JPH07152677A - Data transfer control method - Google Patents

Abstract

PURPOSE:To prevent deterioration in performance of a communication cable due to the transfer delay time by setting intervals of data requests on the b ' data transfer speed between a storage control part and an information storage part when the data requests are issued. CONSTITUTION:The storage control part 3 and information storage part 4 which are connected to a host processor 1 constitute an information storage subsystem 2. The storage control part 3 receives a data transfer start indication 11 and transmits a 2nd data request 13 even between the end of the transmission of a 1st data request 12 and the reception of 1st data, so a buffer 6 never becomes empty. Then intervals 17 between respective 2nd data requests 13 are calculated on the basis of the mean transfer speed of data from the storage control part 3 to the information storage part 4. Consequently, the data mean transfer speed between the storage control part 3 and host processor 1 never exceeds the data mean transfer speed between the storage control part 3 and information storage part 4, so the buffer 6 never overflows.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information storage subsystem having a storage control unit and an information storage unit connected to a host processing device, and more particularly, to a data storage process when data is written from the host processing device to the information storage unit. The present invention relates to a data transfer control method for a control unit to control transmission of a data request to a host processing device.

[0002]

2. Description of the Related Art A storage control unit to which interfaces having different transfer rates are connected to a higher-level processing unit and an information storage unit stores a data temporarily in order to adjust the difference in the transfer rate. Buffer) is required. For example, when the host processor executes data writing to the information storage unit, the host processor sends a write data transfer start instruction to the storage controller. Upon receiving this instruction, the storage control unit transfers the data request to the host processing device. The data transferred from the host processor differs in the transfer speed and the storage speed at which the information storage unit stores data, so it is temporarily stored in a buffer to adjust the speed difference, and then transferred to the information storage unit. It

JP-A-1-233646 discloses that in such an information storage subsystem, when the storage control unit makes a data request to a higher-order processing device, the amount of data requested at one time does not exceed the buffer capacity. There is disclosed a data transfer control method of waiting for data transfer from the buffer to the information storage unit when the buffer capacity is insufficient and securing the buffer capacity before making a data request.

[0004]

In recent years, from the viewpoint of improving the degree of freedom in the arrangement of the apparatus, it has been required to extend the cable distance between the host processing apparatus and the recording control section. However, if the communication cable connecting the host processor and the storage controller becomes long, the time (transfer delay time) from when the data request is sent to the host processor until the data corresponding to the data request arrives is full. The state buffer read time may be exceeded. In this case, in the conventional method, the data transfer from the buffer to the information storage unit is completed before the requested data is received, and the buffer becomes empty. Therefore, from the end of the data transfer from the buffer to the information storage unit until the data newly transferred from the host processor to the storage control unit is transferred from the buffer to the information storage unit, There was a problem that the data transfer to the server stopped and the performance deteriorated.

FIG. 3 schematically shows the exchange of a series of signals between the above-mentioned storage control unit and the upper processing unit. 21
Is a data transfer start instruction, 22 is a data request, and 23 is data to be transferred. Upon receiving the data transfer start instruction 21, the storage control unit first continuously transmits a data request having a capacity corresponding to the buffer capacity. After that, when the free area of the buffer becomes equal to or larger than the capacity required by the data request 22, the storage control unit transfers the data request to the upper processing device. As shown in FIG. 3, according to this method, data transfer between the storage control unit and the information storage unit is stopped.

An object of the present invention is to transfer a communication cable in an information storage subsystem even when the transfer delay time of the communication cable connecting the host processor and the storage control unit exceeds the read time of a buffer in a full state. An object of the present invention is to provide a data transfer control method in which the performance is not deteriorated by the delay time.

[0007]

[Means for Solving the Problem] The buffer becomes empty because the data processing device prevents the buffer overflow (the pointer on the input side overtakes the pointer on the output side) by the buffer capacity of the upper processing device. The cause is that no data request is made over the range.

In order to solve this problem, according to the present invention, the storage control unit receives a data transfer start instruction and transmits a data request of a capacity corresponding to the buffer capacity until the first data is received. Data requests are sent continuously without allocating an open area in the buffer. Further, in order to prevent the buffer overflow, the interval between each data request is determined from the information transfer rate between the storage control unit and the information storage unit.

FIG. 1 shows a basic configuration diagram of the present invention. The storage control unit 3 and the information storage unit 4 connected to the higher-level processing device 1 constitute an information storage subsystem 2. The storage control unit 3 has a buffer 6 and a buffer control means 7, and the upper processing device 1
Interface cable 5 for connecting the storage controller 3 to the storage controller 3
The transmission delay time is longer than the maximum read time of the full buffer.

FIG. 2 schematically shows a series of exchanges of signals between the storage controller 3 and the host processor 1 according to the present invention. Reference numeral 11 is a data transfer start instruction, 12 is a first data request having a capacity corresponding to the buffer capacity, 13 is a second data request transmitted before receiving the first data, 1
4 is a third data request transmitted after receiving the first data, and 15 is data to be transferred.

When the storage control unit 3 receives the data transfer start instruction 11, it issues a first data request 12 for a capacity corresponding to the buffer capacity.

Further, the storage control unit 3 transmits the second data request 13 before the arrival of the first data 15 transmitted from the host processing device 1 in response to the first data request 12. The interval 17 between the respective second data requests 13 is determined by the average data transfer rate between the buffer 6 and the information storage unit 4, and the data of the capacity required by one data request is transferred from the buffer to the information storage unit. It is calculated from time 16 transferred to.

After the arrival of the first data transmitted from the upper processing unit 1, the storage control unit 3 makes the third data request 14
To send. The third data request 14 is transmitted after securing an area for storing the requested amount of data in the buffer 6.

[0014]

In the present invention, the storage control unit 3 receives the data transfer start instruction 11, and the storage control unit 3 receives the first data request 12
Since the second data request 13 is transmitted during the period from the end of the transmission to the reception of the first data, the buffer 5
Will never be empty. Also, each second data request 13
By calculating the interval 17 between them based on the average transfer rate of data from the storage control section 3 to the information storage section 4, the average data transfer rate between the storage control section 3 and the higher-level processing device 1 becomes Since the average data transfer rate between the storage control unit 3 and the information storage unit 4 is not exceeded, overflow of the buffer does not occur. Therefore, in an information storage subsystem to which an interface is connected whose transfer delay time exceeds the read time of a buffer in a full state, it is possible to efficiently use the buffer of the storage control unit and prevent performance deterioration due to the transfer delay time. it can.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 4 shows a block diagram of a disk device subsystem which is an embodiment of the present invention. 4, the disk controller 33 communicates with both the optical communication controller 34 that controls the communication protocol with the upper optical channel 31, the external storage controller 40 that controls the lower disk device 42, and both. It comprises a channel control unit 38. Each control unit is connected by an optical fiber cable 32, an optical communication control unit / channel control unit path 37, a channel control unit / external storage device control unit path 39, and an external storage device control unit / disk device path 41. To be done. 1 corresponds to the optical channel 31, the storage controller 3 corresponds to the disk controller 33, and the buffer 6 corresponds to the buffer 35 provided in the optical communication controller 34 inside the disk controller 33. The information storage unit 4 corresponds to the disk device 42.

Optical communication control section 34 having a buffer 35
Write data from the optical channel 31 or read data from the disk device 41 to the buffer 35.
Data is transferred after it is loaded into. The data fetched in the buffer 35 is processed by the buffer control unit 32 of hardware control in the order of fetching.
8 or to the upper optical channel 31. further,
The buffer control unit 36 reads a program stored in a storage unit (not shown) and controls write data transfer by this program.

FIG. 5 shows an outline flow of write data transfer control of the optical communication controller in the embodiment of the present invention. Figure 6
FIG. 4 shows a detailed flow of write data transfer control of the optical communication control unit in the embodiment of the present invention.

A simple control flow will be described below with reference to the flowchart of FIG. First, the write data transfer is started by transmitting a data transfer start instruction by the optical channel 31 (step 100). Write data transfer control
Data transfer control below buffer capacity (step 10
1), data transfer control before data arrival (step 10
2) and data transfer control after receiving data (step 1
03) is executed in this order. After the optical communication control unit transfers all the data designated by the data transfer start instruction to the channel control unit, the optical communication control unit sends a write data transfer end report to the optical channel and ends the process (step 104).

In the data transfer control below the buffer capacity (step 101), the optical communication control unit 34 causes the optical channel 3 to operate.
Data is continuously requested to 1 within a range not exceeding the buffer capacity.

In the data transfer control (step 102) before the arrival of data, the data request to the optical channel 31 is made at a predetermined time interval. This time interval is required to transmit the data transmitted from the optical channel 31 from the buffer 35 to the channel control unit 38 by one data request, which is obtained from the average data transfer rate from the buffer 35 to the channel control unit 38. Calculated from time.

The data transfer control (step 103) after the arrival of data is carried out by monitoring the data transfer from the buffer 35 to the channel controller 38 after the data request is transferred to the optical channel 31 and transferring the data by the data transfer. When the data capacity exceeds the data capacity transmitted from the optical channel 31 by one data request, the data request is made to the optical channel 31.

Next, the detailed control flow of the write data transfer of the optical communication control section 34 will be described with reference to the flowchart of FIG. 6 and the time chart of FIG. Number of remaining write data A
Is a variable indicating the number of data obtained by subtracting the number of requested data from the total number of write data specified by the write data transfer start instruction from the optical channel 31. The remaining buffer capacity B is a variable indicating the capacity of the buffer 35 that is not used for storing data. In this embodiment, data transfer is performed in packet units including control information such as a data transfer start instruction and data request. The packet capacity P indicates the maximum number of data that can be stored in a packet.
Next, the data number sweep timer value AT is stored in the buffer 35
From the last data request based on the average data transfer rate from the channel controller 38 to the channel controller 38, data corresponding to the value A is stored in the buffer 3
The timer value swept from 5 is shown. Finally, as for the data number sweeping timer value PT, data of P value is swept from the buffer 35 from the last data request based on the average data transfer rate from the buffer 35 to the channel controller 38 by the buffer controller 36. Indicates the timer value.

First, the write data transfer start instruction 31 is transmitted from the optical channel 31 (step 200), and the total write data number is designated. Next, the initial value of the A value is the total number of write data, the initial value of the B value is the capacity of the buffer 35, and the P value is the packet capacity (step 201).

When the number of remaining write data is not larger than the buffer capacity (A ≦ B) (step 202), while the A value is larger than the P value (A value ≧ P value) (step 207), the optical channel 31 is set in packet capacity units. The first data request 12 is made to the (step 208), and the P value is subtracted from the A value (A = AP) in order to monitor the number of remaining write data (step A209). If the A value becomes less than or equal to the P value (step 20
7), the first data request 12 for the A value is sent to the optical channel 31
(Step 210) and the process proceeds to Step 407.

The number of remaining write data is more than the buffer capacity (A
> B) (step 202), the first data request 12 is first sent to the optical channel 3 within a range not exceeding the buffer capacity.
Send to 1. Therefore, a data request is transmitted to the optical channel 31 in units of packet capacity (P value) (step 203), and the P value is subtracted from the B value and the A value in order to monitor the number of remaining write data and the remaining buffer capacity. (B
= B-P, A = A-P) (steps 204, 205),
While the B value is the P value or more (B> P) (step 206), steps 203 to 206 are repeated. B value is P value or more (B
> P), the process proceeds to step 301.

Next, the control before data reception, which is the point of the present invention, will be described. First, the timer values of AT and PT that specify the data request interval are set (step 3).
01). If the A value is less than or equal to the P value (step 30
2) A second data request 13 corresponding to the A value is transmitted to the optical channel 31 at an interval of the sweep time AT value corresponding to the A value from the transmission of the last data request (steps 308 and 309) (step 308). 310), and proceeds to step 407. Further, when the A value is equal to or larger than the P value (A ≧ P) (step 30
2) Determine whether or not the requested data has arrived (step 30
3) It is determined whether or not the data sweep time for the P value has elapsed from the last data request. Here, in monitoring the data sweep time for the P value, it is determined whether or not PT = 0 (step 304), and if PT = 0, the timer value is subtracted from the PT value (step 305). In the processing of steps 303 to 305, whether data arrives or PT =
Repeat until it reaches 0. When the data arrives, the process proceeds to step 401. When the data sweep-out time for the P value has elapsed from the last data request before the data arrival (PT = 0), the second data request 13 for the P value is transmitted to the optical channel 31 (step 306). ), In order to monitor the number of remaining write data, the P value is subtracted from the A value (step 307) and the process returns to step 301. next,
If the number of remaining write data becomes smaller than the packet capacity before the data is received (step 302), the sweep time AT value for A value from the last data request is monitored (step 3).
08), the second data request 13 for the A value is transmitted to the optical channel 31 (step 310), and step 407.
Move to.

Finally, the control after the arrival of data will be described.
For the data request after the data arrival, the method of controlling the interval between the data requests by the sweep time for one packet before the data arrival, to the method of monitoring the completion of the transfer of the data of one packet to the channel controller. Switch. First,
The data received in the buffer 35 is transferred to the buffer control unit 22.
Are transferred to the channel control unit 38 by. Step 4
In 01, after transmitting the last data request, the buffer control unit 22 monitors the data transmission to the channel control unit 38, and the buffer control unit 22 completes the transfer of the data for the P value to the channel control unit 38. When the optical channel 31
In response, the third data request 14 for the P value is transmitted (step 402), and the P value is subtracted from the A value (step 40).
3), while the A value is greater than or equal to the P value (A ≧ P), step 401
-403 is repeated. When the A value becomes equal to or less than the P value, after the last data request is transmitted, the buffer control unit 36 monitors the data transmission to the channel control unit 38, and the buffer control unit 36 notifies the channel control unit 38 of the A value. When the transfer of the minute data is completed, the third data request 14 for the A value is transmitted to the optical channel 31 (step 40).
6) and moves to step 407.

Finally, the buffer controller 36 monitors the data transmission to the channel controller 38 (step 40
7) When all the write data can be transmitted to the channel controller 38, a write data transfer completion report is transmitted and the process is terminated (step 408). Steps 407-408
Is executed to increase the reliability of data transfer.

In this embodiment, the data request is made on a packet-by-packet basis, but it is also possible to request the data of a plurality of packets by a single data request.

[0030]

Since the data is transferred from the host processor to the storage controller regardless of the transfer delay time of the cable, the buffer will not become empty due to the transfer delay time. Therefore, in the data transfer between the storage control unit and the information storage unit, the transfer waiting time to the lower storage device is eliminated, so that the efficient data transfer can be realized and the deterioration of the performance due to the transfer delay time of the cable can be prevented. .

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of the present invention.

FIG. 2 is a time chart schematically showing the exchange of signals between the storage control unit and the host processing device according to the present invention.

FIG. 3 is a time chart schematically showing the exchange of signals between a storage control unit and a higher-level processing device in the prior art.

FIG. 4 is a hardware configuration diagram of a disk subsystem including an optical communication control unit according to an embodiment of the present invention.

FIG. 5 is a schematic flowchart of microprogram control of the optical communication control unit in the embodiment of the present invention.

FIG. 6 is a detailed flowchart of microprogram control of the optical communication control unit in the embodiment of the present invention.

[Explanation of symbols]

1: Host processor 11: Data transfer start instruction 2: Information storage subsystem 12: Data request below buffer capacity 3: Storage control unit 13: Data request before first data arrival 4: Information storage unit 14: First data Data request after incoming 5: Interface cable 16: Data transfer time for P value 6: Buffer 7: Buffer controller

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Satoshi Kodama Satoshi Kodama 2880 Kozu, Odawara City, Kanagawa Stock Company Hitachi Storage Systems Division (72) Inventor Mikihito 2880 Kozu, Odawara City, Kanagawa Hitachi Ltd. In storage system division (72) Inventor Shigeru Kaga 1 Horiyamashita, Hadano-shi, Kanagawa Hitachi Computer Engineering Co., Ltd. (72) Inventor Shinjiro Shiraki 2880, Kozu, Odawara, Kanagawa Hitachi Computer Equipment Co., Ltd.

Claims (4)

[Claims] 1. A high-order processing apparatus, a storage control section having a storage means for temporarily holding data transferred from the high-order processing apparatus, a connection between the high-order processing apparatus and the storage control section, and a transmission line. Is a data transfer control method for a data processing system having an interface, the transfer delay time of which is longer than the maximum read time of the storage means, and an information storage section connected to the storage control section, wherein the storage control section performs the higher-level processing. When issuing a data request to a device, a data transfer interval is set based on a data transfer rate between the storage control unit and the information storage unit. 2. A high-order processing apparatus, a storage control section having a storage means for temporarily holding data transferred from the high-order processing apparatus, a connection between the high-order processing apparatus and the storage control section, and a transmission line. Is a data transfer control method for a data processing system having an interface, the transfer delay time of which is longer than the maximum read time of the storage means, and an information storage section connected to the storage control section, wherein When issuing a data request to the device, the storage control unit issues a first data request corresponding to the capacity of the storage means and then receives the first data transferred from the host processing device. In the data transfer control method, the storage controller issues a second data request to the higher-level processing device. 3. The interval for issuing the second data request is
The data transfer control method according to claim 2, wherein the setting is performed based on a data transfer rate between the storage control unit and the information storage unit. 4. The interval for issuing the second data request is
3. The data transfer control method according to claim 2, wherein the storage control unit is substantially equal to the time required to transfer the data of the capacity requested by the data request to the information storage unit.