JPH0329166A - Control system for magnetic tape device and buffer memory - Google Patents

Abstract

PURPOSE:To reduce positioning frequency in the recording start position of a magnetic tape by recording all data to be recorded in a magnetic tape by an appending function in the magnetic tape and then recording the data in the magnetic tape by an update-in-place function. CONSTITUTION:A host computer 13 transfers data to be recorded in the magnetic tape to a buffer memory 12 through a bus 15. Information indicating whether the data are to be recorded by the update-in-place method or the appending method is added, and in the case of recording the data in the magnetic tape, all the data to be recorded by the appending method are recorded in the magnetic tape and then the residiual data are recorded by the update-in- place method. Thus, the positioning frequency to the recording start position can be reduced by connecting the buffer memory 12.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic tape device, and more particularly to a control method for a magnetic tape device and a buffer memory having a function of rewriting already recorded data. [Prior Art] Magnetic tape devices usually record data sequentially from the beginning of the tape. When new data is to be recorded on a magnetic tape, a so-called append method is used in which the new data is recorded following the end of previously recorded data.

Japanese Unexamined Patent Application Publication No. 63-251971 discloses a method for enabling so-called update-in-place recording in which data that has already been recorded is rewritten in a magnetic tape device. In this method, data is organized into blocks in appropriate units, and recording and playback is performed on magnetic tape using these blocks as units. On the magnetic tape, ampules of appropriate length are recorded between blocks.

An overview of data recording using the update-in-place method will be explained using Figure 10. Figure 10(a) shows the format of a magnetic tape when using the update-in-place method. 101, 102, 103
is a block in which the data described above is grouped in appropriate units. Ampules are recorded between these blocks.
An ampoule 104 is recorded between block (n-1) 101 and block (n) 102, and an ampoule 105 is recorded between block (n) 102 and block (n+1) 103. These ampoules are here assumed to have a length of L. Among these blocks, for example the block (
n) The case of rewriting 102 will be explained. 10th
As shown in Figure (b), recording is performed in a form in which ampoules 107 and 108 each having a length of 1/2 L are added before and after data 106 to be newly recorded in block (n) 102, respectively.

When this data is recorded on a magnetic tape having the format shown in FIG. 10(a), it becomes as shown in FIG. 10(Q). In this case, both the recording start position 109 and the recording end position 110 of the data to be rewritten (including the ampoule) are within the ampoule areas 104 and 105. Therefore, even if the rewriting start position is shifted forward or backward by half the length L of the ampoule 104, the rewriting may cause data to be recorded overlapping the data of the previous or next block, or the rewritten block, in this case block (n ) 102 old data will not remain. Therefore, the length L of the ampoule in the magnetic tape format is determined by taking into consideration the amount of deviation of the writing start position. In this way, even in magnetic tape devices, methods have been devised that allow data already recorded on a magnetic tape to be rewritten in units of a certain unit, in the above example, in units of blocks. In magnetic tape devices, buffer memories are used to reduce the time required to record data on magnetic tape. In a magnetic tape device, when recording data on a magnetic tape, it takes time to position the tape to the recording start position. The buffer memory is used to reduce the number of times the positioning process to the recording start position is performed. For example, when the unit of recording data on a magnetic tape is a block, instead of sequentially recording each block on the magnetic tape, the data to be recorded is stored in a buffer memory, and several blocks are recorded together on the magnetic tape. Record it in . This eliminates the need for positioning to the recording start position for each block, making it possible to reduce the time required for data recording by that much. Figure 2 shows the configuration when using buffer memory. A buffer memory 12 is provided between the magnetic tape device 11 and a host computer 13 that uses the magnetic tape device 11 as a storage device.
Establish. The magnetic tape device 11 and the buffer memory 12 are connected by a bus 14, and the buffer memory 12 and the host computer 13 are connected by a path 15. The function of the buffer memory will be briefly explained with reference to FIG. Figure 11(a) shows the format of the magnetic tape. block(
n-1) 131, block (n) 132, block (n
+1) 133 are recorded sequentially from the beginning of the tape. Buffer memory 12 is not connected and bus 1
5 allows host computer 13 and magnetic tape device! ! 1
Consider the case where 1 is directly connected. Figure 11(b)
As shown in FIG.
4, Data 13 to be recorded in block (n) 1 3 2
5. Data 13 to be recorded in block (n+1) 133
4 is transferred to the magnetic tape device 11, but for example, there is a time gap shown in 125 between data 134 to be recorded in block (n-1) 131 and data 135 to be recorded in block (n) 132. occurs. This time is necessary for the host computer 13 to prepare the data 135 to be recorded in the block (n) 132. However, when a time gap occurs in this way, the magnetic tape device 11, after recording data 134 in block (n-1) 131, temporarily stops running the tape at the position shown in block (n) 132, and records data 134 in block (n) 132. Data to be recorded 1
35 is transferred, and when the transfer of data 135 starts, positioning to the recording start position is performed, and data recording to block (n) 132 is performed.

In this way, when the host computer 13 is unable to continuously transfer data to be recorded on a magnetic tape to the magnetic tape device 11, the magnetic tape device 11 stops running the magnetic tape and transfers data to the magnetic tape device 11 each time when starting recording. It is necessary to position to the recording start position. On the other hand, the first
In Figure 1 (C), the buffer memory 12 is connected to the magnetic tape device 11.
The case where the host computer 13 is connected to the host computer 13 is shown. From host computer l3 to buffer memory 12
Even if the data transferred from the buffer memory 12 to the magnetic tape device 11 is at the same timing as shown in FIG. It can be made into something. The data transferred on bus 15 is block (
Data 134 to be recorded in block (n-1) 131, block (n
) 132, data 135, block (n+1)
There is a time gap 125 between the data 136 recorded in 133 and
, 126, the buffer memory 1
By temporarily storing it in block 2, when it is transferred to the magnetic tape device fall through the bus 14, the block (n-1)
From data 134 recorded in block 131, block (n+1
) 133 up to data 136 are continuous. As a result, the magnetic tape device I! 11, the block (n
-1) Block (n) from recording start position 121 of 131
+1) It becomes possible to record continuously up to the recording end position 124 of 133 without stopping the tape, reducing the number of times of positioning to the recording start position compared to the case where the buffer memory 12 is not connected. becomes possible. The larger the capacity of the buffer memory, the fewer times the recording start position must be positioned.

Regarding methods for reducing data recording time using buffer memory in such magnetic tape devices, see, for example, "
Latest Magnetic Recording Technology, Devices and Equipment” Edited by the Editorial Committee for Latest Magnetic Recording Technology and Devices and Equipment (Sogo Gijutsu Publishing), Chapter 3, r3
．． 1/2 inch streamer type magnetic tape device. [Problems to be Solved by the Invention] As described above, buffer memories are used in magnetic tape devices to shorten data recording time.

In a magnetic tape device using such a buffer memory, let us consider a case where data is recorded by the update-in-place method as disclosed in the above-mentioned prior art.

FIG. 12(a) shows a tape format including an area where data is recorded using the update-in-place method and an assist-date-in-place area. In this example, block (n) 141 to block (n+4) 14
After five blocks up to 2 were recorded using the update-in-place method, blocks (n+5) 143 to (n+9) 144 were recorded using the append method. In this state, consider a case where the host computer 13 instructs data recording processing in the following order. (1) Block (n+10) 1
Data is recorded in four blocks from block 45 to block (n+13) 146 using the append method. (2) Data is recorded in block (n+2) 140 using the update-in-place method. (3) Following the data recorded in (1), record four blocks from block (n+14) 147 to block (n+17) 148 using the append method. Through these processes, the data recording state on the magnetic tape becomes as shown in FIG. 12(b). When these processes are executed, data to be recorded on the magnetic tape is stored in the buffer memory in the form shown in FIG. 12(c). That is, from block (n+lO) 145 to block (n+1
3) Data 149 to 150 to be recorded up to 146, data 151 to be recorded to block (n+2) 140, and data 152 to 1 to be recorded from block (n+14) 147 to block (n+17) 148.
53 are stored in the buffer memory. Let us consider the case where the data stored in this buffer memory is recorded on a magnetic tape by the magnetic tape device 11. 12th
As shown in Figure (d), in this case, the recording start position is first positioned at position 154, and block (n+
1 (g), 145 to block (n+13) 146 are recorded. Subsequently, in order to record data in block (n+2) 140, a recording start position is determined at position 155. After recording block (n+2) 140, this time block (n+14) 147 to block (n+14) 147 are recorded.
+17) In order to record 148, the recording start position is determined at position 156. Even though the buffer is connected to the memory in this way, the number of times the magnetic tape is positioned to the recording start position is not reduced, and the data recording time cannot be shortened.

These problems occur when performing update-in-place recording on magnetic tape, that is, when re-recording already recorded data. When re-recording data recorded using these update-in-place methods and additionally recording data using the append method, each recording area is located at a separate location on the magnetic tape, so Therefore, the number of times of positioning to the recording start position increases.

As described above, conventional magnetic tape devices have a problem in that the buffer memory does not function effectively when recording data using the update-in-place method.

An object of the present invention is to provide a magnetic tape device and a buffer memory that can reduce the number of times of positioning to a recording start position by connecting a batzer memory even in a magnetic tape device that records data using an update-in-place method. The objective is to provide a control method.

[Means to solve the problem]

The above purpose is to add information indicating whether the data is recorded using the update-in-place method or the append method to the data stored in the buffer memory. When recording data on magnetic tape, this can be achieved by controlling the data to be recorded using the update-in-place method after all the data to be recorded on the magnetic tape has been recorded using the append method. It will be done. [Operation] When a magnetic tape contains an area where data is recorded using the update-in-place method and an area where data is recorded using the append method, these areas are separated from each other on the magnetic tape as described above. It will exist. Information indicating whether the data is recorded using the update-in-place method or the append method is added to each data stored in the buffer memory, and data is transferred from the storage memory to the magnetic tape. When recording data, first, by referring to this information, the data to be recorded in the append method is recorded all at once. In this case, the data recorded using the append method will be updated in between.
If you do not want to insert data to be recorded using the place method,
Data that is recorded continuously on magnetic tape. Therefore, all the data stored in the buffer memory and recorded using the append method can be recorded by starting recording and positioning the data once. Subsequently, the data to be recorded is recorded on the magnetic tape by the update-in-place method, which is not recorded but is held in the buffer memory. As a result, at least one positioning to the recording start position is required to record data on the magnetic tape for data recording using the append method, so it is possible to reduce the number of times of positioning to the recording start position, and the data can be recorded using the append method. It is possible to shorten the recording time. [Embodiment] An embodiment of a control method for a magnetic tape device and a buffer memory connected thereto according to the present invention will be described in detail with reference to the drawings. The magnetic tape device and buffer memory are connected as shown in FIG. The magnetic tape device 11 is connected via a bus 14 to a buffer memory 12, and the buffer memory 12 is connected via a bus 15 to a host computer 13 that uses the magnetic tape device 11 as a storage device. Figure 1 shows the flow of processing for recording data on magnetic tape in the configuration shown in Figure 2. First, host computer 13
transfers the data to be recorded on the magnetic tape to the buffer memory 12 via the bus 15 (step 1). The buffer memory 12 uses the append method to determine whether the transferred data is data to be recorded on a magnetic tape or updated.
Information indicating whether the data is to be recorded on a magnetic tape by an in-place method is added and stored in the buffer memory 12 (step 2). First, the magnetic tape device 11 sequentially receives data to be recorded on a magnetic tape from among the data stored in the buffer memory 12 via the bus 14 using an append method, and records the data on the magnetic tape (step 3).

At this time, the information added in step 2 is used.

After all the data to be recorded on the magnetic tape using the append method stored in the buffer memory 12 is recorded on the magnetic tape, the data is recorded on the magnetic tape using the update-in-place method stored in the buffer memory 12. Data is received via bus 14 and recorded on magnetic tape (step 4).

FIG. 3 shows an embodiment in which data to be recorded by the update-in-place method and data to be recorded by the append method are distinguished by flags in the buffer memory 12.

The process of the host computer 13 in data transfer from the host computer 13 to the buffer memory 12 is described in the third example.
Shown in Figure (a). The host computer 13 first checks whether there is free space in the buffer memory 12 (step 5).
1) If there is free space, transfer one block of data to the buffer memory 12 (step 52). These processes are repeated until all data to be recorded on the magnetic tape has been transferred (step 53).

The above processing corresponds to step 1 in FIG.

At this time, the processing in the bathopha memory l2 is shown in Fig. 3 (
Shown in b). Each time the buffer memory 12 receives one block of data (step 54), it determines whether the data is a block to be recorded using the update-in-place method (step 55). - If the block records data using the place method, a flag (update-in-place flag) indicating that the data is recorded using the update-in-place method is added (step 56), and the data is recorded using the append method. If the data is to be recorded by the append method, a flag (append flag) indicating that the data is to be recorded by the append method is added (step 57) and stored in the buffer memory 12. Similar to the host computer 13, these processes are repeated until all data to be recorded on the magnetic tape is stored in the buffer memory 12 (step 58). The above process corresponds to step 2 in FIG.

The configuration of the buffer memory at this time may be any type that can store the data, the number of the block in which the data is recorded, and the above-mentioned flag. For example, in Figure 4 (
As shown in a), there is an area 6 for storing the block number at the beginning of each data 63 stored in the buffer memory.
1 and an area 62 for storing a flag indicating whether data recording is to be performed by the update-in-place method or by the append method. In addition, as shown in FIG. 4(b), there is an area 64 for storing data to be recorded on the magnetic tape, an area 65 for storing the block number in which the data is to be recorded, and an area 65 for storing data to be recorded on the magnetic tape. It is also possible to separately provide an area 66 for storing a flag indicating whether recording is to be performed according to a method, and to manage the flags in correspondence with each other.

FIG. 5 shows a diagram from the buffer memory 12 to the magnetic tape device 11.
This shows the process of data transfer to. Although not shown, the magnetic tape device 1l records the transferred data on a magnetic tape. First, N is set to l (step 71). Here, N is a value indicating the order in which the data stored in the buffer memory 12 was transferred from the host 1 to the computer 13.

In other words, when N=1, this indicates the data of the block that the host computer 13 first transferred to the buffer memory 12, and when N=2, it indicates the data that was transferred to the buffer memory 12 next. The magnetic tape device 11 first checks the flag of the data first transferred from the host computer 13 stored in the buffer memory 12, that is, the data of N=1 (step 72). If the append flag is set, the data is transferred to the magnetic tape device 11 (step 73). Although not shown, the magnetic tape device 11 records the transferred data on a magnetic tape. Next, 1 is added to N (step 74), it is checked whether all the data stored in the buffer memory has been processed (step 75), and the above operation is repeated until all data has been processed. repeat. Buffer memory 12
After all processing of the data stored in the buffer memory is completed, the data remaining in the buffer memory and having the update-in-place flag set is transferred to the magnetic tape device 11 (step 76). The above processing is performed in the sixth
A case in which data is recorded on the magnetic tape shown in the figure will be specifically explained as an example.

In FIG. 6, block (n) 21 to block (n)
+3) The four blocks up to 22 are blocks recorded in the past using the update-in-place method. Six blocks from block (n+4) 23 to block (n+9) 24 are blocks recorded in the past using the append method.

As mentioned above, in the case of the update 1...in-place method, the ampoule parts 25, 26, 27, 28 are placed between the blocks.
, 29 are recorded. A case in which data recording processing is performed on this magnetic tape according to instructions from the host computer 13 will be explained. (1) Block (n+9) Following 24, record 5 blocks using the append method. (2) Data is recorded in block (n+2) 30 using the 7-update-in-place method. (3) Following the block recorded in (1), record 5 blocks using the append method. These processes result in data being recorded on the magnetic tape shown in FIG. 6(a) and in the form shown in FIG. 6(b). When the buffer memory 12 is used in the form shown in FIG. 4(a), data is stored in the buffer memory 12 in the form shown in FIG. 7 through these processes. First, data 201 to be recorded in block (n+lo) 31 includes its block number (n+10) 202 and an append flag in flag area 203 to indicate that data recording will not be performed using the update-in-place method. It is stored in the form set to . Similarly, block (n+1
4) Five blocks of data are stored in the buffer memory 12 up to the data to be recorded in 32. Next, data 2 to be recorded in block (n+2) 30 is stored in the buffer memory 12.
04, the block 192os and an update-in-place flag indicating that data recording is to be performed using the update-in-place method are stored in the flag area 206.
It is stored in the buffer memory 12 in the form set to .

Next, block (n+15) 33 to block (n+
19) The data to be recorded in 34 is stored in the buffer memory 12 in the same manner as the block (n+10) described above.

The data stored in these buffer memories 12
According to the process shown in the figure, the data is transferred to the magnetic tape device 11 in the following order. First, the data to be recorded from block (n+io) 31 to block (n+14) 32 is transferred as is to the magnetic tape device 11 because the append flag is set in the flag area, and
1 records those data on magnetic tape. The data stored in the buffer memory 12 following these data is the data to be recorded in block (n+2) 30, but since the update in place flag is set in the flag area. No data is transferred to the magnetic tape device all at this point, and the buffer memory 1
It is kept within 2. Continue block (n+15)3
Data to be recorded from block (n+19) 34 is stored in the buffer memory 12, but since the append flag is set in the flag area, these data are transferred to the magnetic tape device 11 as is. Since these processes are performed continuously, ten blocks of data are continuously transferred to the magnetic tape device 11 from data recorded in block (n+10) 31 to data recorded in block (n+19) 32. Magnetic tape device 1
l is block (n+10) 31 by a method not shown.
After positioning at the recording start position 36, these data are continuously recorded on the magnetic tape.

After the transfer of the data to be recorded in the block designated for data allocation using the append method and the recording on the magnetic tape are completed, the data to be recorded in the block (n+2) 30 remaining in the buffer memory 12 is The data is transferred to the magnetic tape device 11. At this time, the magnetic tape device ↓1 positions the block (n+2) 30 at the recording start position 35 and updates this data.
Block (n+2)3 of magnetic tape by place method
Record to the position where 0 is recorded.

The operation of the magnetic tape due to these processes is shown in Figure 6 (c
) is shown in the form. That is, positioning is performed at the recording start position 36 of block (n+10) 31 (37), and 1 is recorded from block (n+10) 31 to book (n+19) 34.
After recording data for block 0 (38), block (
Positioning is performed at the recording start position 35 of (n+2) 30 (3
9), recording of block (n+2) 30 is performed (40).

In this way, a flag is added to the data recorded in each block to identify blocks that record data using the in-place method and blocks that record data using the append method. in·
By controlling the recording of blocks to be recorded on the magnetic tape using the place method after all blocks for data recording using the append method have been recorded on the magnetic tape, the number of times of positioning to the recording start position on the magnetic tape can be reduced. It is possible to reduce the data recording time.

In FIG. 8, the buffer memory 12 is divided into two areas in advance and controlled, and the same effect as the above-described embodiment is obtained. The area 65 is a buffer memory used for storing data of a block in which data is recorded using the update-in-place method, and the area 66 is used as an area for storing data in a block in which data is recorded using an append method. In step 12, the processing shown in FIG. 9 is performed. This corresponds to the processing in step 2 in the first round. When the batho memory 12 receives the data transferred from the host computer 13 (step 81
), first, it is checked whether the data is to be recorded using the update-in-place method or the append method (step 82).

If the data is to be recorded in a block that records data using the update-in-place method,
The data is stored in the data area 65 for data recording using the update-in-place method shown in FIG. 8 (step 83). Further, data of blocks to which data is recorded by the append method is processed for all blocks to which the host computer 13 transfers data by the append method shown in FIG. 8 (step 85). Data transfer from the buffer memory 12 to the magnetic tape device 11 is first performed from data stored in the data area 66 where data is recorded using the append method. After all the data stored in the area 66 is transferred to the magnetic tape device 11, that is, after it is recorded on the magnetic tape, the data stored in the data area 65 is transferred to the magnetic tape device 11. Transfer to tape device 11. In the above explanation, the data in the area where data is recorded using the update-in-place method is transferred to the magnetic tape device after all the data in the data area where data is recorded using the append method has been transferred. The purpose can also be achieved by recording only the time just before the end of use of the magnetic tape loaded in the magnetic tape device.

In this case, the data stored in the buffer memory can be read out if required by the host computer. Also, when the magnetic tape is loaded into the magnetic tape device, the update information on the magnetic tape is
The data of the block recorded using the place method is read into the data area where data is recorded using the update-in-place method of the buffer memory, and the data is subsequently read between the host computer and the block where data is recorded using the update-in-place method. The data transfer can be performed between the buffer memory and the magnetic tape without actually accessing it.

Next, an embodiment will be described in which the magnetic tape device and buffer memory control method of the present invention is applied to a so-called helical scan type magnetic tape device.

The magnetic tape device of this embodiment uses DAT as a magnetic tape.
It uses the magnetic tape used in (digital audio tape recorders).

The magnetic tape device of this embodiment includes a rotating cylinder 301, read heads 311a and 31lb, write heads 312a and 312b, R/W (read/write) times lII3l3, a verify circuit 314, a servo circuit 315, and a cylinder as shown in FIG. Motor 316, capstan motor 3
17, reel motor 318, DAT signal processing circuit 319
, serve code control circuit 320, drive control circuit '3
2 1 , DAT code decoding circuit 322, memory control circuit 323, layered ECC (layered error correction code) circuit 1324, buffer memory 325, system control circuit 326, SCSI (Small Computer System Interface) 327, hardware operating circuit 32
Consists of 8. The read heads 311a, 31lb and the write heads 312a, 312b are rotary cylinders 31.
0 with azimuth angles that differ from each other by ±20 degrees.

The format of the magnetic tape 329 used in the magnetic tape device of the present invention is based on the DAT recording format 1. The magnetic tape 329 is tilted at a read angle of 6 degrees and 22 minutes with respect to the rotary cylinder 310.
As the magnetic tape 329 rotates at 200 Qrpa+, the magnetic tape 310 is wound around the read head 311a, 31lb, the write head 312a, 312.
b is to be scanned obliquely on the magnetic tape 329, and due to the recording operation of the write heads 312a and 312b,
Tracks as shown in FIG. 14 are recorded on the magnetic tape 329.

In FIG. 14, 331 is a rack 1 recorded by the write head 312a, and 322 is a track recorded by the write head 312b. In this way, gapless azimuth recording is performed by recording so that the azimuth angles of adjacent tracks are different and by overlapping a portion of the immediately preceding track. Track pitch P is 1
3.6 μm, track length L is 23.51111, recording 1
Shizu W is 2.61Ul1.

Figure 15 shows the structure of the signals recorded on each track. This track format was standardized by the DAT conference.

It is divided into areas, and various signals are recorded in each divided area.

The track is placed on the magnetic tape 329 medium 128
PGM signal area (PCM) 343 of data block,
A T 1” signal (automatic track finding signal, tracking reference signal) area (ATF-1, ATF-2) 342, 3 arranged on both sides of the
44. Further, subcode areas (SUB-1, SUB-2) 34 each consisting of 8 data blocks are arranged outside of the subcode area.
Consisting of 1,345.

In the DAT, a PCM (pulse code modulation) signal area 343 records data obtained by adding an error correction code to digital data obtained by converting an audio signal into PCM. In the magnetic tape device of this embodiment, this PCM (
:i, In the rare area 343, data obtained by adding an error correction code to digital data used in a computer or the like is recorded.

In the sub code areas 341 and 345, the magnetic tape 32
Search information, etc. for searching for a specific position of data on 9 is recorded. ATF signal area 342,
344 includes tracking control (the magnetic head runs on an inclined track with a corresponding azimuth angle during reproduction)
The ATF signal for is recorded.

In DAT, signals recorded on recording tape 329 are handled in units called data blocks. For example, the PCM signal area 343 is composed of 128 data blocks. The structure of the data block of the PCM signal area 343 is shown in FIG. One data block consists of 35 main data of 32 symbols (one symbol is 8 bits).
5, synchronization signal (SYNC) 351, main ID 352
, a block address 353, and one symbol each of a parity 354 for detecting errors in the main ID 352 and block address 353, making up a total of 36 symbols.

FIG. 17 shows a block configuration of the PCM signal area 343 in FIG. 15. It is composed of an I'CM signal area SYNC area 356, a main ID area @357, a block address area 358, a parity area 359, data consisting of the main data 355 of 128 data blocks, and an error correction code area 360. DAT
In this track format, the size of the data area excluding the error correction code, in other words, the capacity in which the user can record data is 2880 bytes per track.

In DAT, in order to perform data recording using the update-in-place method, data is recorded and reproduced on a magnetic tape in groups of multiple tracks. FIG. 18 shows the group format.

One group consists of 32 frames (2 tracks are called 1 frame, meaning 64 tracks). Three frames from frame 381 with frame number -3l to frame 328 with frame number -1 and frame 385 with frame number 28 are defined as gaps between groups.

28 frames from 384 to the 31st frame 384 whose frame number is 327 are used as an area for recording data. The frame number in the group is the frame number of the first frame in the area where data is recorded.
O l and numbered from '-3'' to '28'' as shown in FIG.

This frame number, along with the group number check described later,
Recorded in the aforementioned subcode areas 341 and 345,
Used for search.

FIG. 19 shows the structure of the area for recording group data. As explained in FIG. 18, this area ranges from frame number ○ frame 383 to frame number 2.
It consists of 28 frames up to frame 384 of 7.

In DAT, the data recorded on one track is 28
It is 80 bytes. Therefore, in 28 frames, 161
It will be 280 bytes.

Normally, an integral multiple of 256 bytes is used as a computer logical block. Therefore, of the 28 frames of data, 131072 bytes (256 x 512 bytes 1.
) is a data area (391 in the figure) that can be used by the user.

Of the remaining 30208 bytes, 4736 bytes are used by the magnetic tape device itself as a system area (392 in the figure)
25,464 bytes are used for 03 parity (393 in the figure) for error correction using the Reed-Solomon code. In the system area 392, it is impossible for the user to directly record or reproduce arbitrary data, and information for the magnetic tape device to manage the magnetic tape 329 is recorded therein. The remaining 8 bytes are left unused.

The C3 parity 393 for error correction is the magnetic tape 32
In order to correct data errors along the running direction of 9, continuous 8 Track Parse 1 - Data can be corrected even if an error occurs.

Each group is numbered and magnetically labeled. Also, this group number is the subcode area 341 mentioned above.
, 345.

In the magnetic tape device of this embodiment, even when data is recorded using the append method, recording is performed on the magnetic tape in units of grooves, similarly to data recording using the above-described upday 1 to in-place method. This is to improve data reliability by adding the C3 parity mentioned above. However, when recording data using the append method, the gaps in Figure 18 are not recorded. This is because the group that has been recorded once is not rewritten, so it is not necessary. That is, the group format when recording data using the append method consists of only 28 frames, from frame 383 with frame number O to frame 384 with frame number 327. Therefore, the configuration of the area in which group format data is recorded when data is recorded using the append method is the same as that of group format 1- when data is recorded using the update-in-place method. It will have the shape shown in the figure. FIG. 20 shows the configuration of the system area 392.

System area 392 has a size of 4736 bytes.

Of these, the first 4096 byes 1- are used for the record ID list area 394. Record ID list area 394
The attribute information of all records recorded in the group is recorded. A record is the minimum unit of data recorded on the magnetic tape 329. The following 512-byte area is designated as a reserved area 395. The reserved area 395 will be
This is an area reserved to enable functionality expansion. The last 128-byte area is used as a group ID 396, and group attribute information and the like are recorded therein.

Figure 21 shows the tape layout in the magnetic tape device of this embodiment. A load/unload area 401 is recorded at the beginning of the magnetic tape. Load/unload area 4
01 is an area in which the magnetic tape is loaded with magnetism. During the operation of loading or unloading magnetic tape into or from a rotating cylinder, there is a high possibility of damaging the magnetic tape. Therefore, the position determined for loading/unloading the magnetic tape to/from the rotating cylinder,
Here, the load/unload area 401 is used to ensure reliability of the area where the user records data. This is an area for recording information, and is composed of a preamble 405, a header 406, a reference 407, and a postamble 408.

The header 406 records fixed information of the magnetic tape, such as information regarding the time when the magnetic tape was started to be used and information regarding the format of the magnetic tape. Information regarding data recorded on the magnetic tape is recorded in the reference 407. The data area 403 is an area where the user records data. As mentioned above, when recording data using the group-in-place method, the group format (hereinafter referred to as group format O) with gaps before and after the group shown in FIG. When data is recorded using the group format shown in FIG. 18, the front and rear gaps are removed. The group format in which each group recorded in the data area 403 is recorded is recorded in a reference 407. Therefore, by referring to reference 407,
It is possible to determine in which group format a group with a certain group number is recorded, or in other words, whether or not it is possible to record data using the update 1 in-place method. EOI404 is
This group represents the end position of recorded valid data, indicating that no valid data is recorded after this point. When additionally recording data, record from the beginning of the already recorded EOI 404, that is, record the data following the end of the already recorded data, and add a new EOI 404 after the recorded data. Record. As a result, the EOI 404 always represents the end of valid data.

Also in this embodiment, the batza memory 325 is shown in FIG.
Use in the form shown in a). In other words, a flag is added to the block data sent from the host computer through the SCS I327 to indicate whether the block is a block for which data is recorded using the update-in-place method or a block for which data is recorded using the append method. The data is stored in the buffer memory 325 in the following form. Therefore, from the host computer to the buffer memory 325
The data transfer process to is shown in Figure 3(b),
Further, the process of transferring the data stored in the buffer memory to the magnetic tape is also shown in FIG.

Data transferred from a storage computer to be recorded on a magnetic tape is transferred in blocks. In the magnetic tape device of this embodiment, this block is recorded on the magnetic tape as a record in the above-described tape format. Therefore, multiple blocks are recorded in one group. In this embodiment, processing for recording data on magnetic tape will be explained. Consider a case where a host computer connected to a magnetic tape device records data in a group with group number n. The host 1 computer sends a write command to record data in the block 11 via the SCSI 327. Prior to this, the host computer checks whether the SCSI 327 bus is being used by another device, and if it is not being used, acquires the right to use it.

Next, the I of scsI given to the magnetic tape device of the present invention
Send D to the SCSI327 bus. The system control circuit 326 sends via the SCSI 327 the same SCSI ID assigned to it to the SCSI 327 bus.
When it detects that is being output, it receives a command from the host computer, in this case a write command. When the system control circuit 326 receives the write command, it instructs the drive control circuit 321 to enter "reproduction mode" in order to search for group n in which data is to be recorded, and controls the cylinder motor 316 and capstan motor 317 via the servo circuit 315. , and operate the reel motors 318, respectively. The data read by the read heads 311a and 31lb are sorted by the DAT signal processing circuit 319, and the data read from the subcode areas 341 and 345 is sent to the subcode control circuit 20, where an error check is performed. , sends this data to the system control circuit 326, and reads the current group number of the magnetic tape 329. If the current group number is smaller than the target group number n, a search is performed in the direction in which the group number increases (forward search, thick skew search). While the search is being performed, the host computer is waiting for data, so the SCSI32
7 buses will be occupied. Therefore, during this time, devices connected to other SCSI327 buses
It is no longer possible to use the I327 bus, and SCS
This will reduce the efficiency of using the I327 path. To avoid this, the system control circuit 326 sends the SCSI 327 to the host computer before performing the search.
Sends a save pointer message and a disconnect message instructing the disconnection of the system. When the host computer receives this message, it stores the memory address of the host computer where the data to be recorded on the magnetic tape 329 is stored in a predetermined memory, and temporarily stops using the SCSI 327 node. On the other hand, after sending this message, the system control circuit 326
The right to use the SCS I327 bus is temporarily relinquished. Therefore, in this state, the SCS I327 bus is unused and other services are available. In this manner, in the magnetic tape device, a search is performed with the SCSI 327 bus temporarily disconnected.

In the search, the magnetic tape 329 is run at 200 times the normal recording/reproducing speed, and the number of rotations of the rotating cylinder 310 is changed to the magnetic tape 329, the read head 311a, 31lb attached to the rotating cylinder 310, and the write head 312a, The data recorded in the subcode areas 341 and 345 are read, and the target group is detected.

After determining the direction of the search, the microcomputer 1 notifies the servo circuit 315 via the drive control circuit 321 of forward search or reverse search. The servo circuit 315 moves the magnetic tape 329 in the specified direction.
The reel motor 318 is operated to run at a speed of 00 times. The servo circuit 315 controls the sum of the supply-side fluxes of the magnetic tape 329 to a constant value. At the same time, the rotation of the rotary cylinder 310 is 3000rpm for forward search and 1000rpm for reverse search.
pm. At this time, the rotating cylinder 31
The read heads 311a and 31lb attached to the magnetic tape 329 cross a plurality of racks 1 and 1 on the magnetic tape 329. Depending on the azimuth of the read head, the signal of one rack with the same azimuth will have a large output, and the signal of a track with a different azimuth will have a small output, so by counting the number of large output signals, it is possible to You can know the number of tracks. Therefore, the reel motor 318 is controlled so that this number is constant.

In this state, the read heads 311a, 3]. The signal output from 1b is a part of the track, and DAT determines whether two blocks of subcode areas 341 and 345 provided in rack 1 have been read out consecutively without error.
The configuration is such that necessary information can be obtained by reading two consecutive blocks of data in the door areas 341 and 345 via the signal processing circuit 319. In other words, if two consecutive blocks have been correctly aligned, it is possible to know the group number in which the track is included.

The subcode control circuit 320 sends the correctly read block data of the subcode areas 341 and 345 to the system control circuit 326, and uses the group number included in the data recorded in the subcode area as the target. Compare with group number In. If they match, the microcomputer 1 instructs the servo control circuit 315 to "stop mode" via the drive control circuit 321, temporarily stops the reel motor 318, and returns the rotary cylinder 310 to 2000 rpm, which is the speed for normal data reproduction. After that, the magnetic tape 329 is moved to a position where the first rack of group number n can be played back using the reel motor 318 while inspecting the group number and frame number included in the data recorded in the subcode areas 341 and 345. Moving.

After this, the drive control circuit Il 1321 and the servo control circuit 315 are set to "reproduction mode", and the read signal is processed by the DAT signal processing circuit 319, and the data recorded in the subcode areas 341 and 345 is processed. is sent to the subcode control circuit 320, and PCM {A area 343
The data recorded in is sent to the DAT code decoding circuit 322. The subcode control circuit 320 is the subcode 34
By analyzing the data recorded in 1,345, the DAT code decoding circuit 322 is activated from the position of frame 383 whose frame number is O. The DAT code decoding circuit 322 starts operating in response to a signal from the subcode control circuit 320, and in playback mode decodes the received signal and stores the data for each track in the buffer memory 325 via the memory control circuit 323. ．． When data up to frame 384 with frame number 327 is stored in buffer memory 325, system control circuit 326 uses memory control circuit 323 and layered ECC circuit 324 to
3, error detection and error correction are performed. The error correction results are stored in the buffer memory 325 again.

After reading the data of group n into the buffer memory 325, the system control circuit 326 executes SCSI 327 bus selection and sends a reconnect message in order to receive data to be recorded from the host computer. The host computer that received this is SCS
Reconnect the I327 bus and transfer the data to the SCSI327
bus. The system-based alIUA path 326 receives this data via the SCSI 327, and stores it in the buffer memory 325 from the position where the data is to be recorded among the group n data read from the magnetic tape 329. When receiving these data, the system control port 326 can know the group number of the group in which the data is recorded based on the block number of the data. Therefore, by referring to the reference 407, it is possible to know whether the data in the block is data to be recorded using the update-in-place method or data to be recorded using the append method. In this embodiment, the difference between these two methods is the difference in group format when recording data. Blocks recorded using the update-in-place method are recorded in group format O, and blocks recorded using the append method are recorded in group format 1. The system control circuit 326 stores the received block data in the buffer memory 325. In this case, as shown in FIG. 4(a), an update-in-place flag or an append flag is stored in the flag area that stores the data of that block. After receiving the specified block of data, it is checked whether a parity error has occurred on the SCSI327 bus during the SCSI327 data transfer, and if the transfer was performed correctly, a good status is sent to the host computer. If a command complete message is sent, set a check condition in the status and set the error details in the sense data. Of course, when it receives a sense status command from the host computer, it sends out this data to notify the details of the error. The system control circuit 326 is connected to the buffer memory 32
Layered FCC for data stored in 5.
C3 parity 393 is added using circuit 324 and stored in buffer memory 325. The memory controller circuit 323 transmits this data to the DAT code decoding circuit 322, adds error correction parity determined within the DAT track, and outputs it to the DAT signal processing circuit 319 as serial data. The DAT processing circuit 319 that received this data performs 8-10 conversion of the data according to the data format in the track, and the verification circuit 314 converts the data according to the data format in the track.
At the same time, the signals are recorded on the magnetic tape 329 via the R/W circuit 313 by the write heads 312a and 312b. At this time, read heads 311a, 31lb
reads the data recorded by the write heads 312a and 312b and inputs it to the verify circuit 314 via the DAT signal processing circuit 319. The verify circuit 314 compares the recorded signal and the read signal to check whether they match. The number of unmatched numbers a for each track is sent to the system control circuit 326. The system control circuit 326 totals the number of mismatched signals for one group and checks whether the number is within a range where error correction is possible. A threshold that can be set by the user is used for this determination, and if the discrepancy is within N% of the error correction ability, it is assumed that the recording is correct and processing continues.

If a discrepancy in {rj exceeding this threshold hold is detected, this group is assumed to have not been recorded correctly and will not be used from now on, and instead the same group will be recorded next time. Therefore, when reading data, if the same group is read out consecutively, the group read out first is considered invalid and is skipped. Data recording on these magnetic tapes 329 is performed from data in blocks in the buffer memory 325 in which the append flag is set in the flag area, as shown in FIG. In either case, according to this embodiment, the magnetic tape device can identify, on the buffer memory, data in a block in which data is recorded using the update-in-place method and data in a block in which data is recorded in the append method. In order to record data in blocks that are to be recorded using the append method prior to data recording using the update-in-place method, recording of blocks that are to be recorded using the append method on magnetic tape is done in 1 step. This can be done by positioning to the recording start position once, and by reducing the number of times of positioning to the 8rA start position, it is possible to shorten the data recording time on the magnetic tape.

〔Effect of the invention〕

According to the control method of the magnetic tape device and the buffer memory connected thereto of the present invention, it is possible to rewrite data on the magnetic tape in the magnetic tape device and buffer memory that have the function of rewriting already recorded data. Even if there are areas that cannot be rewritten and areas that cannot be rewritten, the data to be recorded in each area is stored separately in the buffer memory, and the recording of data in the area to be rewritten is completed. To do it after. It is possible to reduce the number of times of positioning to the recording start position on the magnetic tape, and therefore it is possible to shorten the time required for data recording.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the flow of data recording processing for a magnetic tape device in a control system for a magnetic tape device and a buffer memory. FIG. 2 is a diagram showing an example of the configuration of a magnetic tape device in a control system for a magnetic tape device and a buffer memory connected thereto, and FIG. 3 is a diagram showing the flow of data storage processing in the buffer memory in an embodiment using flags. FIG. 5 is a diagram showing the processing flow of data transfer from the buffer memory to the magnetic tape, and FIG. 6 is a diagram showing an example of a tape format in a magnetic tape device using the magnetic tape device and buffer memory control method of the present invention. 7 is a diagram showing the contents of the buffer memory in an embodiment using flags, FIG. 8 is a diagram showing the configuration of the buffer memory in an embodiment in which the buffer memory is divided into two areas, and FIG. 9 is a diagram showing the buffer memory in an embodiment using flags. FIG. 10 is a diagram for explaining the conventional example.
The above figure is a diagram to explain how to use buffer memory.
FIG. 12 is a diagram for explaining how to use a buffer memory in a conventional example. FIG. 13 is a diagram showing the configuration of a magnetic tape device and a buffer memory in an embodiment in which the magnetic tape and buffer memory control method of the present invention is applied to a helical scan type magnetic tape device. FIG. 14 is a diagram showing a recording method on a magnetic tape in a helical scan type magnetic tape device, FIG. 15 is a diagram showing the configuration of racks 1 to 1 in a DAT, and FIG. 16 is a diagram showing the configuration of data blocks in a DAT. , FIG. 17 is a diagram showing the configuration of the data recording area in the DAT, FIG. 18 is a diagram showing the configuration of the group in the embodiment shown in FIG. 13, and FIG. 19 is a diagram showing the configuration of the data recording area of the group. , FIG. 20 is a diagram showing the configuration of a group system area, and FIG. 21 is a diagram showing the tape format of the magnetic tape used by the magnetic tape device of the embodiment shown in FIG. 13. 2... Data recording and update 1 using the append function
... Step of adding identification information with data recording using the in-place function, 3. Step of recording data using the append function, 4. Step of updating data 1 - Step of recording data using the in-place function, I1...Magnetic tape device. 12... Buffer memory, 66... Flag storage area, 327... SCS I, 325... Buffer memory, 402... Lead-in area, 403... Data area, 407... Reference. Figure 2 1 Cow 15 3rd (a) Figure 10 (12) Figure 3 (b) Atsushi cow (b) Leather 5 Dark leather 8 Figure 10 Figure 9 Figure 11 (ζS. (6) (C) 11th edition To chest 10 crop W9+B now's m Ka I+ World 329 15th figure b.7ku #father, kudzu 1ro figure 17 figure grass 19 figure 20

Claims (1)

[Claims] 1. A function to rewrite data already recorded on a magnetic tape (update in place function), and a function to record data from the end position of data already recorded on a magnetic tape (append function). a buffer memory connected to the magnetic tape device for temporarily storing data to be recorded on the magnetic tape; and an electronic computer connected to the buffer memory and using the magnetic tape device as an external storage device. In the system,
The data transferred from the computer system to the buffer memory for recording on a magnetic tape is determined whether the data is data to be recorded on a magnetic tape by an update-in-place function or recorded on a magnetic tape by an append function. The magnetic tape device is configured to store data in a buffer memory along with information indicating whether the data is data, and the magnetic tape device checks the information when retrieving data to be recorded on a magnetic tape from the buffer memory, and uses an append function to store data to be recorded on a magnetic tape. A control method for a magnetic tape device and a buffer memory, characterized in that the data to be recorded on the magnetic tape is recorded on the magnetic tape by an update-in-place function after all data is recorded on the magnetic tape. 2. In the magnetic tape device and buffer memory control method according to claim 1, data transferred from a computer system to the buffer memory for recording on a magnetic tape is transferred to a magnetic tape by an update-in-place function. The data is stored in the buffer memory along with a flag indicating whether the data is to be recorded on a tape or on a magnetic tape using an append function, and the magnetic tape device checks the flag when extracting data from the buffer memory, A magnetic tape device and a buffer characterized in that the data to be recorded on the magnetic tape is recorded on the magnetic tape using an update-in-place function after all data to be recorded on the magnetic tape is recorded on the magnetic tape using an append function. Memory control method. 3. In the magnetic tape device and buffer memory control method according to claim 1, the buffer memory is divided into a first area for storing data to be recorded on a magnetic tape by an update-in-place function, and a first area for storing data to be recorded on a magnetic tape by an append function. and a second area for storing data to be recorded on the tape, and after recording the data stored in the second area on the magnetic tape, the magnetic tape device records the data stored in the first area. A control method for a magnetic tape device and a buffer memory, characterized in that it is configured to record on magnetic tape.