JPH06131819A - Data writing method and data writing controller for helical scan recording magnetic tape device - Google Patents

Abstract

PURPOSE:To make efficient use of a medium by continuously writing a next group on the same stripe when the data length of the group, that is formed by writing headers and check data for each block of the data to be stored in a memory, does not come to a one stripe data length. CONSTITUTION:When a channel control section 2 receives a write command, an MPU 20 temporarily holds the transferred data in a control memory 3, adds headers and check data and forms one group. The data are checked by a byte counter 5 in a stripe and when the data do not reach 32K bytes which are the capacity of one stripe, accepts a next command and similarly processes. When it comes to 32K bytes by the next data, the MPU 20 sends respective groups to a data buffer 4 and the groups are stored as data of one stripe from a drive control section 6 through a drive 7. Thus, data of plural groups are written into a stripe and an efficient use of the medium is realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data writing method and a data writing control device in a magnetic tape device for helicopter scan recording, and more particularly to writing a plurality of groups of data in one stripe.

[0002]

2. Description of the Related Art For example, a mass storage system (Mass)
In the storage system, recording tracks are sequentially formed obliquely on a magnetic tape, and desired data is recorded at high density and reproduced, that is, a so-called heli-cal scan recording method is used to read and write data on the magnetic tape. In this case, a magnetic tape is wound around a rotating drum that rotates at a predetermined speed, and this magnetic tape is scanned at a predetermined speed, so that the magnetic head mounted on this rotating drum sequentially reads stripes that are recording tracks. It is configured to write.

That is, as shown in FIG. 11A, stripes TR1-0, TR1- are obliquely formed on the magnetic tape 1.
1 ... is formed. In fact, the stripe is
Although not shown, stripes TR1-0, TR2-0, TR3-0, TR4 are interleaved in units of four columns.
Next to −0, stripes TR1-1, TR2-1, TR3
-1, TR4-1 are located, followed by stripe T
R1-2, TR2-2, TR3-2, TR4-2 ...
The stripes are formed so that they are located. When one data is continuously written in a plurality of stripes, for example, stripe TR1-0 is followed by TR1-
1, TR1-2 ... are continuously written. That is, it is recorded at a 4-track cycle. Note that, in FIG. 11, such an interleaved state is omitted for simplification of description.

When data is stored on a magnetic tape by such a helicopter scan recording method, it is stored in one stripe unit. As shown in FIG. 11B, the data area D of one stripe TR1 can store 32 kbytes of data, and the data is stored in units of one stripe. Each stripe is provided with an attribute information area for storing attribute information a for recording information required for tape control and a check data area C for storing check data CRC. Here, in the attribute information area, the block I
D, the block length of data, and the like are stored.

When data is written on the magnetic tape 1 by the heli-cal scan method, as shown in FIG. 12, a data buffer 52 is provided in the magnetic tape read / write controller 51 so that the data output from the host processor 50 can be stored. After storing in the data buffer 52, one block is written in one stripe.

When the data of one block is 32 kbytes or more, as shown in FIG. 11C, the data that could not be written in the previous stripe TR1-0 is continuously written in the next stripe TR1-1. That is, first, referring to FIG.
First in the data area D of the stripe TR1-0 in (C)
The data Du of 32 kbyte length of the block is written, and the remaining data of the same block is transferred to the next stripe TR1-1.
The data area D is continuously written.

The attribute information a of the stripe TR1-0 includes
The block ID of the data stored in this stripe, the data length, continuous information indicating that the data continues to the next stripe, etc. are entered, and the check data area C
The check data CRC for the data stored in the stripe TR1-0 is written in. Then, in the data area D of the next stripe TR1-1, the remaining data Du of the same block that could not be written in the data area of the stripe TR1-0 is written. Stripe TR
In the 1-1 attribute information a, a block ID, data length, information indicating continuous information from the previous stripe, and the like are entered. Then, the dummy data Dd is written in the remaining portion of the data area, and the check data CRC is written in the check data area C.

When the data Du of one block has not reached 32 kbytes, as shown in FIG.
In the data area D of the stripe TR, the data Du of this block and the dummy data Dd are written. In the attribute information a, the block ID and the block length of the data are written, and the check data area C has the check data C.
RC is written.

[0009]

By the way, in such a conventional device, since only one block of data is written in one stripe, for example, one block of data is 10
In the case of k bytes, 22 kbytes of dummy data are stored. In this way, in one stripe of data, the dummy data may be larger than the required one block of data.

Storing a large amount of dummy data in one stripe is a wasteful process. Further, there is a problem in that the use of the tape for the dummy data is wasted in terms of capacity.

Therefore, an object of the present invention is to make it possible to write a plurality of blocks of data in each stripe and to significantly reduce the amount of dummy data, thereby effectively using the tape.

[0012]

In order to achieve the above object, according to the present invention, as shown in FIG. 1, when a channel controller 2 receives a write command from a host processor, the MPU
20 decodes this and subsequently holds the transmitted data in the control memory (CS) 3 once. And the header in which the attribute information is entered and the CR of the header
C is added to create one group, and this data is the capacity of one stripe with the byte counter 5 in the stripe.
Check if it has reached 2 kbytes. If it does not reach 32 kbytes, the next write command is received in the same manner, the transmitted data is held in the control memory 3, and the header in which the attribute information is written and its CRC are added. When the total of these data does not reach 32 kbytes, the next write command is received and the same process is performed.

When the data of the next block received reaches 32 Kbytes, the MPU 20 causes each of these groups to be sent to the data buffer 4, and is stored as one stripe of data from the drive control unit 6 via the drive 7. To do. At this time, in the drive control unit 6,
Create a CRC for the data of each of these groups,
This is also stored together.

[0014]

As described above, since data is written after the capacity of the data area of one stripe reaches 32 kbytes, the magnetic tape 1 has a plurality of groups (1) in one stripe as shown in FIG. The group can store attribute information, data of one block, check data, and the like). Therefore, since data of a plurality of blocks is stored in one stripe, the magnetic tape 1 can be effectively used.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIGS. FIG. 2 is a block diagram of an embodiment of the present invention.
Corresponding to the magnetic tape read / write device 51 in FIG. 3, FIG. 3 is an explanatory view (1) of the data storage state in the present invention, FIG. 4 is an explanatory view (2) of the data storage state in the present invention, and FIG. 5 is the present invention. Header, data, C
FIG. 6 is an RC explanatory diagram, FIG. 6 is a data storage state explanatory diagram (part 3) in the present invention, and FIGS.

In FIG. 2, the same symbols as in FIG. 1 indicate the same parts, 8 is a CRC control unit, 9 is a CRC control unit, 10 is a channel, 11 is a block counter, 12 is a data counter, and 13 is a flag setting unit. is there.

The channel control unit 2 controls input / output to / from the channel 10 and outputs the input data by M
In addition to sending to PU20 or CS3, the CRC control unit 8 performs a CRC check on the input data to correct a 1-bit error, and a multi-bit error is detected. Also, the CRC information added to this data is temporarily held.

The CS3 temporarily holds the data transmitted from the outside so as to be stored in the magnetic tape 1.
The PU 20 performs processing such as adding attribute information which is a header to the PU 20.

The data buffer 4 drives the data to which the attribute information, which is the header in the CS3, is added.
When storing in the stripe of magnetic tape 1 by
This is temporarily held from 3.

The in-stripe byte counter 5 counts the number of bytes of data stored in the stripe of the magnetic tape 1. The drive control unit 6 controls the drive 7 when reading / writing data from / to the magnetic tape 1, and the CRC control unit 9 controls the groups and stripes to be written on the magnetic tape 1 by the CRC control unit 9. A CRC is created and a CRC check is performed on the read data.

The drive 7 reads and writes the magnetic tape 1. The channel 10 inputs and outputs data to and from an external device such as a host. The block counter 11 creates a block ID number and increments by 1 each time a write command is input.

The data counter 12 is set with the write command and the byte length of the transmitted data. The flag setting unit 13 sets the flag portion of the header which is the attribute information of the group.

The MPU 20 not only comprehensively controls the entire magnetic tape read / write control device shown in FIG. 2, but also writes dummy data, calculates the CRC of the header, and monitors the timer 21 with a timer as described later. Processing such as write control is performed.

Before specifically explaining the operation of the present invention, the storage state of the stripe according to the present invention will be described. As is clear from the above description, the characteristic feature of the present invention is that the stripe TR is, for example, as shown in FIG.
First, the data of a plurality of groups G1 and G2 can be stored. Each group, as shown in FIG.
It is composed of a 32-byte header A, data Du stored in the data storage area, and 2-byte check data C for the header A and the data Du.

Therefore, in the case of FIG. 3A, the header A1
, A group G1 including data Du1 and check data C1, a header A2, data Du2, and check data C
A group G2 of 2 is stored in one stripe TR. In this case, as will be described later, since the data to be written is written before the data to be written to the remaining area is transmitted, the dummy data Du is written in the remaining portion of the stripe TR.

In FIG. 4, the data length of the magnetic tape 1 is 16k.
An example is shown in which a first group G1 of bytes and a second group G2 having a data length of 48 kbytes are written. First, in the stripe TR1, the header A1 of the first group G1 and the data D
u1 and check data C1 are written, and then the data of the second group G2 is written. In this case, since the data of the second group G2 can write only 16 kbytes, the second group G2 has G2-1 and G2. It is divided into -2 and written in the stripes TR1 and TR2. At this time, the header and the check data are written in each of the divided groups G2-1 and G2-2. Therefore, the second group G2 of 48 kbytes has the header A2-1, the data Du2-1 (16 kbytes), and the group G2-1 consisting of the check data C2-1 written in the stripe TR1, and the header A2-2, the data. D
A group G2-2 composed of u2-2 (32 kbytes) and check data C2-2 is written in the stripe TR2.

By the way, the header A in each group
Is attribute information to be entered, and as shown in FIG. 5A, a block I indicating a stored block number.
D, a data count indicating the byte length of the data Du, a flag, check data CRC of the header, etc., and is formed with a total length of 32 bytes.
Since it is formed with a bite length as shown in (A), 21
There is a byte reserve area.

By the way, this flag is formed by 1 byte as shown in FIG. 5A, and when the bit 0 (b0) is "1", it indicates the last data of the stripe, and the bit 1 ( When b1) is "1", it indicates that the following block data, that is, the data of one block, spans two or more stripes, and bit 2
When (b2) is "1", it indicates that the block data has continued from the previous stripe. Bits 3 to 7 are reserved and are all "0".

FIG. 5B shows a data storage area for storing the data Du. Only one block of data is stored in this area. Then, it is indicated that the check data C for this data Du is present following this data Du.

FIG. 6 shows a case where a large number of short one block data are written in one stripe. As shown in this figure, when multiple short blocks are sent,
For the convenience of management, data of up to 64 groups can be stored in one stripe so that the data storage area of one stripe does not overflow.
If the stored data is short and does not reach 32 kbytes, the dummy data Dd is stored in the rest.

In the present invention, as the timing for writing data to the magnetic tape 1, as described above, when the data to be stored reaches 32 kbytes, it is necessary to move the magnetic tape by reading, rewinding, or the like. There may be a case where a tape mark has to be written when another tape motion command is issued. The magnetic tape moves when another tape motion command is issued, so if the data held until then is not written, the write destination becomes incorrect. The tape mark indicates a file delimiter and is written according to an instruction from the host device, and is written on another stripe, and the magnetic tape also moves.

Data is written on the magnetic tape even if it does not reach 32 kbytes after a predetermined time has passed since the first request for writing. In this case, if the power supply is interrupted for a long time without holding the data on the magnetic tape and holding it in the CS or the data buffer, the data held in these will be erased. It is necessary to write on the magnetic tape within a certain period of time to prevent dribbling.

When another command of the motion type is issued or a tape mark is written, the data sent next is not written continuously to the stripe concerned, but from the new stripe next time. Write. However, you can continue writing as described below.

Next, the write operation of the data write control device of the present invention shown in FIG. 2 will be described with reference to the flow charts shown in FIGS. (1) The MPU 20 monitors whether a write command has been issued by the host device. When the write command is sent, it is decoded by the MPU 20 via the channel 10 and the channel controller 2. When the MPU 20 determines that it is a write command, it clears the in-stripe byte counter 5 to zero. Then, the MPU 20 sends the one block of data sent together with this write command from the channel 10 to the channel control unit 2, and the CRC
An error check is performed by the control unit 8. Then MPU
20 sends the data from the channel control unit 2 to the CS 3 and holds it. At this time, the MPU 20 uses the block counter 1
The block ID is updated by incrementing 1 by 1. And MPU2
For 0, the number of bytes of one block indicated by this write command is stored in the data counter 12.

(2) At this time, the MPU 20 determines whether bit 1 in the flag setting unit 13 is set (b1 = "1"), and if not set, decrements the data counter 12 by -1. . If it is set, the data sent at this time is judged to be continuous data of the previous data, and bit 2 of the flag in the flag setting unit 13 is set (b2 = "1") and this data is Indicates a continuation of the previous data. And M
The PU 20 also decrements the data counter 12 by -1.

(3) If the data counter 12 is not zero even after the data counter 20 is decremented, the MPU 2
For 0, it is checked whether the byte counter in stripe 5 is 32k.

(4) The byte counter 5 in the stripe is 32
If not k, the MPU 20 increments the byte counter in stripe 5 by +1. And again above (2),
Returning to (3), the data counter is decremented by 1, and the same processing is repeated.

(5) In the above (3), if the data counter 12 becomes zero, this means that the down-counting of the data length in one block is completed. At this time, the stripe byte counter 5 counts 32 k. Check if it is counting. If 32k is not counted, the process shown in FIG. 8 is performed.

(6) As shown in FIG. 8, the MPU 20 sets the header of the group, that is, the block ID from the block counter 11, the data count from the number of bytes of one block transmitted together with the write command, and the flag setting. The flag state from the unit 13 is set in the header of the data held in CS3, the check data (CRC) of the header is calculated and added to the header. Then, the data in this one group is sent from CS3 to the data buffer 4. Next, the MPU 20 adds the check data C (transmitted via the channel 10) to the data created and held by the channel control unit 2. Also, a group of check data (CRC) created by the CRC control unit 9 is added. Then, the routine proceeds to the routine shown by B in FIG. 7 and waits for the next data input from the channel 2.

(7) In (5) above, if the byte counter in stripe 5 counts 32k, then 32k
It means that byte data is stored. Therefore,
Since that data is the last data in one stripe, bit 0 in the flag setting unit 13 is set (b0
= “1”), and the processing shown in FIG. 9 is performed.

(8) As shown in FIG. 9, the MPU 20
The header of the group is set for the data held in No. 3 in the same manner as in (6) above, and the check data (CRC) of this header is calculated and added to the header. Then, one stripe of data is sent to the data buffer 4. Check data (CRC) created by the channel controller 2 is added to this. Also C
The check data (CR
C) is added. Data of one stripe is sent from the data buffer 4 to the drive control unit 6. The drive control unit 6 adds data, that is, check data (CRC) of data for the entire one stripe. Then MPU2
0 requests the drive control unit 6 to write on the magnetic tape 1. As a result, the drive 7 shown in FIG. 2 writes data on the magnetic tape 1. At this time, if bit 1 of the flag setting unit 13 is not set (b1 = "1"), the routine proceeds to the routine of A in FIG. 7 and waits for a write command to be issued. However, if it is set, it indicates the existence of continuous data, and the routine proceeds to C of FIG.

(9) By the way, in the above (4), the in-stripe byte counter 5 counts 32 k and then 32 k
If the storage of bytes is indicated, data continues to exist, so that bit 1 in the flag setting unit 13 is set (b1 = "1") to indicate that continuous data exists, as shown in FIG. The routine will shift to the routine of D. In this way, the write processing is performed.

Further, according to the present invention, when a tape motion type command is used to position the block in the middle or the last block of the tape, and subsequently a command for writing data to the tape is issued, the stripe in which the block is stored is stored. Can be stored in the middle of the stripe by expanding the data on the buffer or on the CS and knowing the configuration of the stripe.

For this reason, as shown in FIG. 10, when a tape motion command is issued, the block ID is read from the block counter 11 at that time and held in CS3. Then, when a write command is issued, the MPU 20 reads the data of the stripe by the drive control unit 6 based on the block ID held in the CS3. Then, the read data is written in the data buffer 4.

Then, the MPU 20 takes out the information of the header of the data written in the data buffer 4 and determines the data count value of the stripe. The data count value obtained in this way is stored in the stripe byte counter 5. By shifting to the routine of B in FIG. 7, the data can be stored from the middle of the stripe as described above.

The MPU 20 monitors the issuance of a tape motion type command, and if unwritten data remains on the magnetic tape at the time of issuance, the MPU 20 executes the command by the routine shown in FIG. Store on magnetic tape. Even when the tape mark must be written, the MPU 20 monitors this and similarly stores the blank data on the magnetic tape. Then, timer monitoring is performed by the timer 21, and if there is unfilled data even after a certain period of time, it is similarly stored in the magnetic tape. Further, by counting the number of blocks stored in the CS, when the number of unwritten blocks becomes, for example, 64, these are similarly stored in the magnetic tape.

[0047]

As described above, according to the present invention, since only one block of data can be stored in one stripe in the past, a plurality of blocks can be stored in one stripe. You can write. As a result, the process of storing the dummy data can be minimized, and the medium can be used very effectively.

[Brief description of drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a configuration diagram of an embodiment of the present invention.

FIG. 3 is an explanatory diagram (part 1) of a data storage state in the present invention.

FIG. 4 is a diagram (part 2) explaining a data storage state in the present invention.

FIG. 5 is an explanatory diagram of a header, data, and CRC according to the present invention.

FIG. 6 is an explanatory diagram (part 3) of a data storage state in the present invention.

FIG. 7 is a flowchart (No. 1) for explaining the operation of the present invention.

FIG. 8 is a flowchart (No. 2) for explaining the operation of the present invention.

FIG. 9 is a flowchart (No. 3) for explaining the operation of the present invention.

FIG. 10 is a flowchart for explaining the operation of the present invention (part 4).
Is.

FIG. 11 is an explanatory diagram of a conventional example.

FIG. 12 is a schematic diagram of a data processing device.

[Explanation of symbols]

 1 magnetic tape 2 channel control unit 3 control memory (CS) 4 data buffer 5 byte counter in stripe 6 drive control unit 7 drive 20 MPU

Claims (7)

[Claims] 1. A magnetic tape device for performing helicopter scan recording on a magnetic tape (1), comprising a counting means (5) for counting the length of data to be written in a stripe (TR), and a data holding means (3). ), A group in which a header and check data are written is formed for each block of data stored in (1), and the data length to be written in one stripe is counted by the counting means (5), and the data length depends on one group. If it does not reach, the data writing method is characterized in that a plurality of groups can be written in one stripe by successively writing the next group in the same stripe. 2. The data writing method according to claim 1, wherein the header is provided with a flag indicating that data is continuing to the next stripe and a flag indicating that data is continuing from the previous stripe. . 3. A magnetic tape apparatus for performing helicopter scan recording on a magnetic tape (1), a counting means (5) for counting the length of data to be written in a stripe (TR), and a block ID. Block counting means (11) and counting means (12) indicating the length of data in the block
A flag setting means (13) and a data holding means (3) are provided, the block ID obtained by the block counting means (12), the data length shown in the counting means (12),
A flag shown in the flag setting means (13) is written in the header to form a group header to indicate the head of the group, and a plurality of groups in one stripe up to the count length determined by the counting means (5). A data write control device characterized in that data is writable. 4. A tape mark write command detection means is provided, and when a tape mark write command is issued,
4. The data write control device according to claim 3, wherein the next data to be sent is not written next to the stripe concerned but is newly written in the next stripe. 5. The data writing control device according to claim 3, wherein a timer is provided, and when there is unwritten data for a certain period of time, the data is written on the magnetic tape. 6. A means for counting the number of blocks of unwritten data on the magnetic tape is provided, and the number of groups that can be stored in each stripe is set so that the data storage area of one stripe does not overflow. 4. The data write control device according to claim 3, wherein the data write control device can be limited. 7. A tape motion type command detecting means is provided, and when a tape motion type command is used to position a block in the middle or the last block of the magnetic tape and subsequently a command to write data to the magnetic tape is issued, 4. The data write control device according to claim 3, wherein the stripe storing the block is expanded on the buffer and the structure of the stripe is known so that the data can be stored from the middle of the stripe.