JPH05324475A - Magnetic disk sub system - Google Patents

Abstract

PURPOSE:To shorten processing time at the time of executing a data write command by interrupting a read operation and writing sent data in a magnetic disk device when data under reading are coincident with a search instruction. CONSTITUTION:When the data of an object track are not existent at a memory part 10 of a cache controller, it is checked in a data check part 60 by using the search instruction whether data read at the time of reading track data are coincident with search conditions or not. When the coincidence is reported, a cache R/W control part 30 of a controller for a magnetic disk reads the next command and when the command instructs the read of data, the execution start of the next command is waited in the magnetic disk controller until the track data are completely read. On the other hand, when the command instructs the write of data, the interruption of the track data read operation is instructed, and the write command is directly executed to the magnetic disk device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk subsystem, and more particularly to a cache processing method during device write.

[0002]

2. Description of the Related Art Conventionally, a system for transferring data between a host computer (hereinafter abbreviated as host) and a magnetic disk device (hereinafter abbreviated as DKU) using a disk cache is shown in FIG. As shown in the figure, a magnetic disk controller (hereinafter abbreviated as DKC) for controlling the DKU is connected to the host, and a cache controller (hereinafter abbreviated as DCC) having a memory inside is connected to the magnetic disk controller.
, And connect the DKU under the DCC.

To read the data of DKU, D from the host
When a seek command is issued to the KC, the DKC requests the DCC for the data of the track designated by the seek command, and the DCC does not have the data of the requested track in the memory in the DCC (in the cache. Don't hit)
At this time, the DCC informs the DKC that there is no data, reads the data of the track requested by the DKU, stores it in the memory in the DCC, and when the storage is over, the DCC informs the end of the DKC read. Then DKC
Reads a command for reading data from the host, reads the data specified by the command for reading data from the memory of the DCC, and transfers the data to the host.

With this configuration, the host can make the DCC
If there is a data transfer request (read request) for the track data stored in the memory, the mechanical operation is better to read and transfer the data from the memory than to read and transfer the data from the DKU. Since it is not accompanied, data can be transferred very quickly. Such a method is called a cache method. On the other hand, when the host issues a seek command to the DKC to write data to the DKU, the DKC requests the DCC for the data of the track specified by the seek command, and the DCC requests the data of the requested track. , Is not in memory in the DCC, DC
The C notifies the DKC that there is no data, reads the data of the track requested by the DKU, stores the data in the memory in the DCC, and when the storage is completed, the DC
C signals the end of DKC reading. Then, the DKC reads the search command from the host and directly executes the search command to the DKU. When the search results match, the DKC writes the data instructed by the host to the DKU.

[0005]

In a system which does not support a cache memory, the time required to write data to the DKU is the time required to write the data sent from the host (usually the DKU rotates once). (Less than the time it takes to complete) (excluding seek time and rotation waiting time for search).

However, in the above-mentioned conventional cache system, when data is not written to the cache, in order to write the data to the DKU, the time for reading the data of the track to the cache memory (one rotation of the DKU) and the data are magnetically read. There is a problem that the sum of the time for writing to the disk device, that is, the processing time of one rotation of the DKU or more is required, and the processing time becomes slower than that of the system which does not support the cache.

[0007]

A magnetic disk subsystem according to the present invention includes a magnetic disk controller connected to a central processing unit, at least one magnetic disk device controlled by the magnetic disk controller, and A magnetic disk subsystem comprising a cache controller provided between the magnetic disk controller and the magnetic disk device and capable of caching information stored in the magnetic disk device, and reading from the magnetic disk device. Memory section for storing the data, a command control section having the following functions, and a seek instruction from the magnetic disk control device, and the memory section has the data of the track instructed by the seek instruction. If there is no data in the memory section as a result,
Notifying the magnetic disk controller of this fact and issuing an instruction to read the track data specified by the seek instruction to the magnetic disk device when there is no data in the memory section.

A data writing instruction to the magnetic disk device is issued to the magnetic disk device based on a data writing instruction from the magnetic disk control device to the magnetic disk device. A seek command is issued to the magnetic disk device based on a cache R / W control unit having the following functions and an instruction to read the track data of the magnetic disk device from the command control unit. After this, when a seek end report is received from the magnetic disk device, the fact is notified to the magnetic disk control device, and the data of the instructed track is read from the magnetic disk device and written in the memory section.

On the basis of the data write instruction from the command controller, the read operation instructed by the track data read instruction is interrupted and the data sent from the magnetic disk controller is written to the magnetic disk device. thing.

An upper interface unit for transferring data between the cache R / W control unit and the magnetic disk controller, and a lower interface unit for transferring data between the cache R / W control unit and the magnetic disk unit. And a data check unit having the following functions to instruct the magnetic disk control device to search for a target record on the track of the magnetic disk device (search command).
On the basis of the above, the cache R / W which is reading the data of the magnetic disk device according to the track data read instruction.
Monitor the controller to see if the data being read matches the previous search instruction.

As a result of the check, when the record instructed by the search instruction is detected, the search coincidence during data reading is notified to the magnetic disk controller. It is characterized by having.

Further, a seek command is issued to the cache controller upon receipt of a seek command for the magnetic disk unit from the access command controller having the following functions and the central processing unit.

Upon receipt of a seek end notification from the cache controller to the track designated by the seek instruction,
Read the next command, a search instruction, from the central processing unit and send the search instruction to the cache control unit. Command check part with the following functions,
Read the next command from the central processing unit upon receiving a notification from the cache control unit that the search match during data reading.

It is judged whether the next command is an instruction to write or read data to the magnetic disk device, and if it is an instruction to read data, the execution of the next command is started. Waiting inside, and executing the next command when the cache control device finishes the read operation of the track data.

On the other hand, in the case of a data write instruction, a write command execution instruction should be sent.

According to a write command execution instruction from the command check unit, a write command execution unit for reading data to be written in the magnetic disk device from the central processing unit and transferring it to the cache control unit, and the write command execution unit and the central processing unit. It is characterized by having a system interface section for exchanging data between them, and a device interface section for exchanging data between the write command execution section and the cache control device.

[0017]

EXAMPLES Next, the present invention will be explained based on examples.

FIG. 1 is a block diagram showing an embodiment of the present invention.

The memory section 10 is a section for storing data read from the magnetic disk device, the command control section 2
0 receives a seek instruction from the magnetic disk control device, and checks whether or not the data of the track designated by the seek instruction exists in the memory section 10, and as a result,
If there is no data in the memory section 10, the magnetic disk controller is notified of this fact and an instruction to read the track data specified by the seek instruction is issued to the magnetic disk device. A portion for issuing a data write instruction to the magnetic disk device to the magnetic disk device based on the data write instruction to the device, the cache R / W control unit 30.
Issues a seek command to the magnetic disk device based on an instruction to read the track data of the magnetic disk device from the command control unit 20. When a seek end report is received from the magnetic disk device, the magnetic disk device notifies the fact. The memory unit 1 is notified while notifying the control device and reading the data of the instructed track from the magnetic disk device.
0, and the read operation instructed by the track data read instruction is interrupted based on the data write instruction from the command control unit 20, and the data sent from the magnetic disk controller is written. Writing to the magnetic disk device, the upper interface unit 40 transfers data between the cache R / W control unit 30 and the magnetic disk control device, and the lower interface unit 50 operates the cache R / W. W control unit 30
And the part that transfers data between the
The data check unit 60 monitors the cache R / W control unit 30 which is reading data of the magnetic disk device according to the track data read instruction based on the search instruction from the magnetic disk control device to the magnetic disk device,
It is checked whether the data being read matches the previous search instruction. As a result, when the record instructed by the search instruction is detected, the search match during data reading is notified to the magnetic disk controller. It is a part.

The access command control unit 100 receives a seek command from the central processing unit to the magnetic disk unit, issues a seek instruction to the cache control unit, and seeks from the cache control unit to the track instructed by the seek instruction. Upon receipt of the end notification, the central processing unit reads the next command, the search instruction, and sends the search instruction to the cache control unit. The command check unit 110 is a unit that reads the data from the cache control unit. In response to the notification of search match, the next command is read from the central processing unit, and it is judged whether the next command is an instruction to write data to the magnetic disk device or an instruction to read data, and the data is read. When instructed, the execution of the next command is started by the magnetic disk controller. In waiting advance, when the cache controller completes the read operation of the track data,
The following command is executed. On the other hand, in the case of a data write instruction, the write command execution section 120, which is a part that sends out a write command execution instruction, writes the data to be written to the magnetic disk device to the central processing unit according to the write command execution instruction from the command check section 110. A part for reading and transferring to the cache control device, a system interface part 130 for transferring data between the write command execution part 120 and the central processing unit, and a device interface part 140 for the write command execution part 120. This is a part for passing data between the cache control devices.

When there is a seek command from the central processing unit to the magnetic disk controller under control of the magnetic disk controller, the access command control unit 1 which has received this seek command.
00 issues a seek instruction for requesting the data of the track instructed by the seek instruction to the cache controller through the device interface 140. The command control unit 20 having received the seek instruction from the magnetic disk control device through the host interface 40 checks whether the data of the track designated by the seek instruction exists in the memory unit 10, and there is no data of the designated track. In this case, the fact that there is no data is notified to the magnetic disk controller through the upper interface 40. Further, the command control unit 20 instructs the cache R / W control unit 30 to read out the track data designated by the seek instruction. The cache R / W control unit 30 which has received the track data read instruction issues a seek command to the connected magnetic disk device through the lower interface 50, and when a seek end report is returned from the magnetic disk device, this fact is notified. To the magnetic disk controller. Then, based on the track data read instruction, the operation of reading the instructed track data and the operation of writing the read data to the memory unit 10 are started. The access command controller 100, which has received the seek end report from the cache controller through the device interface 140, reads the next command, a search instruction, from the central processing unit through the system interface 130,
The search instruction is sent to the cache control device through the device interface 140. Upper interface 40
The data check unit 60, which has received the search instruction from the magnetic disk control device through the above, monitors the cache R / W control unit 30 which is reading the data of the magnetic disk device according to the track data read instruction, and the data being read is checked. It is checked whether or not it matches the previous search instruction, and when a record instructed by the search instruction is detected, the search agreement during data reading is notified to the magnetic disk control device through the host interface 40. The command check unit 110, which has received the search match during reading through the device interface 140, reads the next command from the central processing unit through the system interface 130, and whether the next command instructs writing of data to the magnetic disk device. Whether or not it is a read instruction is judged, and if it is a data read instruction, execution start of the next command is waited in the magnetic disk controller until the cache controller finishes the track data read operation. On the other hand, in the case of a data write instruction, a write command execution instruction is given to the cache control device through the write command execution unit 120 and the device interface 140. The write command execution unit 120, which has received the write command execution instruction, reads the data to be written in the magnetic disk device from the central processing unit through the system interface 130 and transfers it to the cache control unit through the device interface 140. Upper interface 4
Upon receiving the write command execution request through 0, the command control unit 20 issues a data write instruction to the magnetic disk device. The cache R / W control unit 30 receiving the data write instruction suspends the read operation instructed by the track data read instruction. Then, the data to be written in the magnetic disk device sent through the upper interface 40 is directly written in the magnetic disk device.

[0022]

As described above, according to the present invention, when the data of the target track does not exist in the memory of the cache controller, the cache controller uses the search instruction sent from the magnetic disk controller to perform magnetic At the same time, it is checked whether the data read during the track data read operation from the disk device matches the search condition.

When a coincidence report is received, the magnetic disk control device reads the next command, and when this command is an instruction to read data from the magnetic disk device, the cache control device continues until the read operation of track data is completed. The start of execution of the command is waited in the magnetic disk control device. On the other hand, in the case of a data write instruction, the interruption of the track data read operation is instructed, and the write command is directly executed to the magnetic disk device. As a result, it is possible to reduce the extra rotation time when executing the data write command, and there is an advantage that the processing time can be shortened.

[Brief description of drawings]

FIG. 1 shows a block diagram of an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a magnetic disk subsystem using a cache.

[Explanation of symbols]

 10 memory unit 20 command control unit 30 cache Read / Write control unit 40 upper interface 50 lower interface 60 data check unit 100 access command control unit 110 command check unit 120 write command execution unit 130 system interface 140 system check unit

Claims (2)

[Claims] 1. A magnetic disk control device connected to a central processing unit, at least one magnetic disk device controlled by the magnetic disk control device, and between the magnetic disk control device and the magnetic disk device. In a magnetic disk subsystem provided with a cache control device capable of caching information stored in the magnetic disk device, a memory unit for storing data read from the magnetic disk device, and Upon receipt of a seek instruction from the command control unit having the indicated function and the magnetic disk control device, it is checked whether or not the data of the track designated by the seek instruction exists in the memory unit. If there is no data, the magnetic disk controller is notified of this fact and the seek instruction Reading instruction track data be output to the magnetic disk device. An instruction to write data to a magnetic disk device is issued to the magnetic disk device based on an instruction to write data to the magnetic disk device from the magnetic disk control device. A seek command is issued to the magnetic disk device based on a cache R / W control unit having the following functions and a read instruction of the track data of the magnetic disk device from the command control unit, and thereafter a magnetic disk device is issued. When the seek end report is sent from the magnetic disk controller, the fact is notified to the magnetic disk controller, and the data of the instructed track is read from the magnetic disk device and written in the memory section. Based on the data write instruction from the command control unit, the read operation instructed by the track data read instruction is interrupted, and the data sent from the magnetic disk control device is written to the magnetic disk device. An upper interface unit that transfers data between the cache R / W control unit and the magnetic disk control device; a lower interface unit that transfers data between the cache R / W control unit and the magnetic disk device; And a data check unit having the function shown in FIG. 1, based on an instruction (search instruction) from the magnetic disk control device to search for a target record on a track of the magnetic disk device. To monitor the cache R / W control unit being read, and check whether the data being read matches the previous search instruction. As a result of the check, when the record instructed by the search instruction is detected, the magnetic disk controller is notified of a search match during data reading. A magnetic disk subsystem including a cache control device having. 2. An access command control unit having the following functions, and a seek instruction to the cache control unit upon receiving a seek command from the central processing unit to the magnetic disk unit. Receiving a notification from the cache control device of the end of seek to the track designated by the seek instruction, the central processing unit reads the next command, the search instruction, and sends the search instruction to the cache control apparatus. A command check unit having the following functions, and reading the next command from the central processing unit upon receipt of a search match notification during the data reading from the cache control unit. It is determined whether the next command is an instruction to write or read data to the magnetic disk device, and if it is a data read instruction, the execution start of the next command is waited in the magnetic disk controller. Aside
When the cache control device finishes the track data read operation, the next command is executed. On the other hand, in the case of a data write instruction, send a write command execution instruction. In response to a write command execution instruction from the command check unit, a write command execution unit that reads the data to be written to the magnetic disk device from the central processing unit and transfers it to the cache control device, and data between the write command execution unit and the central processing unit. 2. The magnetic disk controller according to claim 1, further comprising: a system interface unit for delivering and receiving data, and a device interface unit for delivering and receiving data between the write command execution unit and the cache controller. Magnetic disk subsystem.