JPH0554537A - Digital data recording and reproducing device - Google Patents

Abstract

PURPOSE:To realize a high speed access against a random access enable magnetic tape in a digital data recording and reproducing device. CONSTITUTION:Against the sheet which is a data block consisting plural records, an advance reproduction control section 6 reads all records of of one sheet from the magnetic tape and stores them to a buffer memory 1. By this, the record access from a host computer becomes the access to the buffer memory 1 and a high speed response is realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital data recording / reproducing apparatus using a magnetic tape as a recording medium, which is used as an external storage device of a computer.

[0002]

2. Description of the Related Art In recent years, the capacity and functionality of digital data recording devices using magnetic tape have been increasing. These devices employ an error correction code in order to improve the reliability of data to be recorded / reproduced, and are devised to realize a random write / random read function of reading / writing record unit data from a host computer to an arbitrary position. It started to come. Generally, a digital data recording apparatus using a magnetic tape has an advantage that a large-capacity recording medium can be supplied at low cost as compared with a hard disk, and has a drawback that an access speed to a magnetic tape which is a recording medium is slow. In order to make up for this drawback and shorten the occupied time of the host computer, the capacity of the built-in cache memory has been increasing in these devices.

The standard proposed for realizing the compatibility of magnetic tapes is DATA /
DAT standard ("7th Draft Revised PROPOSED AMERICAN
NATIONAL STANDARD HELICAL-SCAN DIGITAL COMPUTER TA
PE CARTRIDGE 3.81mm (0.150in) DATA / DAT RECORDED FOR
MAT FOR INFORMATION INTERCHANGE "December 7, 199
There is 0).

A conventional digital data recording / reproducing apparatus will be described below. This conventional example is the DATA / D
It is assumed that the AT standard is satisfied.

FIG. 12 shows a block diagram of this conventional digital data recording / reproducing apparatus. In FIG.
The interface control unit 101 has a cache buffer management information memory 102, a control unit that controls data transfer between the host computer and the cache buffer memory 103, and the group processing unit 104 is the group memory 1
An error correction code processing unit having 05 as a work area, a magnetic recording / reproducing unit 106 for a deck for directly recording / reproducing control on a magnetic tape as a recording medium, and a rewriting control unit 107 for a recording operation received from the magnetic recording / reproducing unit 106. A control unit that controls the retry of the recording operation when it is determined that there is a problem in the recording operation based on the reliability information of the data, and the format operation control unit 1
A control unit 08 executes a formatting operation which is an initialization operation of the magnetic tape. The group attribute information storage memory 109 is a memory for storing group attribute information for managing the recording state of the magnetic tape, and the rewrite control unit 107.
Format operation control unit 108 and group processing unit 10
4 is connected to.

With respect to the digital data recording / reproducing apparatus having the above-described structure, first, the recording mode of data on the magnetic tape as the recording medium and the structure of the group which is the minimum unit for recording / reproducing on the magnetic tape will be described. Next, the format operation, data read operation, data write operation, and group rewrite operation, which are the operations of this embodiment, will be described in order.

FIG. 13 is a state diagram showing a recording form on the magnetic tape. In FIG. 13, a group consisting of 64 tracks formed obliquely and continuously in advance is recorded on the magnetic tape adjacent to each other without a gap. FIG. 14 is a structural diagram showing a logical structure of data of one group. 14
The group logically has a two-dimensional array and has a plurality of records which are fixed-capacity data blocks accessed from the host computer, system information which is management information within the group of records, and error correction code. It is composed of parity and. The data transfer direction of the record with the host computer is the direction of arrow A in FIG. 14, the error correction code having the record and system information as the information word also has arrow A as the encoding direction, and the code parity is shown in FIG.
Is stored in the area indicated by B. On the other hand, the recording / reproducing direction to the track of the two-dimensional structure of the group is an arrow C in FIG. 14, and by interleaving the direction of the error correction code and the recording direction to the magnetic tape at right angles, one code sequence is shown in FIG. As shown in D on the magnetic tape at 13, the influence of a data error caused by damage to the magnetic tape can be minimized. Further, the group memory 105 is capable of storing one group having the structure shown in FIG.

Next, as a conventional operation, a format operation will be described below. The format operation is an operation of forming a group on the magnetic tape in advance before writing / reading data from the host computer, and corresponds to the format operation of the disk device.

The host computer issues a format operation instruction command to the digital data recording / reproducing apparatus. When the interface control unit 101 receives the format operation instruction command, it instructs the format operation control unit 108 to start the format operation. First, the format operation control unit 108 obtains the number of groups that must form a format from the requested capacity, creates system information of the first group based on the DATA / DAT standard, and transfers it to the group processing unit 104. The group processing unit 104 transfers the system information to the area for storing system information shown in FIG. 14 of the group memory 105, executes the error correction code encoding process in the direction of arrow A in FIG. Complete the shape of the group. When the group is completed, the group processing unit 104 issues an operation instruction to the magnetic recording / reproducing unit 106 and causes the magnetic recording / reproducing unit 10 to operate from the group memory 105.
Data is transferred to 6 in the row direction of the two-dimensional array of groups, that is, in the direction of the arrow C in FIG. The magnetic recording / reproducing unit 106 records the transferred data on the magnetic tape, which is a recording medium, without any gap, so that the group buffer 1
A group having the data on 05 is formed on the magnetic tape. The format operation control unit 108 sequentially creates the system data in order of the group number from the first group and transfers the system data to the group processing unit 104. The group processing unit 104 confirms the timing of the transfer of the recording data to the magnetic recording / reproducing unit 106 while checking the group. The system data is sequentially transferred to the memory 105, encoded, and sent to the magnetic recording / reproducing unit 106. As a result, groups having consecutive group numbers are continuously formed on the magnetic tape without a gap.

FIG. 15 is a state diagram showing a part of the magnetic tape formatted by the formatting operation. In FIG. 15, five consecutive data groups and two consecutive spare groups are alternately formed on the magnetic tape. The data group has the data structure of the group shown in FIG. 14, and the record area is a group in which records directly accessed by the host computer are recorded. The spare group has the same data structure as the data group and is used by the data group. It is a reserve group used as a substitute when it becomes impossible.

Further, the format operation control unit 108 creates group attribute information of the group formed by the format operation and registers it in the group attribute information storage memory 109. FIG. 16 shows the structure of group attribute information, and FIG. 17 shows the definition of the attribute code. In FIG. 16, the attribute information of one group is composed of an attribute code of 1 byte and a substitute group number of 0 or 2 bytes. In the group attribute information storage memory 109, from the attribute information of the group of group number 0 in order of group number. Group information is stored, and a termination code is stored at the end thereof. The attribute code is shown in FIG.
Then, the type of the group such as whether it is the data group or the spare group, the usage status, and the error occurrence status are coded. At the end of the formatting operation, since it is a data group or a backup group, the substitute group number is not registered and is 0 byte, and the attribute code is 0x00 (in the following, hexadecimal display is indicated by 0x) or 0x04 continuously. It will be remembered.

Next, as a conventional operation, a data read operation will be described below. It is assumed that the following operation is for a formatted magnetic tape.

The host computer issues a data read operation instruction command to the digital data recording / reproducing apparatus using the record as a designated unit of a read position and a read capacity. First, the interface control unit 10
1 receives the data read operation instruction command,
Inspect the cache buffer management information memory 102,
The designated record is the cache buffer memory 103.
If it is stored, the record is transferred to the host computer and the command of the data read operation instruction is ended. If it is not stored, the command is transmitted to the group processing unit 104. The group processing unit 104 obtains the group number of the corresponding group including the record designated by the command by checking the group attribute information storage memory 109, and if the group stored in the group memory 105 matches the corresponding group, the record is searched. Interface control unit 10
Transfer to 1. The group memory 105 temporarily stores data for one group having the structure shown in FIG. The interface control unit 101 examines the cache buffer management information memory 102 and checks the cache buffer memory 1
Group processing unit 10 instead of the free area 03 or the record accessed most recently by the host computer.
The record transferred from No. 4 is stored in the cache buffer memory 103, the information in the cache buffer management information memory 102 is updated, the record is transferred to the host computer, and the command of the data read operation instruction is ended.

On the other hand, when the group stored in the group memory 105 does not match the corresponding group, the group processing unit 104 executes the buffer flushing operation and the subsequent reproducing operation.

First, in the buffer sweep operation, the group processing unit 104 completes the system information shown in FIG. 14 for the group stored in the group memory 105, executes the error correction code encoding process, and then the group memory 105.
Complete the shape of the group above. Group processing unit 10
When the group 4 is completed, an operation instruction is issued to the magnetic recording / reproducing unit 106 and data is transferred from the group memory 105 to the magnetic recording / reproducing unit 106. The magnetic recording / reproducing unit 106 overwrites the transferred data on the designated group recording area on the magnetic tape, which is a recording medium, to overwrite the data on the group buffer 105 to the group on the magnetic tape and record the data. Becomes After the group in the group memory 105 is saved on the magnetic tape by the buffer sweep operation, the group processing unit 104 starts the reproducing operation.

In the reproducing operation, the group processing unit 104 instructs the magnetic recording / reproducing unit 106 to reproduce the corresponding group including the record designated to be read from the host computer, and the magnetic recording / reproducing unit 106 magnetically reproduces the instructed group. The tape is searched, the reproducing operation is started, and the reproduced data is transferred to the group data processing unit 104. The group data processing unit 104 is the group memory 10 shown in FIG.
The transferred reproduction data is stored on the logical two-dimensional array 5 in the order of arrow C. When the reproduction of the specified group is completed and the two-dimensional array of FIG. 14 is completed on the group memory 105, the group processing unit 104 completes the data error occurring during the reproduction operation by the error correction code applied in the direction of arrow A. The error is corrected by the decoding process of (1) and the reproducing operation is completed. When the reproducing operation is completed, the group processing unit 104 is set in FIG.
The position of the record designated by the host computer on the two-dimensional array of the group is calculated by referring to the system information of the reproduced group shown in FIG. 4, and the record is transferred to the interface control unit 101 in the order indicated by the arrow A. The interface control unit 101 checks the cache buffer management information memory 102, and checks the cache buffer memory 103
Area of the cache buffer memory 10 or the record transferred from the group processing unit 104 in place of the record accessed by the host computer most recently.
3, the information in the cache buffer management information memory 102 is updated, the record is transferred to the host computer, and the data read operation instruction command is ended.

The data write operation of the conventional digital data recording / reproducing apparatus will be described below.

The host computer issues a data write operation instruction command to the digital data recording / reproducing apparatus with the record as a designated unit of the write position and the write capacity. First, when the interface control unit 101 receives a data write operation instruction command, it checks the cache buffer management information memory 102 to check whether the specified record is stored in the cache buffer memory 103, and stores it. In the case, the record is transferred from the host computer to the address of the record in the cache buffer memory 103, and when it is not recorded, the record is transferred from the host computer in place of the free area in the cache buffer memory 103 or the record accessed by the host computer most recently. The information in the management information memory 102 is updated and the command is transmitted to the group processing unit 104. Group processing unit 1
Reference numeral 04 identifies the group number of the corresponding group including the record specified by the command by checking the group attribute information storage memory 109, and if the group stored in the group memory 105 matches the corresponding group, the interface control of the record is performed. The data is transferred from the cache buffer memory 103 to the corresponding address in the group memory 105 via the unit 101, and the processing of the command of the data write operation instruction is completed.

On the other hand, when the group stored in the group memory 105 does not match the corresponding group, the group processing unit 104 executes the buffer sweeping operation and the subsequent reproducing operation, which is the same as the data reading operation described above. Same as the description. When the reproducing operation is completed, the group processing unit 104 calculates the position of the record specified by the host computer on the two-dimensional array of groups by referring to the system information of the reproduced group shown in FIG. 14, and the interface control unit at that position. Transfer the relevant record from the cache buffer memory 103 via 101,
The processing of the command of the data write operation instruction is ended.

Finally, the group rewriting operation of the conventional digital data recording / reproducing apparatus will be described below.

In the above-mentioned buffer sweep operation,
The magnetic recording / reproducing unit 106 reproduces the track immediately after recording the data on the track on the magnetic tape.
The reliability of the data of the recording operation is confirmed, and the reliability information obtained as a result is transferred to the rewrite control unit 107 as needed. The rewrite control unit 107 confirms the reliability information at the end of the buffer sweep operation, and if it determines that the reliability of the recording operation is insufficient, it regards the recording group as an error group and starts the control of the group rewriting operation.

In the group rewriting operation, first, the rewriting operation control unit 107 determines the group attribute information storage memory 1
09 to select the unused spare group that is closest to the error group. FIG. 18 is a state diagram of the magnetic tape in the group rewriting operation. In the example of FIG. 18, the group number 14 becomes the error group, and it is confirmed that the closest spare group, the group number 12, is selected as a substitute. Shows. Next, the update processing of the group attribute information is started. In the update process, the attribute code of the error group is rewritten to 0x0C which means an error group, and the group attribute information storage memory 109 shifts 2 bytes from the termination code to the attribute information of the group of the error group group number + 1 to obtain the attribute. Following the information 0x0C, the group number 2 bytes of the spare group used as a substitute for this error group is written. Next, the rewrite control unit 107 similarly writes the attribute code 0x0A, which means the used spare group, shifts the end code to the attribute information of the group with the spare group identification number +1 by 2 bytes, and writes the attribute information 0x0A. Then, 2 bytes of the group number of the group to be used by the used spare group are written. When the rewriting control unit 107 finishes the updating process of the group attribute information, the rewriting control unit 107 instructs the group processing unit 104 to add the information about the rewriting control to the error group system information stored in the group memory 105, and to add the error correction code After performing the encoding process, the magnetic recording / reproducing unit 106 is instructed to perform the recording operation again on the group on the magnetic tape in which the error has occurred. Finally, the rewriting operation control unit 1
07 instructs the group processing unit 104 to rewrite the system information of the error group stored in the group memory 105 to the content corresponding to the substitute spare group,
After the encoding process of the error correction code is executed, the magnetic recording / reproducing unit 106 is instructed to perform the recording operation by superimposing it on the spare group on the magnetic tape. If it is determined that the reliability information of the recording operation at this time is insufficient, the rewriting operation control unit 107
Regards the spare group as an error group and restarts the control of the group rewriting operation described above. If it is determined that the reliability information is sufficient, the rewrite operation control unit 107 ends the control of the rewrite operation, and the group processing unit 104 shifts to the reproduction operation following the buffer sweep operation.

As described above, in the recording operation and the reproducing operation by the conventional digital data recording / reproducing apparatus, the DAT
Random by adopting the group processing that secures high data reliability by adding error correction code and interleaving based on the A / DAT standard, and executing the recording operation by superposing on the group already formed on the magnetic tape in group units. A write / random read function is realized. Also, recording / reproducing to / from the magnetic tape is an intermittent operation for completing one group at a time, and the operation is extremely slow, but since the data transfer control with the host computer using the cache buffer memory 103 is executed, the cache buffer memory 103 is executed. The large-capacity memory increases the probability of cache hits and tries to avoid low-speed operation as much as possible. Further, in the buffer sweep operation, if the reliability of the recorded data is insufficient, the data is rewritten to the spare group, so that high data reliability is always ensured.

[0024]

However, in the above-mentioned conventional configuration, if the record instructed by the host computer to read / write does not hit the cache buffer memory 103, the buffer sweeping operation and the reproducing operation for each group are frequently performed. Will be repeated. Since the magnetic recording / reproducing unit 106 has to perform a search operation on the magnetic tape, a synchronous pull-in operation, etc., which requires a great amount of execution time for each group of recording or reproducing operations, a response will be extremely high unless a cache hit occurs. It had a problem of being late. After the power is turned on, the cache hit probability is extremely low until a sufficient number of records are stored in the cache buffer memory 103. In this case, the response becomes particularly slow.

Further, immediately after the formatting, consecutive records are stored in the same group or consecutive groups, but when the reliability of the magnetic tape itself deteriorates, the group rewriting operation frequently occurs. As a result, groups for recording consecutive records are scattered on the magnetic tape instead of consecutively. Therefore, there is a problem that the execution speed of the buffer sweeping operation and the reproducing operation for the magnetic tape is further slowed down, and the response to the host computer is further slowed down.

The capacity of the magnetic tape seen from the host computer is the total number of records in the data group.
After formatting, the operating system of the host computer (hereinafter abbreviated as OS) will manage this capacity. Therefore, a data group is added to the host for the magnetic tape whose formatting has been completed and record access from the host computer has started. There is a problem that the capacity that can be used from the computer cannot be added or increased, and therefore all the necessary capacity must be formatted on the magnetic tape before use, and extremely long format operation is essential. There is a problem that there is.

The present invention solves the above-mentioned conventional problems, and realizes a high-speed read / write response of a record instructed by a host computer in any case.
The response to the host computer does not slow down even for magnetic tapes whose reliability has deteriorated and group rewriting frequently occurs, and the capacity can be added and increased even after formatting. It is an object of the present invention to provide a digital data recording / reproducing apparatus that can omit the.

[0028]

In order to achieve this object, a digital data recording / reproducing apparatus of the present invention comprises a magnetic recording / reproducing means for recording / reproducing a group on a magnetic tape in the minimum unit, and a plurality of groups. A buffer memory for temporarily storing one sheet, and a data replacement flag memory for storing a data replacement flag indicating that at least a part of the data in the sheet stored in the buffer memory has been replaced by the data transferred from the host computer. A buffer sweep-out control means for recording a group included in a sheet stored in the buffer memory on the magnetic tape, and a pre-reproduction control means for reading out all of a plurality of groups forming one sheet from the magnetic tape to the buffer memory. , For the record stored in the buffer memory A record access control means for writing and reading a record designated by a host computer, a formatting means for forming a continuous data group and a spare group having a preset number of sheets on the magnetic tape, and initializing the contents of the buffer memory. And sheet adding means for forming a new sheet adjacent to the already formed group of magnetic tapes.

[0029]

According to the present invention, when the sheet change is requested by the host computer, the buffer sweep-out control means and the preceding reproduction control means control the recording / reproduction between the buffer memory and the magnetic tape, and the designated sheet. Since all the records are stored in the buffer memory, the specified record has already been stored in the buffer memory when the host computer requests access to the records, and a cache hit is always made to realize an extremely high-speed response.

Further, if the buffer sweep-out control means reduces the data reliability in the buffer sweep-out operation and an error occurs, all the groups on the sheet at that time are rewritten to the spare groups to be substituted, so that the group is frequently rewritten. Even if the status is changed, the recording order of the constituent groups in the sheet is immovable, and the response time to the sheet change request from the host computer is delayed without increasing the processing time of the buffer sweep operation and the pre-reproduction operation for the magnetic tape. I won't.

Further, the OS of the host computer manages the data capacity in one sheet, which is fixed, but since the total number of sheets is outside the management of the OS, the sheet adding means is still on the magnetic tape even after formatting. The capacity can be added or increased on a sheet-by-sheet basis, making it possible to omit the formatting operation that requires a long time.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. This embodiment satisfies the DATA / DAT standard as in the above-mentioned conventional example.

FIG. 1 shows a block diagram of a digital data recording / reproducing apparatus in an embodiment of the present invention.

In FIG. 1, a buffer memory 1 is a memory device that can be virtually divided into a plurality of two-dimensional pages for access, and an interface controller 2 is connected to the buffer memory 1 and an external device. A data transfer control unit, which is connected to a certain host computer, and a code processing unit 3 are connected to the buffer memory 1, and a code for executing an error correction code encoding process and an error correction process on the data stored in the buffer memory 1. It is a processing unit. The magnetic recording / reproducing unit 4 uses a magnetic tape as a recording medium, and a deck for directly magnetically recording / reproducing digital data. The buffer sweep-out control unit 5 and the preceding reproduction control unit 6 are both connected to the buffer memory 1, and the buffer sweep-out control unit 5 performs magnetic recording. The pre-reproduction control unit 6 is a control unit for outputting the recording data to the control unit 4 and receiving the reliability information in the magnetic recording operation from the magnetic recording / reproducing unit 4, and inputting the reproduction data from the magnetic recording / reproducing unit 4. .. The format operation control unit 7 and the sheet addition control unit 8 are both connected to the buffer memory 1 and both output recording data to the magnetic recording / reproducing unit 4, and the format operation control unit 7 performs the format operation which is the initialization operation of the magnetic tape. The sheet addition control unit 8 is a control unit that controls and forms a new group at the end of the formatted area of the magnetic tape. The record access control unit 9 is a control unit that controls writing of data from the host computer to the buffer memory 1 and reading of data from the host computer, and the sheet initializing unit 10 initializes the group data stored in the buffer memory 1. It is a processing unit that does. The data replacement flag memory 11 is a memory for storing the data replacement flag, which is the same number of management information as the number of pages of the buffer memory 1, and is connected to the buffer flush control unit 5 and the record access control unit 9, respectively. The group attribute information storage memory 12 is a memory that stores group attribute information that manages the recording state of the magnetic tape, and includes a buffer sweep control unit 5, a preceding playback control unit 6, a format operation control unit 7, and a sheet addition control. It is connected to the unit 8 and the record access control unit 9.

With respect to the digital data recording / reproducing apparatus having the above-mentioned structure, the data storage mode on the buffer memory 1 will be described first, and then the format operation, sheet selection operation, and rewrite operation, which are the operations of this embodiment. The operation, the record access operation, the sheet initialization operation, and the sheet addition operation will be sequentially described.

FIG. 2 is a memory map showing the data storage format of the buffer memory 1. The buffer memory 1 is shown in FIG.
14 is divided into pages, each page having the same structure as the virtual two-dimensional array of data groups shown in FIG. 14, and one group is temporarily stored in one page. In FIG. 2, the data replacement flag memory 11 has a one-to-one correspondence with each page and stores a data replacement flag indicating that the data of the data group temporarily stored in each page has been replaced by the data transferred from the host computer. Memory. In this embodiment, the total number of pages is 0
There are 6 pages from page 5 to page 5.

FIG. 3 is a structural view showing the structure of the seat.
A sheet is a block of a plurality of fixed-length records, and is composed of total records managed by the OS of the host computer at one time for this embodiment. Further, one sheet is divided into a plurality of continuous groups and stored in each page of the buffer memory 1 or recorded on a magnetic tape.
In this embodiment, it is assumed that one record is 512 bytes and one sheet is composed of 1440 records as shown in FIG. Further, since one group has 256 records, one sheet can be divided into six groups starting with the group number M, and the group number M to the group number M +
Up to 4, 256 records are allocated to each group, and 160 records are allocated to the group with the group number M + 5. Therefore, the group number M + 5 includes 96 records in a form not belonging to the sheet. Further, since the buffer memory 1 has 6 pages, it is possible to store all the records included in one sheet.

Next, the format operation of this embodiment will be described. FIG. 4 is a flowchart showing the processing of the interface control unit 2. In FIG. 4, the interface control unit 2 analyzes the command given from the host computer and requests the control unit according to each operation to perform processing. When a command requesting a format operation is given from the host computer, the interface control section 2 sends the command to the format operation control section 7 in step 601 to request control. FIG. 5 is a flowchart showing the processing of the format operation control unit 7. The format operation control unit 7 analyzes the command in step 701 of FIG. 5, calculates the number of groups to be formed on the magnetic tape from the required capacity of the format, and executes step 7
At 02, all pages in the buffer memory 1 are inspected and free pages available for formatting are selected. The 0th page is selected because all pages are available at the start of the format operation. The format operation control unit 7 creates the data of the first group according to a preset method in step 703, and stores it in the record storage area of the 0th page of the buffer memory 1 shown in FIG.
In addition, the system information is created based on the DATA / DAT standard and stored in the system information storage area of the 0th page. Next, in step 704, the code processing unit 3 is instructed to start the encoding process of the 0th page, and in step 705 the magnetic recording / reproducing unit 4 is instructed to perform the recording operation of the first group on the magnetic tape. When it is detected in step 706 that the data of all the groups to be formatted have not been created, the processes of steps 702 to 706 are repeated to sequentially use the pages of the buffer memory 1 cyclically to group the data. Are formed and recorded continuously on the magnetic tape in the magnetic recording / reproducing section 4. Step 7
If it is determined that the data of all the groups have been created in 06, and the recording operation of the magnetic recording / reproducing unit 4 has also been completed in step 707, the group attribute information of all the groups formed on the magnetic tape in the format operation in step 708. Is created and registered in the group attribute information storage memory 12, and the formatting operation is completed.

FIG. 6 is a state diagram showing a part of the magnetic tape formatted by the formatting operation. Figure 6
Group numbers 0 to 5 are DATA / DA.
In the management information recording area defined by the T standard, the records accessed from the host computer are recorded in the group number 6 and thereafter. The format operation control unit 7 sets the minimum number N of groups for storing one sheet of data and preset integer values Md and Ms to
A continuous N * Md group for recording Md sheets and a continuous N * Ms spare group are alternately formed on the magnetic tape. In this embodiment, N = 6 and Md =
2, Ms = 1, and two data sheets and one spare sheet are repeatedly formed from the 0th data sheet having the group number 6 as the head. Here, the data sheet is a sheet formed by the data group, and the preliminary sheet is a sheet formed by the preliminary group.

Next, the sheet selection operation of this embodiment will be described. In FIG. 4, the interface control unit 2 analyzes the command given from the host computer, and when it is a command for instructing the sheet selection, the sheet selection process is started, and first, in step 602, the buffer flushing control unit 5 is instructed. Requests buffer flush operation.

FIG. 7 is a flowchart showing the buffer sweep-out operation of the buffer sweep-out control section 5. The buffer flushing control unit 5 first checks all the data replacement flag memories 11 in step 1101 of FIG. 7 and if all the data replacement flags are reset, that is, all the groups temporarily stored in the buffer memory 1 are If the data has not been replaced, the buffer sweep operation is immediately ended. If the data has been replaced in any of the groups, the process proceeds to step 1102 to obtain the processing range of the buffer sweep operation. In this embodiment, the processing range condition is a range in which the group having the smallest group number of the data-replaced groups is the starting point, the group numbers are continuous, and the group in which the data is replaced is the end point. Now, assuming that the buffer memory 1 is in the state of storing the first data sheet shown in FIG. 2 and the group numbers 12, 14, and 16 are in the data-replaced state, the buffer sweep-out control unit 5 executes step 1102. Group number 1 in processing
The processing range is 5 groups from 2 to group number 16. When the buffer sweep-out control unit 5 obtains the processing range, it instructs the code processing unit 3 in step 1103 to execute the error correction code encoding process for each page in the processing range, and in step 1104, the magnetic recording / reproducing unit 4 processes. A recording operation is instructed for a range, that is, five groups starting with the group number 12 on the magnetic tape, and the corresponding page of the buffer memory 1, that is, the 0th page to the 4th page.
The page data is transferred to the magnetic recording / reproducing unit 4. The magnetic recording / reproducing unit 4 executes the magnetic recording operation by overwriting the transferred data on the recording area of the designated group number on the magnetic tape as the recording medium. When the recording operation of the magnetic recording / reproducing unit 4 is completed, the buffer sweep-out control unit 4
Resets the data replacement flag in the processing range in step 1105, and in step 1106 checks the reliability of the data in the recording operation of the magnetic recording / reproducing unit 4 on the magnetic tape,
If it is determined that the reliability is sufficient, the buffer sweep operation is immediately completed, and if it is determined that the reliability is insufficient, the rewrite operation is executed in step 1107 and then the buffer sweep operation is ended. The rewrite operation will be described later.

When the buffer sweeping operation is completed, the interface controller 2 searches the group attribute information storage memory 12 in step 603 of FIG. 4 to find the data group corresponding to the data sheet of the number designated by the host computer. If it is recorded, the preceding reproduction control unit 6 is requested to perform the preceding reproduction operation of the corresponding data sheet.

FIG. 8 is a flow chart showing the processing procedure of the pre-reproduction control section 6. First, in step 1201, the pre-reproduction control unit 6 obtains the start group number of the reproduction operation, the start page number of the buffer memory 1 to be used, and the reproduction amount.
Now, if it is requested to pre-reproduce the 0th data sheet, the group numbers 6 to 6 are reproduced, and the 0th to 6th pages of the buffer memory 1 are stored.
When the operation range is obtained, in step 1202, the magnetic reproducing operation with the group number 6 as the head is performed.
Instruct. The magnetic recording / reproducing unit 4 searches the instructed head group on the magnetic tape, starts the reproducing operation, and sequentially transfers the reproduced data to the preceding reproducing control unit 6. The pre-reproduction control unit 6 sequentially stores the transferred reproduction data from the 0th page to the 5th page of the buffer memory 1 in the logical two-dimensional array order shown in FIG. When the reproduction data transfer to all pages of the buffer memory 1 is completed, the preceding reproduction control unit 6 instructs the magnetic recording / reproduction unit 4 to end the reproduction operation from the magnetic tape, and in step 1203, the code processing unit 3
The error correction is executed by the decoding process of the error correction code applied in the direction of arrow A in FIG. The code processing unit 3 executes error correction for all the groups of the buffer memory 1, but if an abnormality such as uncorrectable or erroneous correction detection is found in any of the groups, an abnormality is found in the preceding reproduction control unit 6. Report what you have done. The pre-reproduction control unit 6 performs step 12
When it is determined that there is an abnormality in 04, the process returns to step 1201, the processes up to step 1203 are executed, and the preceding reproduction operation is retried with the abnormality occurrence group as the head group. If it is determined in step 1204 that there is no abnormality, the pre-reproduction operation ends.

The interface control unit 2 completes the sheet selection process upon completion of the preceding reproduction operation in step 604 of FIG. As a result, after the sheets already stored in the buffer memory 1 are saved on the magnetic tape, each group of newly designated sheets is stored in each page of the buffer memory 1 in the order of group numbers without any error. Will be.

Next, the rewrite operation in the above buffer sweep operation will be described. If the buffer sweep-out control unit 5 determines that the reliability of data in the recording operation of the magnetic recording / reproducing unit 4 on the magnetic tape is insufficient,
In step 1107 of FIG. 7, the rewrite operation is executed. Figure 9
4 is a flowchart showing a rewrite operation process of the buffer sweep-out control unit 5. The buffer flushing control unit 7 checks the group attribute information in step 1301 of FIG.
Select an unused spare sheet that is closest to the sheet in which the unreliable error group occurred. An unused spare sheet is a sheet made up of a spare group that is not used as a substitute for any group, and the selected spare sheet is used as a substitute for the sheet in which an error has occurred. Assuming that an error occurs when the first data sheet stored in the buffer memory 1 is swept to the magnetic tape as an example, the 0th spare sheet closest to the first data sheet is selected as a substitute sheet in the example of FIG. 12
The spare group with the group number 18 is assigned as a substitute for the group No. 18, the spare group with the group number 19 as the substitute for the group number 13, and the spare group with the group number 23 as a substitute for the group number 17 are similarly assigned. Step 13
02, when there is no unused spare sheet, the buffer sweep-out control unit 5 executes DATA in step 1303.
As a protection process based on the / DAT standard, a necessary number of spare groups are formed at the end of the groups already formed on the magnetic tape by the formatting operation and registered in the group attribute information storage memory 12, and then step 1301
Return to and select the spare sheet again. When the allocation of the spare group is completed, the buffer scavenging control unit 5 executes a modification in step 1304 to write the substitution relation information and the like into the system information of all the groups temporarily stored in the buffer memory 1 based on the DATA / DAT standard, Next, in step 1305, the group attribute information of the error group and the spare group used in its place is corrected based on the DATA / DAT standard. At this time, not only the group in which the error actually occurred is processed, but all the groups included in the sheet are processed as the error group, and the spare group which substitutes all the groups is processed. When the correction of the group attribute information is completed, the buffer flushing control unit 5 causes the code processing unit 3 to execute the encoding process on all the pages of the buffer memory 1 in step 1306, and in step 1307 all the groups of the error occurrence sheet. On the other hand, the magnetic recording / reproducing unit 4 is caused to execute the recording operation on the magnetic tape. When the recording operation is completed, the buffer sweep-out control unit 5 sets D in step 1308.
Correction is performed to rewrite the system information of all groups temporarily stored in the buffer memory 1 based on the ATA / DAT standard into the system information of the substitute spare group, and at the same time, in steps 1309 and 1310, error correction code encoding processing is performed. Then, the magnetic recording / reproducing unit 4 is caused to execute the recording operation on the magnetic tape for all the spare groups of the spare sheet. As described above, the data of all the groups of the sheet in which the error has occurred is rewritten to the spare group on the magnetic tape.

Finally, in step 1311, the buffer sweep-out control section 5 inspects the reliability information of the recording operation output from the magnetic recording / reproducing section 4 during the recording operation on the magnetic tape of the spare group, and records the data recorded on the magnetic tape. If the reliability of the above is insufficient, all groups included in the spare sheet are set as new error groups in step 1301.
Then, the rewrite processing is started, but when the reliability is sufficient, the rewrite processing is completed.

Next, the record access operation of this embodiment will be described. In FIG. 4, the interface control unit 2 analyzes a command given from the host computer, and when it is a command for instructing a record access operation for writing or reading data to or from a record, in step 605 the record access control unit 9 Request a record access operation.

FIG. 10 is a flow chart showing the processing of the record access control unit 9. In FIG. 10, when the record access control unit 9 receives a command, step 1401
Then, the page number on the buffer memory 1 of the group including the target record instructed by the host computer is calculated. At this time, the position of the record designated by the host computer is a relative position designation based on the first record in the sheet stored in the buffer memory 1. Next, the process proceeds to step 1402, the address of the target record on the buffer 1 is calculated by referring to the system information shown in FIG. 14 of the group stored in the corresponding page, and the interface controller 2 is instructed at step 1403. , The target record data is transferred from the address to the host computer if the record is read, and the target record data is transferred from the host computer to the address if the record is written. Further, in the case of a record write operation, the data replacement flag of the corresponding page of the data replacement flag memory 11 is set in step 1404. When the processing of the first relevant page is completed, the record access control unit 9 determines in step 1405 whether or not all the records requested to be transferred by the command from the host computer have been transferred to the host computer,
If there are untransferred records remaining, step 140
Returning to 1, the transfer processing of the untransferred record is continued, but if the transfer of all records is completed, the processing of the record access command is ended and the next command is waited.

Next, the sheet initialization operation of this embodiment will be described. In FIG. 4, the interface control unit 2 analyzes the command given from the host computer, and when it is the command instructing the initialization operation of the sheet currently stored in the buffer memory 1, step 606
Then, the sheet initialization unit 10 is requested to perform the sheet initialization operation.
The sheet initialization control unit 10 creates the data of the records of all the groups stored in the buffer memory 1 according to a preset method, stores the data in the record storage areas shown in FIG. 14 of all the pages of the buffer memory 1, and The data replacement flags of all pages of the data replacement flag memory 11 are set, and the sheet initialization operation is completed.

Finally, the seat addition operation of this embodiment will be described. In FIG. 4, the interface control unit 2 analyzes the command given from the host computer, and when it is a command for instructing a sheet addition operation for adding one new sheet to the magnetic tape, once starts the sheet selection processing. Then, in step 602, after sweeping out the sheet stored in the buffer memory 1 onto the magnetic tape, the sheet to be selected in the determination in step 603 does not exist on the magnetic tape, so the process proceeds to step 607. A sheet addition operation is requested of the sheet addition control unit 8.

FIG. 11 is a flow chart showing the processing of the seat addition operation control unit 8. In FIG. 11, the sheet addition control unit 8 first checks the group attribute information storage memory 12 in step 1501 to check whether the last N * Md groups formed on the magnetic tape include a spare group. When the spare group is included, it is possible to form the data sheet after the data group already formed on the magnetic tape. Therefore, the process proceeds to step 1502, and 1 is added to the final group number of the data group already formed. In step 1503, data of groups of all pages of the buffer memory 1 is created and stored in accordance with a preset method as the number of groups forming an integer value N at the head group number of the data group that newly forms an item, and System information is created and stored based on the DATA / DAT standard in accordance with the head group number and the number of groups, and the system information is encoded, and the magnetic recording / reproducing unit 4 is adjacent to the last group of the magnetic tape, which is N groups. Let it form. Further, in step 1504, the group attribute information of the newly formed N group is additionally registered in the group attribute information storage memory 12, and the sheet adding operation is completed.

On the other hand, when the final N * Md groups do not include a spare group, Ms spare sheets follow the already formed data group of the magnetic tape in order to satisfy the DATA / DAT standard. Since it is necessary to form N * Ms spare groups, step 15
In 05, 1 is added to the last group number of the data group already formed to the start group number of the newly formed spare group, and N * Ms is added to the start group number of the newly formed data group. , The number of spare groups forming the integer value N * Ms is set as the number of data groups forming the integer value N, the process proceeds to step 1506, and all pages of the buffer memory 1 are processed in the same manner as in step 702 to step 707 of the formatting operation of FIG. To make the magnetic recording / reproducing unit 4 form N * Ms spare groups and N data groups adjacent to the already generated final group of the magnetic tape. Further step 1
The group attribute information storage memory 12 stores the group attribute information of the spare group and the data group newly formed in 507.
Additional registration is performed to finish the sheet adding operation.

At the end of the sheet adding operation, the buffer memory 1 stores the last data sheet regardless of whether the spare group is added or not. Therefore, one new data sheet is added to the magnetic tape. Further, that sheet has been selected on the buffer memory 1.

As described above, according to the present embodiment, the data can be accessed from the host computer by the data sheet number and the relative record number in the data sheet, and the buffer memory capable of storing all the data of one sheet. 1
By providing the above, when the record is accessed from the host computer, the record is already stored in the buffer memory 1 without fail, and it is not necessary to magnetically reproduce it from the magnetic tape, so that an extremely fast response is always realized. According to the present embodiment, the data structure of one sheet has the same structure as a double-sided double-density double-track floppy disk (hereinafter, abbreviated as 2DD) of 1-track 9-sector format, so that the host computer virtually 1 sheet. Can be treated as one 2DD floppy disk, one magnetic tape is regarded as a magazine containing a plurality of 2DD floppy disks, and the digital data recording / reproducing apparatus of this embodiment has an autochanger function for selecting an arbitrary floppy disk from the magazine 2DD floppy drive device. Host computer OS is 2D
Data management is performed within the range of the D floppy, that is, within the range of one sheet, and replacement of the 2DD floppy by a person or an autochanger corresponds to a sheet selecting operation. In other words, the record access operation and sheet selection operation are
Complete compatibility with the DD floppy drive can be achieved, so large capacity magnetic tape can be used at high speed without providing any special function in the OS of the host computer, which is extremely versatile and practical. Is.

In the sheet selection operation, the buffer sweep-out control section 5 executes the buffer sweep-out operation with reference to the data replacement flag. Therefore, the data rewritten from the host computer in the buffer memory 1 is recorded on the magnetic tape. If there is no danger of losing without doing so, and if the reliability of the recorded data is insufficient in the buffer sweep operation, the rewrite processing of step 1107 is executed, so the reliability of the data on the magnetic tape can always be kept high. Further, since the pre-reproduction control unit 6 retries when the data pre-reproduced from the magnetic tape in Step 1204 includes an abnormality, the pre-reproduction control unit 6 does not transfer erroneous data to the host computer and realizes high reliability of the transferred data. can do. On the other hand, regarding the group arrangement, the format operation control unit 7 previously forms a data group and a spare group for each sheet by the format operation as shown in FIG. 6, and an error occurs in the rewrite operation of the buffer sweep-out control unit 5. Since the sheet is rewritten as a spare sheet for each sheet, the group arrangement in the sheet is never disturbed by the rewrite operation. Therefore, even if the deterioration of the magnetic tape progresses and the rewrite operation frequently occurs, the sheet selection operation can be always completed by the magnetic recording / reproducing operation for the continuous group on the magnetic tape. Therefore, the sheet selection operation can be always completed in the shortest time. Is.

Further, by providing the sheet initializing section 10, the data stored in the buffer memory 1 can be initialized by the sheet selecting operation. From the viewpoint of the OS of the host computer, this corresponds to the operation of formatting one 2DD floppy mounted in the 2DD floppy drive, and realizes extremely high compatibility with the 2DD floppy drive.

Finally, by providing the sheet adding means 8, a new sheet can be added to the magnetic tape at any time. This is an operation outside the jurisdiction of the OS, since it is equivalent to the addition of a 2DD floppy disk mounted in the magazine when viewed from the OS of the host computer, and the compatibility and versatility are impaired by adding a seat. Never. On the contrary, since it is possible to increase the usable data capacity of the magnetic tape by adding sheets at any time, the format operation control unit 7 can reduce or omit the format operation capacity. This makes it possible to omit a long-time formatting operation when starting to use a large capacity magnetic tape.

As described above, the present embodiment has the high practicality of solving the problems of the conventional digital data recording / reproducing apparatus using the magnetic tape and realizing the compatibility with the conventional floppy drive apparatus. Since it realizes an access speed extremely higher than that of the device, it is suitable for use as a secondary storage device of a host computer while using a magnetic tape as a recording medium.

In the present embodiment, the interface controller 2, the buffer sweep controller 5, the preceding playback controller 6, the format operation controller 7, the sheet addition controller 8, the record access controller 9, and the sheet initialization. Although the units 10 are independent control units, they may be replaced by one microprocessor and each process may be realized by software. Further, in the present embodiment, the data structure of the sheet is the same as that of the 2DD floppy, but the sheet structure is the same as the data structure of other exchangeable media, and the buffer memory 1 can store all the new data structures. It may be configured to have a large capacity. Further, the interface control unit 2 includes an operation switch,
The sheet number may be manually input from the outside.

[0060]

As described above, according to the present invention, when the host computer requests the sheet change, the buffer sweep-out control means and the preceding reproduction control means control the recording / reproduction between the buffer memory and the magnetic tape, and the designated operation is performed. Since all the records of the sheet are stored in the buffer memory, the specified record has already been stored in the buffer memory when the host computer requests access to the records, and it is necessary to magnetically reproduce from the magnetic tape by the cache hit. It does not occur and realizes extremely high-speed response.

Further, when the buffer sweep-out control means reduces the data reliability in the buffer sweep-out operation and an error occurs, all the groups of the sheet at that time are rewritten to the substitute spare group as a target, so that the group is frequently rewritten. The recording order of the constituent groups in the sheet is immovable even when the status is set to ON, and the buffer sweep operation and the preceding playback operation for the magnetic tape can always be completed by the magnetic recording / playback operation for the continuous group on the magnetic tape. After the processing is completed, high-speed response can be realized even in response to a sheet change request from the host computer.

Further, the OS of the host computer manages the data capacity in one sheet, which is fixed. However, the total number of sheets is outside the management of the OS, so the sheet adding means can arbitrarily set the magnetic field even after formatting. The capacity can be added or increased in units of sheets on the tape, and the formatting operation that requires a long time can be omitted or shortened.

Furthermore, the digital data recording / reproducing apparatus of the present invention has extremely high versatility and practicability by matching the data structure of the sheet with the data structure of the media of the conventional computer exchangeable media storage device. Can be realized and its effect is enormous.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a digital data recording / reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a memory map of a buffer memory 1 in the same embodiment.

FIG. 3 is a schematic view showing a structure of a seat in the same embodiment.

FIG. 4 is a flowchart showing a processing operation of an interface control unit 2 in the embodiment.

FIG. 5 is a flowchart showing a processing operation of a format operation control unit 7 in the embodiment.

FIG. 6 is a state diagram of a magnetic tape after being formatted in the embodiment.

FIG. 7 is a flowchart showing the operation of the buffer sweep-out processing of the buffer sweep-out control unit 5 in the embodiment.

FIG. 8 is a flowchart showing a pre-reproduction operation of a pre-reproduction control unit 6 in the same embodiment.

FIG. 9 is a flowchart showing the rewrite processing operation of the buffer sweep-out control unit 5 in the embodiment.

FIG. 10 is a record access control unit 9 in the embodiment.
Flowchart showing the processing operation of

FIG. 11 is a flowchart showing the processing operation of the seat addition control unit 8 in the embodiment.

FIG. 12 is a block diagram showing a configuration of a digital data recording / reproducing apparatus in a conventional example.

FIG. 13 is a schematic view showing a recording state of a magnetic tape in the conventional example.

FIG. 14 is a schematic diagram showing a logical structure of a group in the conventional example.

FIG. 15 is a schematic diagram showing a state of a magnetic tape after formatting in the conventional example.

FIG. 16 is a schematic diagram showing a structure of group attribute information in the conventional example.

FIG. 17 is a definition diagram of an attribute code of group attribute information in the conventional example.

FIG. 18 is a schematic diagram showing a state of a magnetic tape during a group rewriting operation in a conventional example.

[Explanation of symbols]

 1 Buffer Memory 2 Interface Control Section 3 Code Processing Section 4 Magnetic Recording / Reproducing Section 5 Buffer Sweeping Control Section 6 Preceding Playback Control Section 7 Format Operation Control Section 8 Sheet Addition Operation Control Section 9 Record Access Control Section 10 Sheet Initialization Section 11 Data Replacement Flag memory 12 Group attribute information storage memory

Claims (9)

[Claims] 1. A recording / reproducing means for recording / reproducing data on / from a recording medium, and a sheet which is a block of fixed-capacity data and which is reproduced by the recording / reproducing means from the recording medium. And a buffer memory for temporarily storing all records included in the digital data recording / reproducing apparatus for accessing a record specified by the host device on a sheet specified by the host device. 2. A digital data recording / reproducing apparatus according to claim 1, further comprising operation means for manually specifying a sheet number from the outside. 3. A data replacement flag memory for storing a data replacement flag indicating that at least a part of the data of the sheet stored in the buffer memory has been replaced by the data transferred from the host device, and the designated sheet is buffered. Different from the sheet stored in the memory, and when the data replacement flag indicates that the data has been replaced, at least the replaced data is recorded in a corresponding position on the recording medium, and the data replacement flag is initialized. Buffer sweeping control means for controlling the buffer sweeping operation, and the designated sheet when the designated sheet is different from the sheet stored in the buffer memory and the data replacement flag does not indicate that the data has been replaced. Play all the records contained in the Claim and a preceding reproducing control means for controlling the preceding reproducing operation for re temporary storage 1 or claim 2
The described digital data recording / reproducing apparatus. 4. A code processing means for detecting whether or not there is an abnormality in the data reproduced from the recording medium, wherein the preceding reproduction control means reproduces from the recording medium again when it detects that the code processing means is abnormal. 4. The digital data recording / reproducing apparatus according to claim 3, wherein the protection processing is performed. 5. A record having a relative record number that matches a record number designated by a higher-level device with respect to a virtual relative record number based on a first record in a sheet stored in a buffer memory is used as the upper-level record. 4. The digital data recording / reproducing apparatus according to claim 3, further comprising a record access control means for setting the data replacement flag as a starting point of data transfer with the apparatus. 6. The recording / reproducing means is a magnetic recording / reproducing means which uses a magnetic tape as a recording medium and records / reproduces a group of fixed-capacity data as a minimum unit, and a minimum including all records included in one sheet. Number of groups N, a preset integer Md, and a preset integer Ms, and a continuous N * Md group for recording Md sheets on the magnetic recording / reproducing means, and a continuous N. 4. The digital data recording / reproducing apparatus according to claim 3, further comprising format control means for alternately forming * Ms spare groups on the magnetic tape. 7. If the buffer sweep-out control means detects that the reliability of the data recorded in the magnetic recording operation on the magnetic tape by the magnetic recording / reproducing means is insufficient, the buffer memory stores the sheets stored in the buffer memory. 7. A digital data recording / reproducing apparatus according to claim 6, further comprising a protection process for recording all records in a continuous spare group formed on a magnetic tape in advance. 8. A digital data recording / reproducing apparatus according to claim 6, further comprising a sheet initializing means for generating preset initial data of all records included in one sheet and storing the preset initial data in a buffer memory. 9. If the final contiguous N * Md groups of groups already formed on the magnetic tape do not include a contingency group, contiguous N * Ms conservative groups and their contiguous sheets are used. 7. The digital data recording / reproducing apparatus according to claim 6, further comprising sheet adding means for forming N groups to be recorded adjacent to the end of the already formed groups on the magnetic tape.