JPH0845244A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To simplify processing, such as reading out and updating, of a user management table by holding management information stored in a memory means in a data buffer and executing reading out or rewriting of management information via a random access s means. CONSTITUTION:A host computer issues a header access command to access the position of the management table on a sub-memory 10 to a main CPU l of an interface section 12 as a first command in the case the processing to access to a management table is started. As a result, the access mode of bank memories 5, 6 is set at a DIT access mode. A command to read out the file management region of the memory 10 and write the region into the memories 5, 6 is issued as the second command of the host computer to the CPU 1. The CPU 1 writes the DIT read out of the memory 10 into the memories 5, 6. The interface section 12 supplies the data to be changed in the DIT written into the memories 5, 6 to the host computer to change only the returned data to be changed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a magnetic recording / reproducing apparatus for converting data supplied from a host computer into a specific format and recording it on a magnetic tape, or supplying reproduced data to the host computer. Regarding

[0002]

2. Description of the Related Art The American standard ANSI DD-1 format (ANSI) for recording, which has been under discussion
X3B5). This format not only records data on a cassette tape but also defines in detail a data structure for file management and an error detection method for improving an error rate so as to be suitable for computer peripherals.

This DD-1 format data recorder is connected to a host computer by a SCSI interface via an interface unit.
Since this interface unit is recognized as a magnetic tape device by the host computer,
It has a formatter function that creates a file format on tape and exchanges data on it.

The applicant of the present invention has uniquely developed a tape format that can be realized as a data recorder or the like suitable for a computer peripheral corresponding to the DD-1 format. In this tape format, 1 from the physical tape start position (hereinafter referred to as "PBOT").
A logical tape start position (hereinafter referred to as “LBOT”) is set at a position passing through a dummy area of 0 meters, and after a predetermined run-up section is provided from the position of LBOT, it is determined whether the loaded tape is valid as a tape format. Volume set information table (hereinafter referred to as “VSI
"T". ) Is provided. The VSIT manages the entire tape, and one VSIT has an area of 100 ID.

A directory information table (hereinafter referred to as "DIT") for file management is provided at a position passing from VSIT through a dummy area. The DIT records a management table of the position and number of tape marks indicating the delimiters of data written in the user data area. In addition, the DIT has an area that can be freely accessed by the user and a user file management table that manages the contents of the user data area can be constructed. One DIT has an area of 100 ID. The DIT can also record update information as a tape volume.

In addition to the tape format originally developed by the applicant of the present invention, there is a tape format that has a management table open to the user, such as 8 mm tape streamer manufactured by Exabyte Corporation.

FIG. 34 shows such a conventional user file management table access. When the user file management table is to be realized by a normal sequential access device, the tape layout is as shown in FIG. The access operation is shown below. FIG.
In 4, the access pointer 342 during the writing process is located at the writing point of the user data 431 during the normal reading or writing process of the user data area. In this state, the head is moved to the user data area 341 to create a file.

Here, when updating the management table 340, the host computer issues a locate command for moving the position of the head to the data recorder as the first command. As a result, as a preparation for accessing the management table, the head is moved so that the access pointer 343 of the management table search process is located at the head of the management table 340.

Next, the host computer issues a read command as a second command to the data recorder to read the data of the capacity of the management table. Thereby, the access start processing of the management table is performed. The access pointer 344 for starting the management table read and ending the management table reading process at the end position of the management table
The lead ends when the head moves to position. Here, in the access operation of the management table,
In a normal sequential access device in which the head accesses the tape, the management table cannot be written in 1ID units, and therefore the entire management table is stored in the memory of the host computer. In the memory of the host computer, the data at the position indicated by the access pointer 345 at the management table update processing position of the downloaded data is updated.

The host computer issues a locate command for moving the position of the head as a third command to the data recorder. As a result, the access pointer 343 of the management table search process is set as the preparation for writing the management table on the tape.
The head is moved so that it is located at the beginning of 0. next,
As a fourth command, the host computer issues a write command as a fourth command for writing data of the management table size. As a result, the head writes the management table updated on the memory of the host computer on the tape.

The host computer issues a locate command for moving the position of the head to the data recorder as a fifth command. As a result, the access pointer 346 for returning to the normal access position and starting the process by the changed management table is changed to the user data area 341.
Move the head so that it is located at the beginning of.

As described above, in order to change the data in the management table 340, the host computer needs to supply five commands. Further, the host computer needs a memory having a capacity for the management table. In this case, several tens of megabytes of memory are required.

In an access method using a sequential access device, in which a magnetic tape is accessed by a head, in order to actually read a desired read position, skipping or updating the target table from the head position of the management table Had to read the previous data once to the host computer, update only that location, and write all that data to tape.

[0014]

As described above, in the conventional magnetic recording / reproducing apparatus, since the access method by the sequential access device is used when accessing the user file management table, the reading of the management table, Operations such as update and addition become complicated. When these operations are performed, the amount of data read and written by the host computer becomes much larger than the actually required amount of data read and written. Further, there is a disadvantage that the sequence for reading and updating the management table is increased and the process is complicated.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a magnetic recording / reproducing apparatus capable of simplifying processes such as reading and updating of a user information management table.

[0016]

As shown in FIGS. 1 to 33, a magnetic recording / reproducing apparatus of the present invention converts data supplied from a data supply source through a data buffer 5 or 6 into a specific format. Then, in a magnetic recording / reproducing apparatus which records on a magnetic tape, reproduces the data recorded on the magnetic tape, and supplies the data via a data buffer 5 or 6 to a data supply source, during normal operation, before recording or reproducing operation. In the preprocessing to be performed, the management information storage means 10 for storing the management information 22 of the magnetic tape provided at the head portion of the magnetic tape created based on the format is provided, and the management information stored in the management information storage means 10 is provided. 22
Data is stored or reproduced through the data buffers 5 and 6 based on the above, and when the management information 22 is read or rewritten, the management information 22 stored in the management information storage means 10 is held in the data buffers 5 and 6. However, the random access means 1, 5 and 6 for randomly accessing the management information 22 is provided to read or rewrite the management information 22.

The magnetic recording / reproducing apparatus of the present invention is shown in FIG.
As shown in FIG. 33, in the above description, the random access means 1, 5, 6 are
A command for changing the management information 22 is supplied from a data supply source.

The magnetic recording / reproducing apparatus of the present invention is shown in FIG.
As shown in FIG. 33, in the above description, the random access by the random access means 1, 5, and 6 is to specify the position to access the management information 22 and the data length.

The magnetic recording / reproducing apparatus of the present invention is shown in FIG.
As shown in FIG. 33, in the above description, only the management information 22 of the portion rewritten by random access by the random access means 1, 5, 6 is recorded on the magnetic tape.

[0020]

According to the present invention, when the management information 22 is read or rewritten, the management information 22 stored in the management information storage means 10 is held in the data buffers 5 and 6, and the management information 22 is randomly accessed. Since the random access means 1, 5 and 6 are provided to read or rewrite the management information 22, it is not necessary to read all of the management information 22 sequentially when the management information 22 is read or updated, and the management information 22 is read or rewritten. Only the management information 22 of the power portion can be directly random-accessed, and the management information 22 specific to the application can be easily constructed.

Further, according to the present invention, in the above, the random access means 1, 5, 6 issues a change command of the management information 22 from the data supply source to the data buffers 5, 6 for storing the management information 22. Since the supply of the management information 22 is not necessary for the data supply source, it is sufficient to provide the data supply source with a memory only for the capacity of the management information 22 of the portion to be read or rewritten. Can be accessed.

Further, according to the present invention, in the above-mentioned random access by the random access means 1, 5, and 6, since the access position and the data length for the management information 22 are designated, the data buffers 5 and 6 are stored. Only the portion of the stored management information 22 to be read or rewritten can be directly random-accessed.

Further, according to the present invention, since only the management information 22 of the portion changed by random access by the random access means 1, 5 and 6 is recorded on the magnetic tape in the above, the moving length of the magnetic tape is reduced. Since the length is shortened, the wear of the magnetic tape is reduced and the recording / reproducing operation can be performed at high speed.

[0024]

1 is a block diagram showing the configuration of a control unit of an embodiment of a magnetic recording / reproducing apparatus according to the present invention. The magnetic recording / reproducing apparatus of the present invention uses a tape format which is a recording format originally developed by the present applicant.
This tape format can be realized by a data recorder or the like suitable for a computer peripheral corresponding to the DD-1 format. In this example, particularly when reading or rewriting management information provided based on the tape format. In addition, random access to the management information written when the tape is loaded facilitates high-speed access to the management information.

As shown in FIG. 1, the interface unit 12 connects a host computer (not shown) and a tape-format data recorder by, for example, a SCSI interface.

The interface unit 12 is an interface device having a tape stream emulation for controlling the data recorder like a tape streamer such as MT. The interface unit 12 has a formatter function of creating a tape format on a tape and exchanging data on the tape format.

The interface section 12 converts the data transferred from the host computer into a tape format and controls the data recorder. The interface unit 12 includes a bank memory 5 as a data buffer that temporarily holds data via a data line when supplying data from the host computer to the data recorder or when supplying data from the data recorder to the host computer. It has a bank memory 6. The bank memories 5 and 6 exchange data during normal operation, but write management information when reading or rewriting management information to facilitate random access from the host computer. The data recorder (not shown) has a magnetic tape running system such as a motor for running a magnetic tape and a reel, and a recording / reproducing system such as a modulating circuit, a demodulating circuit, and a recording / reproducing head for recording / reproducing signals to / from the magnetic tape. are doing.

The main CPU 1 is a control unit for receiving commands from the host computer via a control line and controlling the entire interface. The sub CPU 3 receives a command from the main CPU 1 and controls a data recorder or the like via a control line. Dual port RAM2 is the main CPU
1 is a memory for communication between the sub CPU 1 and the sub CPU 3.

The bank switch 4 is a switch for switching between the bank memory 5 and the bank memory 6. DMA
C7 is a direct memory access controller that receives commands from the main CPU 1 and controls the bank memory 5. The DMAC 8 is a direct memory access controller that receives commands from the sub CPU 3 and controls the bank memory 6.

The timer 9 has seven VSITs or DIs.
This is for generating a random number from which the order of reading any one of T is obtained. For example, a timer started at the time of factory shipment may be used. By setting a unique value based on a random number, the main CPU 1 controls the bank memories 5 and 6 so as to read any one of the seven VSITs or DITs according to the random number. The sub-memory 10 is an area for storing a firmware work area and a tape mark management table which is a delimiter for files. The management information is written in the sub memory 10 when the tape is loaded, the data recorder is normally operated based on the management information in the normal operation, and the management information is stored in the buffer memory 5 when the management information is read or rewritten. , 6 to facilitate random access. The PIO 11 designates the value of the DIP switch for designating the optimum transfer rate of data transfer between the interface unit 12 and the data recorder. Based on this data, the main CPU 1 sets a value in the internal transfer rate switch to determine the transfer rate with the data recorder.

FIG. 3 shows formats and tracks on a magnetic tape of an embodiment of the magnetic recording / reproducing apparatus according to the present invention. In FIG. 3A, VSIT 32 is provided from the head of the magnetic tape 30 through the dummy area 31. V
The SIT 32 determines whether the magnetic tape 30 is valid as a tape format. A DIT 34 is provided from the VSIT 32 through the dummy area 33.
The DIT 34 manages the position and the number of tape marks indicating the delimiters of the data written in the user data area 36. A user data area 36 is provided from the DIT 34 through a dummy area 36. An EOD 37 indicating the end position of data is provided at the end of the user data area 36. In FIG. 3B, the tracks recorded on the magnetic tape 30 in an oblique direction are provided with user data 39 and subcodes 38 indicating the attributes of the user data 39.

Details of the tape format used for the interface unit 12 and the data recorder will be described below. The specifications not specified in this tape format are the American standard ANSI X3.1.
75-1990.

FIG. 4 shows a logical format of a tape format magnetic tape. The recording area is an area between a logical tape start position (hereinafter, referred to as “LBOT”) and a logical tape end position (hereinafter, referred to as “LEOT”). The LBOT refers to a position 10 meters from the physical tape start position (hereinafter referred to as “PBOT”). LEOT indicates 15 meters before the physical tape end position (hereinafter referred to as "PEOT"). Both PBOT and PEOT indicate the start and end points of the physical tape.

Between PBOT and LBOT and between LEOT and PEOT are invalid areas, and other LBOs
The area from T to LEOT is called a recording area. The VSIT 40 is provided from the position of LBOT via the run-up area 44. A DIT 41 is provided after the VSIT 40 via a margin 47 and a run-up region 45. DIT4
A user data area 42 is provided after 1 through a margin 48 and a run-up area 46. After the user data area 42, the area from the EOT approximate position (hereinafter referred to as “NEOT”) to LEOT is effectively called the tape end area 43. In this case, the data (helical data, control data, and annotation data) in the invalid area is meaningless in terms of tape compatibility. Here, even if some data exists, it is not regarded as valid data, and the physical track set ID
Alternatively, other data need not exist.

As shown in FIG. 5, the recording area has a valid data area and an invalid data area. In the valid data area, the physical track set ID continuously and monotonically increases. There are three types of valid data areas: a ramp area that is an approach area until the data track is locked, a table that is an area of a table for tape management information, and user data in which user data is recorded.

In the invalid data area, there are margin areas 56 and 57 for providing a margin for not deleting the valid data behind the table when updating the table or the like.
The volume set information table 50 (hereinafter referred to as “VSIT”) is opened from the place where at least 1024 track set IDs are opened as the run-up area 53 behind the 6976 ID which is the track set ID of the LBOT.
Begins. The track set ID of that VSIT50,
8000 ID. VSIT50 is 7 for each 100 ID
Since it is written individually, it occupies 700 IDs.

Following VSIT50, the directory information table 51 (hereinafter referred to as "DIT") is opened from a position where at least 1024 track set IDs are opened as a margin area 56 (1.5 m) and a run-up area 54 from 8700 ID.
Say. ). Since seven DIT51 are written for each 100 ID, they occupy 700 ID.

Following the DIT 51, a margin area 57 (1.
5m), the user data area 52 starts from a place where at least 1024 track set IDs are opened as the run-up area 55. Then, as shown in FIG.
The recording data area 52 ends at the approximate position NEOT.

In FIG. 5, the effective tape end position area between NEOT and LEOT is the area required for the operation for ending the tape. The amount depends on the implementation.

FIG. 6 shows a logical track of the tape format. The first 4 bytes are reserved area 60 (111
11111) ₁₆ filled. The contents of the sub-code data 61 are shown in FIGS. 14, 18, 20, 22, 24, 25, 26, 27 and 2 described later for each data type.
8 and 29. FIG. 30 shows a summary of all subcodes. The definition of each subcode data is shown in FIG. Subcode parameters are shown in Figs.
2, 33.

In FIG. 6, the subcode data 61 is
Write 100-byte subcodes 65, 66 and 67 three times. The padding area 68 is the rest of the three writings.
(168 bytes), the data is undefined. FIG.
4, 18, 20, 22, 24, 25, 26, 27, 2
In Nos. 8 and 29, the calculation range of the checksum (W24) is from W0 to W23. Calculate from 1 byte in units of 4 bytes.

14, 18, 20, 22, 24, 25,
In 26, 27, 28, and 29, the most significant bit “B” of W2 is a block operable flag. When "0", the operation is disabled-the parameters W2, W3 and W4 are invalid. When "1", the operation is possible-the content has not been decided yet. The most significant bit "A" of W6 is an append file pointer, and this flag is set for the first track set ID that has been appended.

In FIGS. 24, 25, 26 and 27, W7
The most significant bit “W” of is a write retry counter operable flag. When it is "0", the operation is disabled-the write retry counter of W7 is set to (0) ₁₆ .
When "1", the operation is possible-when a write retry occurs for this track, the write retry counter of W7 is incremented. W8 to W23 are reserved words and are filled with "0".

Returning to FIG. 6, the user data 62 is user valid data, and data up to "32768 bytes" can be recorded. Padding data 6
3 indicates the remaining part of the remaining user data area 62 when the size of the user data 62 is less than “32768 bytes”, and the data is undefined. Garbage 64 is "2868 bytes" and is a reserved area, but the data is undefined.

Next, the management table will be described with reference to FIG. In the volume information table VSIT70, as shown in FIG. 7, in order to improve the reliability of the data in the management table, VSIT of 100 track set ID is repeatedly written 3 to 7 times.

The VSIT table 71 (1 track set ID) is an EOD or dummy track 72 (not shown).
It ends with (78 track set ID). If the dummy track 72 ends, the dummy data track 7
When 2 continues for 16 track set IDs or more, it is considered as end. Repeated data uses the same data including the subcode. This is excluded when the write retry counter is valid.

The VSIT table 71 is shown in FIG.
The subcode of the VSIT table is shown in FIG. FIG.
3, W44 is the first physical track set ID number of the data area of the physical volume (tape).

W45 is the last physical track set ID number in the data area of the physical volume (tape). This becomes the physical track set ID of the EOD in the user area. W62 is the number of VITs. W65 is
This is the first physical track set ID of the VIT.

Returning to FIG. 7, the update table UT
73 (1 track set ID) is shown in FIG. The subcode of the update table is shown in FIG. This update table is a table indicating whether the attached table is being updated. For example, the update table may show "1" when the tape is loaded and "0" when the tape is unloaded. In FIG. 21, W0: Update status is (0
0000000) ₁₆ : updated, (FFFFFFF
F) ₁₆ : Update is in progress.

Returning to FIG. 7, the checksum track 75
(1 track set ID) is shown in FIG. In the calculation range, only the user data area in the logical track, which is the VSIT and UT areas, is the calculation target. One word is calculated from 4 bytes.

The DIT 80 will be described with reference to FIG. As shown in FIG. 8, the DIT 80 has a 100 track set ID in order to improve the reliability of the data in the management table.
Repeat DIT from 3 to 7 times. DI
The T table 81 ends with an EOD or dummy track (not shown). In the case of the end in the dummy track, it is considered as the end when the dummy data track continues for 16 track set IDs or more. The repeated data is
Use the same data including the subcode. This is excluded when the write retry counter is valid.

In FIG. 8, the volume information table 8
1 (hereinafter referred to as “VIT”) is shown in FIG. 15 and FIG.
6 is shown. In FIG. 16, W255 is provided with an overwrite counter, and W256 is provided with an initialization number. The VIT subcode is shown in Figure 1.
8 shows. VIT includes W4 to W43 in FIG.
And the first physical track set I of the data area area of the volume managed by this table of the physical volume (tape) shown by W44.
D number is provided.

In FIG. 15, similarly, the last physical track set ID number of the data in the data area area of the volume managed by this table of the physical volume (tape) shown in W45 is provided, and the position of the EOD is set. Indicates.

W62 is a file information table (hereinafter,
It is called "FIT". ) Is the number of tape marks registered in. W63 is the number of track sets used by the file information table FIT.

W64 represents the first UIT type. The first is the specified UIT, as shown in FIG.
Refers to. type is U when (00000000) ₁₆
IT is not used. (00000000) ₁₆ ~ (7FF
FFFFF) ₁₆ is reserved, (800000
00) ₁₆ to (FFFFFFFF) ₁₆ are vendor unique.

In the three-track bad spot table shown in FIG. 8, the bad spot physical track set ID number is written as shown in FIG. As the subcode, as shown in FIG. 18, the same VIT subtable is used. This bad spot table is a table as management information including information indicating an area of invalid data. Therefore, as shown in FIG. 8, it includes the entire management information (DIT) at the beginning of the tape. The bad spot table is a table that manages logically invalid data generated by a write retry operation or an append write operation.

As shown in FIG. 9, when writing the data "B" having the same logical track set ID "N" as the logical track set ID "N" of the data "A", the reading is invalid. The data “A” to be set is called a bad spot, that is, invalid data. In the bad spot table, the head logical track set ID “N” and the last logical track set I of this bad spot are shown.
D "N + 1" is recorded.

As shown in FIG. 17, the bad spot table is provided with the first physical track set ID number of the invalid data area. The most significant bit “U” indicates the cause of invalidation. In this case, (1) ₁₆ is set when it is invalid due to an error, and (0) ₁₆ is set when it is invalid except for an error. Similarly, the last physical track set ID number in the invalid data area is provided.

The file information table is shown in FIG. The subcode of the file information table is shown in FIG. FIG.
As shown in FIG. 9, the file information table is provided with the physical track set ID number of the tape mark and the absolute block number of the tape mark.

Returning to FIG. 8, the update table UT
86 (1 track set ID) is shown in FIG. The subcode of the update table UT is shown in FIG. This update table is a table indicating whether the attached table is being updated. The update status is (00000000) ₁₆ : updated, (FF
FFFFFF) ₁₆ : Updating is in progress.

In FIG. 8, UIT84 (64 track set ID) is a user information table. An area for data used by users to manage information. The subcode of the user information table UIT is shown in FIG. Returning to FIG. 8, the checksum track 87 (1 track set ID) is shown in FIG. The subcode of the checksum track is shown in FIG. The calculation range is V
IT, bad spot, FIT and UT areas.
Only the area of user data in the logical track is to be calculated. Calculate from 1 byte in units of 4 bytes.

Next, the order of data handling is shown in FIG.
As shown in 0, the order is byte serial. In the case of 32-bit data, it is performed in order from LSB to MSB. That is, the process is performed from W0 to W3. Even in the case of 16-bit data, the order is from LSB to MSB.
That is, the processing is performed in the order from W0 to W1. The reserve area (68 track set ID) as the dummy area 85 in the management table shown in FIG. 8 is filled with (0) ₁₆ . Write retry is not performed in the management table area.

Next, the user data track shown in FIG. 6 will be described. The user data track is
User data up to "32768 bytes" is a track that can be recorded in the user data area. As shown in FIG. 11, the data track is error-corrected by the product code of C1 and C2. The subcode of user data is shown in FIG. In FIG. 24, W2
2 has an overwrite counter and W23 has an initialization number.

FIG. 12 shows a tape format helical data track. In FIG. 12, the traveling direction of the head is oblique with respect to the traveling direction of the tape, and the helical data track 121 is formed in the same oblique direction as the traveling direction of the head. Helical data track 121
Are formed from the bottom to the top in the order from LSB to MSB. Annotation tracks 122 and 123 for recording notes are formed on the upper and lower ends of the tape 120. A control track 124 is formed on the annotation track 123 at the lower end. The control track 124 has a sync signal and a track set I.
D is recorded.

The tape mark track is used as a separator between two adjacent files. The tape mark uses one track set. The user data area of the track is undefined. The tape code subcode is shown in FIG.

EOD is a track indicating the end of recorded data. When indicating the end, the EOD must be continuous for 16 or more track set IDs. The user data area of the track is undefined. The subcode of EOD is shown in FIG.

The dummy track is used to fill the area when a continuous control track is required. The user data area of the track is undefined. The subcode of the dummy track is shown in FIG.

FIG. 2 is a diagram showing access to the user file management table in one embodiment of the magnetic recording / reproducing apparatus according to the present invention. The user file management table is a table constructed by using the user information table UIT as a user open area provided in the directory information table DIT.

Since the tape format has already been described in detail, it will be briefly described here. In FIG. 2, the recorded area 20 has, for example, 4 tracks and 1 ID.
It is an area in which only the ID to be recorded is recorded. The dummy areas 24, 25, and 26 are areas required as run-up sections for reading and writing the effective area, and dummy data is recorded therein. The VSIT 21 is an area for managing the entire tape, and since it is important, seven 100IDs are written. VS
The IT 21 functions to determine whether the loaded tape is valid as a tape format. The DIT 22 is an area that manages the contents of the user data area 23, and since it is important, seven 100 IDs are written. The DIT 22 functions to manage the position and number of tape marks written in the user data area.

First of all, when the tape is loaded, the VSI of one of the seven VSIT21 and DIT22 is
T21 and DIT22 are written in the sub memory 10 via the bank memories 5 and 6. The VSIT 21 determines whether the loaded tape is valid as a tape format. Then, the normal user data area 23
When data is being read or written in, the head moves so that the access pointer 27 during the reading and writing process is located in the user data area 23. In this state, the head is creating a file in the user data area 23. At this time, data for creating a file is exchanged on the bank memories 5 and 6.

Next, when starting the access to the management table, the host computer uses the first command as a first command for the main CPU 1 of the interface section 12 to access the position of the management table on the sub memory 10. Issue an access command. This allows
The access mode of the bank memories 5 and 6 is set to the DIT access mode. At this time, the bank memories 5 and 6 stop the normal exchange of data and give up their storage areas for writing the management table. Next, the host computer issues a read / write file management area command as a second command to the main CPU 1 of the interface unit 12 to read the file management area in the sub memory 10 and write it in the bank memories 5 and 6. At this time, the main CPU 1 writes the DIT read from the sub memory 10 into the bank memories 5 and 6.

As a second command, the host computer reads a file management area on the sub memory 10 from the main CPU 1 of the interface section 12 and writes a read / write file management area command to the bank memories 5 and 6 to issue a sub command. The management data in the DIT read from the memory 10 and written in the bank memories 5 and 6 is changed. At this time, the host computer
The position of the access pointer 28 during the DIT reading process and the data length to be changed are specified, and the data is supplied to the main CPU 1 of the interface unit 12.

The interface section 12 supplies the data to be changed in the DIT written on the bank memories 5 and 6 to the host computer, and changes only the data to be changed returned from the host computer. The data length to be changed is specified by the block length. One block is 1024 bytes. In this case, one read / write file management area command can be used to specify the read / write of management data, the change target position, and the data length. Since this operation is an operation on the bank memories 5 and 6, the head movement, the reading process from the tape, and the writing process to the tape do not occur. Therefore, the abrasion of the tape is reduced, and the recording / reproducing operation becomes faster.

Finally, when returning to normal access,
The host computer issues a normal user access mode command to the main CPU 1 of the interface section 12 as the third command to return the access mode of the bank memories 5 and 6 to the normal mode. At this time, the head moves to the position of the changed DIT data, and after writing the changed data on the tape, the head is further moved to move the access pointer 29 for starting the processing by the changed DIT to the user data area 23. Move to the beginning position.
As a result, the bank memories 5 and 6 read the changed DIT and give up its storage area for exchanging data in the normal operation. However, in the operation of the read / write file management area command for reading the file management area on the sub memory 10 to the main CPU 1 of the interface unit 12 and writing it to the bank memories 5 and 6 as the second command, in the operation of the user information management table When there is only a read operation and no write operation, the management data is not written.

As described above, in order to change the user file management table of the DIT 22, the host computer may issue three commands to the main CPU 1 of the interface section 12. Furthermore, the host computer does not need to have a memory for storing all of the DIT 22, and may have a memory having a capacity corresponding to the data length to be changed in the DIT 22. In this case, a memory of about 1 kilobyte is enough.

This makes it possible to easily build an application-specific management table for files created on the tape. This management table records the file creation date, file size, file name, and the like.

In general, an application has a structure in which a file is created on a tape and its attributes are managed by a hard disk of a host computer. In this case, the user's file is divided into a sequential access device such as a tape, and the management table is divided into a random access device such as a hard disk and a floppy disk for management. This management table needs to be randomly accessed for use in a database or the like.

Since the application used by the user has such a configuration, it is possible to correspond to the existing application by allowing random access to the user management table. Further, unlike the existing application, it is not necessary to divide the management table and the file into two media such as a tape and a hard disk.

As described above, the application is constructed so that the high speed and large capacity of the tape device are combined with the convenience of the high speed access of the random access device, the management table can be randomly accessed, and the user data can be sequentially accessed. It can be done easily. Also,
Since operations such as reading, updating, and writing of the management table are only operations on the bank memory of the interface unit 12, it is possible to perform high-speed processing by a command supplied from the host computer side.

According to the above example, DIT2 as management information
At the time of the read or rewrite operation of 2, the DIT 22 as the management information stored in the sub memory 10 as the management information storage means is held in the bank memories 5 and 6 as the data buffer, and the DIT 22 as the management information is randomly accessed. Since the main CPU 1 as the random access means and the bank memories 5 and 6 are provided to read or rewrite the DIT 22 as the management information, all of the DIT 22 as the management information is read when the DIT 22 as the management information is read or updated. Need not be sequentially read, and only the DIT 22 as the management information of the portion to be read or rewritten can be directly random-accessed, and the DIT 22 as the application-specific management information can be easily constructed.

Further, according to the above example, in the above, the main CPU 1 as the random access means and the bank memories 5 and 6 are supplied from the data supply source to the data buffers 5 and 6 which store the DIT 22 as the management information. Since the change instruction of the DIT 22 as the management information is supplied, it is not necessary to suck up all of the DIT 22 as the management information to the data supply source, and the data supply source has the capacity of the DIT 22 as the management information of the portion to be read or rewritten. It is sufficient to provide only the memory, and the DIT 22 as the management information can be easily accessed.

Further, according to the above example, in the above, the random access by the main CPU 1 as the random access means and the bank memories 5 and 6 designates the access position and the data length with respect to the DIT 22 as the management information. , Bank memories 5 and 6 as data buffers
Only the portion to be read or rewritten in the DIT 22 as the management information stored in the above can be directly random-accessed.

Further, according to the above example, only the DIT 22 as the management information of the portion changed by random access by the main CPU 1 as the random access means and the bank memories 5 and 6 is recorded on the magnetic tape in the above description. Since the moving length of the magnetic tape is shortened, the wear of the magnetic tape is reduced and the recording / reproducing operation can be performed at high speed.

In the above example, the interface section 12 is not limited to the above example, and any other user information management table corresponding to this tape format may be used. Further, as the tape format, any data recorder or streamer compatible with the ID-1 format can be realized.
It can be applied to all interfaces of the data recorder that adopts the format.

Further, as long as it is possible to determine the continuity of a certain ID corresponding to the physical ID in the data recorder, other sequential devices such as 8 mm tape, digital audio tape (DAT), and ordinary cassette are used. It can also be applied to an application that handles a large amount of data such as a database of image data using a tape device such as a tape (QIC) when a user information management table is provided on the tape.

In the variable rate buffer as a system for writing data to the data recorder,
The interface unit 12 in the above example can be replaced by providing a function of converting to this tape format.

Further, in the rack type VME bus in which data is transferred to the interface section via the VME bus and recorded in the ID-1 format by the data recorder, a function of converting to the DTF format is provided. The interface unit 12 in the example can be replaced.

In the above example, when the tape is loaded, the management information including the bad spot as the information indicating the invalid data area provided in the DIT at the beginning of the tape created based on this format is read. The management information may be updated each time writing is performed.

As described above, the header VSIT and DIT are read at the same time as the loading of the magnetic tape and the data from the host computer is written on the magnetic tape or the data on the tape is read according to the directory information on the magnetic tape. Alternatively, the latest management information may be written back to the DIT and sent back to the host computer to eject the magnetic tape.

Before the eject, the latest overwrite counter value and the initializing number are set to D.
The parameter may be stored as one parameter in IT, and when it is next loaded, the DIT may be read and at the same time, the overwrite counter and the initialization number used when writing to the magnetic tape may be set in the memory.

[0091]

According to the present invention, the random access means for holding the management information stored in the management information storage means in the data buffer and randomly accessing the management information when the management information is read or rewritten is provided. ,
Since the management information is read or rewritten, it is not necessary to read all of the management information sequentially when reading or updating the management information, and only the management information of the portion to be read or rewritten can be directly accessed randomly. Unique management information can be easily constructed.

Further, according to the present invention, in the above, the random access means supplies the management information change command from the data supply source to the data buffer storing the management information. It is not necessary to download all of the above, and the data supply source may be provided with a memory only for the capacity of the management information of the portion to be read or rewritten, and the management information can be easily accessed.

Further, according to the present invention, in the above-mentioned random access by the random access means, since the access position and the data length for the management information are designated, the read of the management information stored in the data buffer is performed. Alternatively, only the portion to be rewritten can be directly accessed randomly.

Further, according to the present invention, since only the management information of the portion which is randomly accessed and changed by the random access means is recorded on the magnetic tape in the above description, the moving length of the magnetic tape is shortened. Wear is reduced and the recording / reproducing operation can be performed at high speed.

[Brief description of drawings]

FIG. 1 is a block diagram of a control unit of an embodiment of a magnetic recording / reproducing apparatus of the present invention.

FIG. 2 shows access to a user file management table in one embodiment of the magnetic recording / reproducing apparatus of the present invention.

FIG. 3 is a diagram showing formats and tracks on a magnetic tape of an embodiment of a magnetic recording / reproducing apparatus of the present invention,
FIG. 3A shows a format on a magnetic tape, and FIG. 3B shows tracks.

FIG. 4 is a diagram showing a logical data format on a magnetic tape in a tape format.

FIG. 5 is a diagram showing a logical data format indicating a table position of a tape format.

FIG. 6 is a diagram showing a logical track of a tape format.

FIG. 7 is a diagram showing the configuration of a tape format VSIT.

FIG. 8 is a diagram showing the structure of a tape format DIT.

FIG. 9 is a diagram showing bad spots in a tape format.

FIG. 10 is a diagram showing an order of handling data in a tape format.

FIG. 11 is a diagram showing error correction of a tape format.

FIG. 12 is a diagram showing a tape format helical data track.

FIG. 13 is a diagram showing a VSIT table of a tape format.

FIG. 14 is a diagram showing a VSIT subcode of a tape format.

FIG. 15 is a diagram showing a VIT table of a tape format.

FIG. 16 is a diagram showing a VIT table of a tape format.

FIG. 17 is a diagram showing a VIT table (bad spot table) of a tape format.

FIG. 18 is a diagram showing a VIT subcode of a tape format.

FIG. 19 is a diagram showing a file information table of a tape format.

FIG. 20 is a diagram showing subcodes of a tape format file information table.

FIG. 21 is a diagram showing an update table of a tape format.

FIG. 22 is a diagram showing a subcode of an update table of a tape format.

FIG. 23 is a diagram showing checksum data of a tape format.

FIG. 24 is a diagram showing a subcode of user data in a tape format.

FIG. 25 is a diagram showing subcodes of tape marks in a tape format.

FIG. 26 is a diagram showing a subcode of EOD of a tape format.

FIG. 27 is a diagram showing subcodes of a dummy track of a tape format.

FIG. 28 is a diagram showing a subcode of user information in a tape format.

FIG. 29 is a diagram showing a subcode of a checksum track of a tape format.

FIG. 30 is a diagram showing a subcode of a tape format.

FIG. 31 is a diagram showing parameters of a tape format subcode.

FIG. 32 is a diagram showing parameters of a tape format subcode.

FIG. 33 is a diagram showing parameters of a tape format subcode.

FIG. 34 is a diagram showing access to a conventional user file management table.

[Explanation of symbols]

1 Main CPU 2 Dual Port RAM 3 Sub CPU 4 Bank Switch 5 Bank Memory 6 Bank Memory 7 DMAC 8 DMAC 9 Timer 10 Sub Memory 11 PIO 12 Interface 20 Recorded Area 21 VSIT 22 DIT 23 User Data Area 24 Dummy 25 Dummy 26 Dummy 26 Dummy 27 Access pointer during read / write processing 28 Access pointer during DIT reading processing 29 Access pointer for processing start by DIT after change

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Claims (4)

[Claims] 1. Data supplied from a data supply source is converted into a specific format via a data buffer, recorded on a magnetic tape, and the data recorded on the magnetic tape is reproduced to be transferred via the data buffer. In the magnetic recording / reproducing device for supplying the data to the data supply source, in the normal operation, in the pre-processing performed prior to the recording or reproducing operation, the magnetic tape produced on the basis of the above format is provided at the head portion of the magnetic tape. Management information storage means for storing management information of the magnetic tape is provided, and the storage or reproduction operation of the data is performed via the data buffer based on the management information stored in the management information storage means, and the management information is read out. Alternatively, at the time of rewriting, the management information stored in the management information storage means is stored in the data buffer. Holding, provided a random access unit for random access to the management information, a magnetic recording and reproducing apparatus is characterized in that so as to reading or rewriting of the management information. 2. The magnetic recording / reproducing apparatus according to claim 1, wherein the random access means supplies the data buffer with an instruction to change the management information from the data supply source. Magnetic recording / reproducing device. 3. The magnetic recording / reproducing apparatus according to claim 1, wherein the random access by the random access means is:
A magnetic recording / reproducing apparatus characterized in that a position for accessing the management information and a data length are designated. 4. The magnetic recording / reproducing apparatus according to claim 1, wherein only the management information of a portion rewritten by random access by the random access means is recorded on the magnetic tape. apparatus.