

In this way, the main CPU 23 secures a work area in the random access memory (RAM) 33 and executes a predetermined processing procedure in response to a command input via the SCSI interface 21. The tape streamer 3 is mainly composed of a unit, controls the operation of the entire tape streamer 3, and notifies the host computer 8 of the status as needed. In this process, the buffer memory 24 is accessed as necessary to obtain information such as VSIT and DIT reproduced from the magnetic tape 10, and further, based on this information,
The operation of the drive system and the like is controlled. After recording the user data, the entire operation is controlled so that the corresponding DIT and VSIT are rewritten.

System controller (syscon) 34
Mainly controls the operation of the mechanical system of the tape streamer 3 by exchanging data with the main CPU unit 23 executed via the dual port RAM (DP-RAM) 35. That is, in the tape streamer 3, the sensor 37
Is disposed at a cassette insertion slot or the like.
The servo circuit 3 detects whether or not 0 can be loaded.
Notify 1. The capstan motor (M) 36 runs the magnetic tape 10 under the control of the servo circuit 31.
The fixed head 38 is connected to the longitudinal track 10 of the magnetic tape 10.
A and 10B and the longitudinal tracks 10A and 1B.
The reproduced signal of 0B is output to the servo circuit 31.

The servo circuit 31 drives a predetermined drive system based on the detection result of the tape cassette by the sensor 37 to execute processing such as loading and unloading of the tape cassette, and loading and unloading of the magnetic tape 10. And the like. The servo circuit 31 drives the rotary drum 29 to rotate, and controls the rotation speed of the capstan motor 36 based on the determination of the reproduction result of the CTL track 10A based on the rotation phase of the rotary drum 29, thereby performing tracking control. Execute the processing of During reproduction, the servo circuit 31 executes these tracking control processes with reference to a tracking control pilot signal assigned to an oblique track of the magnetic tape 10.

On the other hand, when the magnetic tape 10 is initialized, the servo circuit 31 drives the fixed head 38 while the magnetic tape 10 is running at a predetermined running speed, so that the magnetic tape 10 10A and 10
Form B. The servo circuit 31 includes a fixed head 38
The obtained reproduction signal is processed, the management data is reproduced, and the management data is output to the system controller 34. The time code assigned to the management data is obtained from a time code recorder (TCR) 4.
Output to 0.

In the initialization process, the time code recorder 40 sequentially generates a time code and outputs the time code to the servo circuit 31. The servo circuit 31 uses the time code and various data output from the system controller 34. The management data is generated by the fixed head 3
8 is driven. On the other hand, at the time of recording and reproduction, the time code obtained from the servo circuit 31 is replaced with the track set ID.
And output.

The system controller 34 controls the operation of the servo circuit 31 and also outputs a track set ID output from the time code recorder 40 via the main CPU 23 to the ECC encoder 25 and the like.

Interface CPU (IFCPU) 4
1 exchanges data with the main CPU unit 23 via the DP-RAM 42, thereby the shelf 6A, the elevator 6
In B, information on the tape cassette can be obtained, and further, data communication with another computer system is possible.

That is, in the tape streamer 3, the reader / writer arranged on the shelf 6A or the like uses the antenna (AN
T) 44 to I located on the back of the tape cassette 45
A radio wave is transmitted to the C tag 46, and this radio wave
When a response is obtained from the IC tag 6, various information relating to the tape cassette 45 is transmitted to and received from the IC tag.

The display CPU 49 inputs and outputs data transmitted and received between the IC tags via the memory label interface 47 to and from the interface CPU 41. The display CPU 49 displays various data on a predetermined display screen according to data input via the interface CPU 41. This display is, for example, display of information on a tape cassette loaded in the tape streamer 3.

The SIO 50 is, for example, RS-232C,
It is a serial interface such as RS-422, and transmits and receives maintenance information to and from external devices. The Ethernet IO is an Ethernet (registered trademark) interface, and is connected to a predetermined network so that various information can be transmitted and received.

(1-2-1) Retry Process With such a configuration, the tape streamer 3 can directly input the user data output from the host device to the SCSI interface 21 or send the user data output from the SCSI interface 21 through the CPU unit 5. The user data is stored in the buffer memory 24. Further, the ECC encoder 25 adds a product code type error correction code to the user data stored in the buffer memory 24 in a predetermined error correction processing unit, and the eight error correction processing units correspond to four recording tracks. A to D are recorded on the magnetic tape 10 by one track set. At the time of reproduction, a reproduction signal obtained from the magnetic head is processed to obtain reproduction data, error-corrected by the ECC decoder 26, accumulated in the buffer memory 24, and output to the host device.

During recording, the tape streamer 3 monitors the amount of user data stored in the buffer memory 24 by the main CPU 23, and when the user data for 40 track sets is accumulated in the buffer memory 24, In response to the notification from the CPU 23, the system controller 34 drives the servo circuit 31 and the like to record the user data for this 40 track set on the magnetic tape 10. As a result, the tape streamer 3 becomes 4
One track set of user data is processed by one bank, and the user data is sequentially recorded on the magnetic tape 10.

On the other hand, at the time of reproduction, the system controller 34 sets the buffer memory 24 every time user data for one track set is stored in the buffer memory 24.
Check the error detection result stored in. When the user data for the continuous 40 track sets can be correctly reproduced by this monitoring, the system controller 34 entrusts the processing of the user data stored in the buffer memory 24 to the main CPU 23, and the main CPU 23 By replacement, the buffer memory 24
Is transmitted to the host device for 40 track sets. As a result, the tape streamer 3 reproduces and outputs data recorded on the magnetic tape 10 by processing user data in units of data for 40 track sets even during reproduction.

The system controller 34 monitors the error processing result of the user data in this manner.
When a bit error for which error correction is difficult occurs, a retry process is executed. In the retry process, the system controller 34 waits for the reproduction of the user data of the 40 track set, rewinds the magnetic tape 10, and then returns to the 40 including the portion where the bit error has occurred.
Replay the user data for the track set.

In this retry processing, the memory controller 22 outputs the output data of the ECC decoder 26 by the reproduction in which the error-correctable data is detected and the retry processing so as not to include the data whose error correction is difficult. And the output data of the ECC decoder 26 is stored in the buffer memory 24.

More specifically, the memory controller 22 sets the track set as a rewrite unit, and outputs the output data of the ECC decoder 26 stored in the buffer memory 24 in accordance with the error detection result recorded in the buffer memory 24 in this rewrite unit. ECC decoder 2 for retrying
6 is selectively updated by the output data. As a result, the memory controller 22 uses only the track set where the bit error has occurred among the user data for the 40 track sets including the part where the bit error has occurred and is stored in the buffer memory 24 as the reproduction data related to the retry. The contents of the buffer memory 24 are updated.

As a result, as shown in FIG. 11, the tape streamer 3 compares the reproduced data image with the magnetic tape 10 in units of track sets as shown in FIG. Even if the error occurs (FIGS. 11A to 11C), unless a bit error is repeated in the same track set, as shown in FIG. (FIG. 12 (A1) to (C1)). Note that, in FIGS. 11 and 12, the case where the reproduction is correctly performed is indicated by a code OK, and the case where a bit error occurs is indicated by a code NG. Also, in FIG. 12, the reproduction data of each track set is represented by one rectangle in comparison with FIG. 11, and changes in the contents of the buffer memory in the conventional tape streamer are compared with FIGS. 12 (A2) to (C2). Show. In the conventional tape streamer, the entire contents of the buffer memory are rewritten by repetition of reproduction, and when bit errors which are difficult to correct are generated by such repetition of reproduction, they are eventually output to the host device. It becomes difficult to accumulate possible reproduction data in the buffer memory, and it becomes necessary to repeat many retries as compared with this embodiment.

In this case, the system controller 3
When the retry is repeated and the user data successfully reproduced in the buffer memory is accumulated for the set of 40 tracks, the retry process is terminated, and the transmission of the data held in the buffer memory 24 is performed by the main CPU.
Leave it to 23.

If bit error data is recorded in the buffer memory 24 even after the retry is repeated a predetermined number of times, the system controller 34 also ends the retry process in this embodiment. In this case, an error is notified to the host device via the main CPU 23.

(2) Operation of the First Embodiment In the above configuration, in the backup system 1 (FIGS. 1 and 2), the tape cassette housed in the shelf 6A by the management of the CPU unit 5 is a tape streamer. 3
, Then loaded and sequentially fixed head 3
8, the ID track 10B and the CTL track 10A, which are the longitudinal tracks of the magnetic tape 10, are recorded on the magnetic tape 10 (FIGS. 4 and 10). As a result, the track set ID based on the time code is recorded on the magnetic tape 10 as one of the management data in units of one track set. After that, after the magnetic tape 10 has been rewound, the V
The SIT is recorded (FIG. 8), whereby the volume name of the tape cassette is recorded, and the initialization process is completed. The tape cassette initialized in this way is
Under the control of the CPU unit 5, it is conveyed and stored at a predetermined position on the shelf 6A.

On the other hand, when data backup is instructed from the host computer 8, if the tape cassette corresponding to the tape streamer 3 is not loaded,
Under the control of the CPU unit 5, the corresponding tape cassette is taken out from the shelf 6A and set on the tape streamer 3. The tape cassette previously loaded in the tape streamer 3 is discharged from the tape streamer 3 and stored in the shelf 6A.

When the tape cassette is loaded into the tape streamer 3 in this manner, the tape streamer 3 loads the magnetic tape 10 to reproduce the VSIT, and accesses the file specified by the host computer 8 from the VSIT. The magnetic tape 10 is made to run as much as possible. That is, when a file is to be recorded on the magnetic tape 10 for the first time, D
The IT is recorded, and subsequently the data output from the host computer 8 is sequentially recorded on the magnetic tape 10. Also, when appending to a previously recorded file, the DIT of the corresponding file is reproduced based on the VSIT recording, and this DIT
The end of the last block is detected from the IT, and data input from the host computer 8 is recorded sequentially from this end. When data reproduction is instructed from the host computer 8, the position of the corresponding file is set to VSIT.
Then, the DIT is accessed and the data recorded on the magnetic tape 10 is reproduced according to the recording of the DIT (FIG. 9).

At the time of this recording, the user data output from the host computer is transmitted to the ECC encoder 2
After adding an error correction code in the product code format to the user data sequentially input by the step 5 (FIG. 6), the tracks are interleaved by the four tracks constituting one track set (FIG. 5), and between the words. The data is sequentially recorded on the magnetic tape 10 by interleaving. When the user data is accumulated in the buffer memory 24 for a set of 40 tracks, the user data is output to the ECC encoder 25 and recorded on the magnetic tape 10.

On the other hand, at the time of reproduction, a reproduction signal obtained from the magnetic head is processed by the equalizer 30 to obtain reproduction data, and the ECC decoder 26 performs error correction processing. As a result, the user data recorded on the magnetic tape 10 is reproduced, and the reproduced data is recorded in the buffer memory 24 together with the error detection result as the error correction processing result.

Based on the error detection result, the presence or absence of a bit error is determined by the system controller 34 in units of one track set based on the error detection result.
When stored in the buffer memory 24, the main CPU 23
Is output to the host device via the SCSI interface 21 under the control of.

When a bit error for which error correction is difficult is detected in such a reproducing process, the tape streamer 3 stores user data for 40 track sets in the buffer memory 24 under the control of the system controller 34. After that, the retry process starts,
The user data for this 40 track set is reproduced from the magnetic tape 10 again.

In the retry processing, the tape streamer 3 (FIGS. 11 and 12) generates a bit error in accordance with the error detection result for the user data for 40 track sets already recorded in the buffer memory 24. The contents of the buffer memory 24 are selectively updated with the user data related to the retry only for the user data of the track set. Thus, in the tape streamer 3, the output data of the ECC decoder 26 by reproduction in which the data of which error is difficult to detect and the output data of the ECC decoder 26 by this retry processing are combined so that the data which is difficult to correct is not included. In combination, output data for 40 track sets is accumulated in the buffer memory 24.

As a result, data without bit errors can be stored in the buffer memory 24 in a much shorter time than in the conventional processing in which the contents of the buffer memory are completely rewritten each time a retry is performed. As a result, for the user data for 40 track sets, the accumulation of data without bit errors is completed and the retry process is completed, so that the time required for the retry can be significantly reduced as compared with the conventional case. it can. Accordingly, the amount of time required for the retry can be shortened in this way, and the substantial data transfer speed can be improved as compared with the related art.

In the tape streamer, if a bit error occurs even after the retry is repeated a predetermined number of times, the retry is stopped. In the case where user data is stored in the buffer memory 24 by a combination of reproduction data in each reproduction as in this embodiment, a case where a bit error occurs even if such retry is repeated a predetermined number of times is considered. The number of times can be reduced as compared with the related art. Accordingly, the error retry efficiency can be improved as compared with the related art, and the error rate of the entire apparatus can be improved.

(3) Effects of the First Embodiment According to the above configuration, the data obtained by reproducing the data in which the error-correction is detected and the data obtained by repeating the reproduction are performed so that the data in which the error-correction is difficult is not included. By storing data of a predetermined block in the memory in combination with the data, the time required for the retry process can be reduced as compared with the related art.

(4) Second Embodiment In a tape streamer according to this embodiment, as shown in FIG. 13 in comparison with FIG. 11, two recording / reproducing systems using A channel Ach and B channel Bch. A channel Ach and B channel Bch
, Successive track sets are alternately generated by the recording system according to, and the continuous track sets are alternately reproduced (FIG. 13A). The tape streamer according to the present embodiment has the same configuration as the tape streamer 3 according to the first embodiment except that the configuration regarding the two systems of recording and reproducing systems is different.

That is, at the time of reproduction, the tape streamer accumulates the reproduction data of such two reproduction systems for a set of 40 tracks in the buffer memory and outputs it to the host device. At this time, if a bit error is detected, a retry process is executed. During this retry, the tape streamer changes the running phase of the magnetic tape 10 until A
The track set assigned to the reproduction system of channel Ach is reproduced by the reproduction system of B channel Bch,
The track set previously assigned to the B channel Bch playback system is played back by the A channel Ach playback system (FIG. 13B). Further, based on the error detection result recorded in the buffer memory, the contents of the buffer memory are updated in the same manner as the tape streamer 3 described above.

As a result, the tape streamer is
The retry process can be completed in a much shorter time than in the embodiment. That is, the bit error in this type of magnetic recording / reproducing apparatus has a feature that often depends on the magnetic head. If the allocation of the reproducing system is switched as in this embodiment, the bit error in FIG. As a result, as shown in FIG. 14, the probability that data that has been reproduced due to a bit error can be correctly reproduced is increased, and the retry process is completed in a shorter time than that in the first embodiment. Can be.

According to the second embodiment, in addition to the configuration according to the first embodiment, the running phase of the magnetic tape is changed at the time of retry, so that the first embodiment is modified. In comparison with this, the time required for retry can be further reduced.

(5) Other Embodiments In the above embodiment, the user data having a bit error is also stored in the buffer memory.
At the time of retry, it has been described that the data in which such a bit error has occurred is updated so that repeated reproduction data is combined and stored in a memory so as not to include data for which error correction is difficult. Not limited to this, by selectively recording reproduction data in which a bit error does not occur in a buffer memory so that repeated reproduction data is combined and stored in a memory so as not to include data that is difficult to correct. Is also good.

Further, in the above-described embodiment, the case where error-corrected reproduced data is stored in the buffer memory and output is described. However, the present invention is not limited to this. The present invention can be widely applied to a configuration in which data is stored in a buffer memory and then subjected to error correction processing using a C2 code.

In the above-described embodiment, the case where the retry process is executed in units of 40 track sets has been described. However, the present invention is not limited to this, and the retry unit may be variously set as necessary. can do.

In the above-described embodiment, a case has been described in which one track set, which is a unit of eight error correction processing, is combined with repeated reproduction data and stored in the memory. However, the present invention is not limited to this, and it is also possible to combine repeated reproduction data in units of recording tracks, error correction units, and the like, and store the data in the memory.

Further, in the above embodiment, the case where the present invention is applied to the tape streamer in combination with the transport mechanism has been described, but the present invention is not limited to this.
For example, the present invention can be widely applied to a tape streamer configured to be directly connected to a host computer.

In the above-described embodiment, the case of recording data of a computer has been described. However, the present invention is not limited to this, and can be widely applied to, for example, processing of video signals and audio signals. it can.

[0096]

As described above, according to the present invention, the output data obtained by the reproduction in which the error-correctable data is detected and the output data obtained by the repeated reproduction are combined so as not to include the data which is difficult to correct. By accumulating the output data for a predetermined block in the memory, the time required for the retry process can be shortened as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a backup system according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the backup system of FIG. 1;

FIG. 3 is a front view and a rear view showing a tape streamer of the backup system of FIG. 1;

FIG. 4 is a schematic diagram illustrating a recording format by the tape streamer of FIG. 3;

FIG. 5 is a schematic diagram for explaining inter-track interleaving in the tape streamer of FIG. 3;

FIG. 6 is a schematic diagram illustrating an ECC block in the tape streamer of FIG. 3;

FIG. 7 is a schematic diagram for explaining a track set in the tape streamer of FIG. 3;

8 is a schematic diagram for explaining a physical volume of the entire magnetic tape in the tape streamer of FIG. 3;

9 is a schematic diagram for explaining each volume in the tape streamer of FIG. 3;

FIG. 10 is a block diagram showing the tape streamer of FIG. 3;

FIG. 11 is a schematic diagram for explaining a retry in the tape streamer of FIG. 3;

12 is a schematic diagram illustrating a change in the contents of a buffer memory corresponding to the processing in FIG. 11;

FIG. 13 is a schematic diagram for explaining a retry in a tape streamer according to a second embodiment of the present invention.

FIG. 14 is a schematic diagram showing changes in the contents of a buffer memory in the tape streamer of FIG. 13;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Backup system, 3 ... Tape streamer, 5 ... CPU unit, 6 ... Transport mechanism, 8 ... Host computer, 10 ... Magnetic tape, 23 ... Main CPU unit, 24 ... Buffer memory, 25 ...... ECC
Encoder, 26 ECC decoder

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 5/09 361 G11B 5/09 361F

Claims (4)

[Claims] In a data reproducing apparatus for reproducing and outputting data recorded on a magnetic tape, when data that is difficult to correct in a predetermined block is reproduced, reproduction of the data in the block is repeated, and the data in the block is difficult to correct. The data of the block is stored in a memory by combining the data obtained by the reproduction in which the error-correctable data is detected and the data obtained by the repeated reproduction so as not to include the data, and the data stored in the memory is stored in the memory. A data reproducing device for outputting to a host device. 2. The method according to claim 1, wherein the data stored in the memory is selectively rewritten in a predetermined rewriting unit, so that the data obtained by the reproduction in which the hard-to-correct error data is detected is not included so that the hard-to-correct error data is not included. 2. The data reproducing apparatus according to claim 1, wherein the data of the block is stored in the memory in combination with data obtained by the repeated reproduction. 3. The data reproducing apparatus according to claim 1, wherein the repetitive reproduction is executed by changing a phase in which the magnetic tape runs. 4. Reproducing data recorded on a magnetic tape,
In the method of reproducing data output via a memory, when data for which error correction is difficult in a predetermined block is reproduced, the reproduction of the data of the block is repeated, and the error correction is performed so as not to include the error-correctable data. Storing data of the block in a memory by combining the data obtained by the reproduction in which the proper data is detected and the data obtained by the repeated reproduction, and outputting the data stored in the memory to a host device. How to play.