JP2792341B2 - Disk controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk controller for controlling a disk drive having one or more logical tracks formed on a physical track, and more particularly to a disk controller for reading one logical track from a higher-level device. The present invention relates to a disk control device which reduces the load on a host device and improves the read processing efficiency.

2. Description of the Related Art In a magnetic disk device used as an external storage device of a computer system, a record in which a data length recorded in a count section indicates zero, that is, an end of record, is controlled by an operating system (OS).
Using the file (EOF), one or more logical tracks are created on the physical track, and the read track
Reading of this logical track may be instructed by a command chain including a command.

When a magnetic disk controller issues a read track command, it cannot distinguish between a physical track and a logical track. Although all records up to the upper end are read, it is desirable to avoid reading records on unnecessary logical tracks.

[0004]

2. Description of the Related Art When a command chain including a read track command is issued from a central processing unit of a computer system to a magnetic disk control device, conventionally, a command chain following a record to be searched on a physical track of the magnetic disk device is conventionally used. All records from the record to the end on this physical track are read and transferred to the central processing unit.

Therefore, even when a plurality of logical tracks are created on a physical track using EOF under the control of the OS, all records subsequent to the record following the record to be searched on the physical track have been read.

[0006]

As described above, conventionally,
When the central processing unit creates one or more logical tracks on the physical track of the magnetic disk device and reads all records from one of the logical tracks, once the record next to the record to be searched on the physical track After reading all records up to the end on this physical track, a process for extracting records on the logical track required by the central processing unit is required.

Therefore, the load on the central processing unit increases, and unnecessary records on the physical tracks are read in addition to the records on the necessary logical tracks, so that useless time is required and the read processing efficiency is reduced. There is a problem.

The present invention has been made in view of such a problem, and by specifying from a central processing unit whether a read track command is valid for a physical track or a logical track, It is an object of the present invention to enable a magnetic disk controller to read only records on logical tracks required by a central processing unit.

[0009]

FIG. 1 is a block diagram for explaining the principle of the present invention. The disk control device 2 controls a disk device 3 in which one or more logical tracks separated by an end of file are formed on a physical track, and includes a command including a read track command issued by the host device 1. Reads the specified record based on the chain.

When receiving the command chain provided with a flag indicating whether the read track command is valid for a physical track or valid for a logical track, Read the record on the physical track, or
Control means 4 for determining whether to read a record on one logical track is provided.

If this flag makes the read track command valid for a physical track, the total number of times from the record following the record to be searched on the physical track to the end on the physical track is determined. If this flag makes the read track command valid for a logical track, the end-of-record read first from the record following the record to be searched on the physical track is read. Read all records up to the file.

[0012]

With the above-mentioned configuration, the host device 1 specifies whether to read a physical track record or a logical track record by using a flag provided in the command chain.
With this control, only the record of the designated logical track can be read.

Therefore, since only the records of the logical tracks required by the higher-level device 1 are read, unnecessary records are not read, the read processing efficiency is improved, and the records required by the higher-level device 1 are stored. Since the extraction process is not required, the burden on the host device 1 can be reduced.

[0014]

FIG. 2 is a block diagram of a circuit showing one embodiment of the present invention, and FIGS. 3 to 6 are diagrams for explaining the operation of FIG.

The processor 8 of the disk controller 2 reads and operates the program stored in the control memory 9 and operates a command chain transmitted by the host device 1 through the interface circuit 5, for example, a DX (Define Eetent) (later described). Command for specifying the following operation), LR (Locate Recor
d) When a command for instructing a write or read operation and an instruction for searching for a record to be processed is received, and RT (Read Track) (a command for instructing track read) is received, the disk device 3 is controlled via the interface circuit 7. , LR
Position the head on the cylinder specified by.

Then, the flag provided in the LR is checked.
It is checked whether this command indicates that it is valid for a physical track or that it is valid for a logical track.

If it is valid for the physical track, the record number of the count section of the record read from the track followed by the designated head positioned at the designated cylinder is checked, and the designated record number is determined. When the LR instructs the reading, when the LR instructs the reading, the interface circuit 7 transmits the data from the record read next to the search target record to the last record of the track followed by the head. The data is transferred to the host device 1 via the transfer control circuit 6 and the interface circuit 5.

FIG. 3 shows an example of a physical track.
On the physical track 10 shown in (A), a home address HA is recorded following an index, and a plurality of records are subsequently recorded from record R (0) to record Rn + 2.

Accordingly, the processor 8 determines that the record R (1) shown in FIG.
As shown in (1), all records from the record R (2) to the record Rn + 2 are transferred as described above.

FIG. 4 shows a case where one logical track is provided on the physical track 10. As shown in FIG. 4A, a record R (1) is a search target record and a record Rn is an EOF. Then, the processor 8 checks the flag provided in the LR, and if this command indicates that the command is valid for the logical track, the processor 8 converts the record R (2) from the record R (2) as shown in FIG. All records up to Rn are transferred to the host device 1.

That is, the processor 8 recognizes the end of the logical track since the data length recorded in the count section of the record Rn is zero, and instructs the data transfer control circuit 6 to execute the data transfer control circuit 6. The transfer of the record read from the next record is stopped.

FIG. 5 shows that the home address HA is recorded on the physical track 10 following the index, and then a plurality of records are recorded from the record R (0) to the record Rn. Shows a case where a plurality of symbols are provided.

Then, as shown in FIG.
Assuming that (1) is a record to be searched and that records Rk, Rm, and Rn are EOF, the processor 8 returns to FIG. 5B if the flag indicates that the flag is valid for the physical track. As shown, record R (2)
All records from the record to the record Rn are transferred to the host device 1.

FIG. 6 shows a case where a plurality of logical tracks are provided on the physical track recorded from the record R (0) to the record Rn. As shown in FIG. Assuming that record Rk, record Rm, and record Rn are EOF in the search target record, the processor 8 determines that the record is valid as shown in FIG. R
All records from (2) to record Rk are transferred to the host device 1.

That is, since the processor 8 reads the record R (1) to be searched, the EOF read first, that is, the data length recorded in the count portion of the record Rk indicates zero. , This record Rk is EO
If it is determined to be F, the end of the logical track is recognized, and the data transfer control circuit 6 is instructed to stop the transfer of the record read from the record next to the record Rk.

As shown in FIG. 6C, if Rk is a record to be searched and records Rk, Rm and Rn are EOF, the processor 8 determines that the flag is valid for the logical track. In this case, as shown in FIG. 6D, since the data length of the count portion of the record Rm is zero as in the above case, it is determined that the EOF has been read first, and the records Rk + 1 to Rm are determined.
All records up to this point are transferred to the host device 1.

As shown in FIG. 6E, if Rm is a record to be searched and records Rk, Rm, and Rn are EOF, the processor 8 determines that the flag is valid for the logical track. In this case, as shown in FIG. 6 (F), all records from the record Rk + 1 to the record Rn are transferred to the host device 1.

FIG. 7 is a flowchart for explaining the operation of FIG. The processor 8 monitors the reception of the command chain in step (1), and upon receiving the command chain, positions the head at the cylinder specified in step (2).

Then, in step (3), the completion of the positioning of the head is waited. When the positioning of the head in the designated cylinder is completed, it is checked in step (4) whether the data is read or not. In (5), check whether the flag indicates that the physical track is valid.

If the flag indicates that the physical track is valid, all the records from the record read after the record to be searched in step (6) to the last record of this track are read, and 1 Then, the process returns to the step (1).

If the flag does not indicate that the physical track is valid but indicates that the logical track is valid in step (5), then in step (7), from the record read next to the search target record, EO read first
All records up to F are transferred to the host device 1. Then, the process returns to the step (1).

If the data writing is instructed in step (4), the processor 8 proceeds from step (8) to the next record after the search target record to the designated record.
The data sent from the host device 1 is written. Then, the process returns to the step (1).

[0033]

As described above, according to the present invention, when a logical track is created on a physical track, only the record of the logical track required by the host device is read, so that unnecessary records are not read. In addition, the read processing efficiency is improved, and the process of extracting records required by the higher-level device is not required, so that the burden on the higher-level device can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a block diagram of a circuit showing one embodiment of the present invention.

FIG. 3 is a view for explaining the operation of FIG. 2 (part 1);

FIG. 4 is a diagram (part 2) for explaining the operation of FIG. 2;

FIG. 5 is a view (part 3) for explaining the operation of FIG. 2;

FIG. 6 is a view for explaining the operation of FIG. 2 (part 4);

FIG. 7 is a flowchart for explaining the operation of FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper device 2 Disk controller 3 Disk device 4 Control means 5, 7 Interface circuit 6 Data transfer control circuit 8 Processor 9 Control storage 10 Physical track

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Claims (1)

(57) [Claims] A read track command which is controlled by a disk device (3) in which one or a plurality of logical tracks separated by an end of file are formed on a physical track and is issued by an upper device (1) In the disk control device (2) that reads a specified record based on a command chain that includes a command chain, whether the read track command is valid for a physical track or valid for a logical track. When receiving the command chain provided with a flag designating a flag, the control means (4) determines whether to read a record on a physical track or a record on one logical track based on the flag. If the flag makes the read track command valid for a physical track, a service on the physical track Read all records from the record following the current record to the end on the physical track, and if the flag indicates that the read track command is valid for a logical track, A disk control device for reading out all records from a record next to the search target record to the end of file read out first.