JPH02226355A - Load balance control method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control method for balancing the load on a data transfer path between a group of input/output devices and a group of control devices.

[Conventional technology]

Conventionally, as a method of balancing the load among multiple data processing devices or pig transfer paths, for example, Japanese Patent Laid-Open No. 57
There is a method described in Japanese Patent No.-157368. When allocating work to parallel data transfer paths, each processing delay is counted, and if the total value of one transfer path exceeds the threshold, a part of the work allocated to that data transfer path is transferred to another transfer path. By shifting the load to the road, the load is balanced. In the specific example of the method described in the above publication, two cartridge-type MTs (magnetic tape devices) each have two
It is connected to the other controller via a data transfer path.

However, during the time when one MT is transferring data with the control device, other MTs cannot transfer data with this control device. The control device executes pre-reading and collective writing of a plurality of blocks between each buffer and MT.

In this case, the data of one MT is controlled by one specific control device and is stored only in the buffer within this control device, to avoid distributing the data of one MT to the buffers of multiple control devices. transfer between. When one MT among a set of MTs controlled by a specific control device is in a transfer operation between a channel and a buffer, other MTs in this set are in a transfer operation between this channel and a buffer. It is not possible. Similarly, if one MT in the set moves to a data transfer operation between buffers, no other MT in the set can move to a transfer operation with the buffer. Therefore, load imbalance occurs within the set of MTs controlled by each control device, resulting in empty data transfer paths and deterioration of performance. For this purpose, the load on each control device is balanced by appropriately transferring the set of MTs under the control of each control device.

In addition, compression and decompression functions have been added to the MT control device,
There are cases where the device connects to a channel faster than the main unit and transfers data. This apparently reduces the amount of data transferred between the control device and the MT. It is common practice to obtain faster channel throughput. multiple MTs
When the MT is in operation, the data compression rate of each MT is usually different. In that case, if MTs with high compression ratios are concentrated in the set controlled by one controller, and MTs with low compression ratios are concentrated in the set controlled by the other controller, the former controller controls the channel. Although sufficient performance can be obtained for throughputs up to 1, the latter control device cannot obtain performance up to channels. Therefore, even in such a case, by transferring the set of MTs controlled by both control devices, the compression ratio of the set of MTs controlled by both control devices can be balanced, and the performance of both control devices can be channelized. The throughput can be improved up to .

The method described in the above-mentioned publication describes a method for selecting MTs to be subjected to MT transfer.

That is, when receiving an input/output request for a certain MT from a channel, the number of times that other MTs under the control of the same control device were unable to immediately start a transfer operation due to data transfer or the like is counted.

Then, this number of times is totaled for each set under the control of each control device. When the difference between the total values for each set exceeds a certain value (threshold value), it is determined that the loads between the control devices are not balanced, and the MT is transferred.

In this case, the MT to be transferred is selected to be one that is close to half of the difference in the total number of times the transfer could not be performed, that is, the total value for each control device.

[Problem to be solved by the invention]

In the method described in Publication No. 2, as mentioned above, each M
The difference between the summed values for each set of MTs controlled by the same control device is counted for the number of times T could not immediately start a transfer operation because another MT was in the process of transferring. Then, the MT whose number of times it could not immediately move to data transfer is close to half of this difference is targeted for transfer.

In this case, it is clear that the control device that has a larger total number of times that it was unable to immediately start data transfer has a higher load. However, even if you transfer MTs that are close to half of the difference in total value from the high load side to the low load side, the throughput will not improve to the maximum, and both loads will not completely increase. It is rarely balanced, and the basis for this is extremely weak.

Normally, it is more important to maximize the total value of the throughput, utilization rate, etc. of both control devices than to balance the input/output waiting times, etc. of both control devices.

Furthermore, if there are multiple access routes to the control device for each MT, there is no guarantee that these access routes will be used equally. Generally, different access paths cause different internal processing overheads within the control device.

In the method described in the above publication, even if the MT is transferred,
The internal processing overhead of different control devices is not reduced depending on the access path, and no consideration is given to this point.

The purpose of the present invention is to solve such conventional problems, to relocate the MT that maximizes the throughput or utilization rate of both control devices, and to replace the MT when the total throughput does not improve. An object of the present invention is to provide a load balancing control method that targets MTs for relocation so as to balance output waiting times.

Another object of the present invention is to provide a load balancing control method that can select an MT that balances the loads of each control device.

Still another object of the present invention is to provide a load balancing control method that can reduce the internal processing overhead of the input/output system while balancing the load.

[Means to solve the problem]

In order to achieve the above object, the load balancing control method of the present invention includes a plurality of control devices connected to each of the plurality of channels, and a group of input/output devices connected to each of the control devices,
In a computer system in which each input/output device is under the control of one control device at the same time, and data is transferred only between the control device being controlled, the input/output device under the control of one control device can be transferred to another control device. When transferring the input/output devices under the control of each control device after transfer, use an analytical model to perform predictive calculations on the input/output load status of a set of input/output devices that will be under the control of each control device after the transfer, and perform the predictive calculations. Before executing, the information necessary for the prediction calculation is collected, and as a result of the prediction calculation, the transfer method that will improve the performance of each control device the most is selected, and if the transfer does not improve the performance, The method is characterized in that it then selects the relocation method that will best balance the input/output load amount, and then relocates the set of input/output devices under the control of each control device according to the result of the selection. be.

It also includes a plurality of control devices connected to each of the plurality of channels and a group of input/output devices connected to each of the control devices, and each input/output device is under the control of one control device at the same time. , it has been M#! In a computer system that transfers data only to and from a control device, selection of the input/output device to be transferred by the control device when transferring an input/output device under the control of one control device to the control of another control device. In addition to determining the selection order, before making the determination, information including the routes accessed from the higher-level system for each control device at a predetermined time necessary for determining the selection order is collected, and the input/output load is balanced. Another feature is that the selection order is determined so that the set of input/output devices under control is transferred between each control device.

[For production]

In the present invention, the first embodiment consists of two operations: (a) data collection for predictive calculation, and (b) predictive calculation of the load status after transfer, and the second example consists of (a) data collection for predictive calculation; ) Collection of data for input/output device selection order and load balancing, and (
b) Consists of two operations: relocation of input/output devices. That is, in the first embodiment, the output, utilization rate, input/output waiting time, etc. of the data transfer path are predicted by calculation using an analytical model. As a result, the throughput, utilization rate, and I
The zero response time is calculated for each case when each MT is targeted for relocation, and the MT whose throughput and utilization rate of the surface control device are most improved by relocation is determined as the target for relocation.

Furthermore, if the throughput and utilization rate do not improve, the MT with the most balanced load is targeted for transfer.

Furthermore, in the second embodiment, by reducing communications between control devices when executing input/output commands, internal overhead of the input/output system, which varies depending on the access path, is reliably reduced. That is, when transferring input/output loads so that the input/output loads are balanced, the input/output devices to be transferred are selected so as to reduce communication between control devices when executing input/output commands.

As a result, high performance can be achieved by appropriately selecting a set of input/output devices under the control of each control device and balancing the input/output loads on each control device.

Further, it is possible to reduce the internal processing overhead of the input/output system while balancing the input/output load on each control device.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a configuration diagram of a computer system to which the present invention is applied.

The computer system in Figure 2 consists of a CPU 20 and this CPU 2.
0, two control devices A23°B24 connected to these channels A21 and B22, respectively, and these surface control devices A23. It is composed of a plurality of cartridge type MT25s commonly connected to the B24. In this embodiment, the human output device will be explained as a cartridge type MT, but it goes without saying that the present invention can also be applied to a general input/output device.

Car 1~ridge type MT25 is plane control device 1A23°B
24, it is possible to perform data transfer with either device. However, since each MT of the cartridge type MT 25 is under the control of either the control device A 23 or the control device B 24, data transfer is actually performed only with the control device that is being controlled. It turns out.

FIG. 3 is a detailed block diagram of the control device in FIG. 2.

Since the control devices A23 and 824 have the same configuration, only the control device A23 will be described.

The processor A300 controls data transfer of the cartridge type MT25 under the control of the control device A23. When the pre-read/collective write data of the cartridge type MT25 controlled by the control bag @A23 is transferred, these data are stored in the buffer A3O2. Processor A3
00 is a prediction information collection function (program) A313, a prediction calculation execution function (program) A315, a control device table A308, and a cartridge type MT table A31.
Although not shown in the figure, other well-known functions are also built in. Processor A300 is
Execute the prediction information collection function A313 and select cartridge type M.
After collecting the information necessary for transferring the T25, the predictive calculation execution function A315 is executed, and the predictive calculation execution function A315 determines a method for transferring the cartridge type MT25 while communicating with the processor B501.

The data transfer device CA304 with a compression/decompression circuit transfers the channel A21 or B22 and the buffer A302 with respect to the cartridge type MT25 under the control of the control device A23.
Data transfer between the computer and the computer is performed by performing compression/decompression processing. That is, data is received from channel A21 or B22, compressed, and then transferred to buffer A.
302, and transfer data in the opposite direction.]7 When performing data transfer, perform restoration processing and then transfer data to channel A.
21 or B22. In this case, the data transfer device CA304 with a compression/decompression circuit has a function of measuring the amount of data transferred in a compressed state. On the other hand, the data transfer device DA306 performs data transfer processing between the cartridge type MT25 controlled by the control device A23 and the buffer A302. The control device table A308 built into the processor A300 is a table that stores information for each control device, and is a table that stores information for each control device.
Reference numeral 310 is a table that stores information for each cartridge type MT 25. Information about each cartridge type MT 25 will be stored in a table within the control device being controlled at that time.

A control information path 312 connecting processors A300 and B501 is for exchanging control information between both processors.

The operation of the apparatus of FIG. 3 is as follows.

When the processor A300 receives an input/output request from the channel A21, it first checks whether the input/output request is a request for the ridge type MT25 of the car 1 controlled by the controller A23. Next, if the request is for the cartridge-type MT25 under control, it is checked whether the data transfer device CA304 with compression/decompression circuit is transferring data with the channel B22. If data is being transferred, it is not possible to proceed to data transfer processing for the received input/output request until this transfer is completed.

Also, even when data is not being transferred, buffer A
Even if you want to read data from the buffer A 302, there may be no data, and even if you want to write data to the buffer A 302, there may be no free space, so in such cases it is not possible to immediately proceed to data transfer. Therefore, it is possible to proceed to the data transfer operation only when the above-mentioned state is not present.

Note that if it is not possible to move on to data transfer, the connection state with channel A21 will be temporarily released and a waiting state will be entered. Further, if the input/output request received from the channel Δ21 is a request for the cartridge type MT 25 controlled by the control device B24, this request is transmitted to the processor B501 via the control information path 312.

On the other hand, when an input/output request is issued to the cartridge type MT 25 controlled by the control device A23 through the channel B22, the control device B24 first receives this input/output request and is under the control of the other party's control device A23. This request is communicated to processor A300 in controller A23 through control information path 312. When processor A300 receives this request, it determines whether to move on to data transfer processing for this input/output request or to wait, as described above.

If only such control is performed, and the loads of the cartridge type MT25s controlled by each control device are not balanced, only the set of cartridge type MT25s controlled by one control device will be affected. This results in a lot of waiting for data transfer. Furthermore, if the compression ratio of only the set of cartridge-type MTs 25 controlled by one control device is low, the maximum transfer capacity of the channel cannot be brought out.

Therefore, the load is balanced between the control device A23 and the control device B24 by appropriately transferring the sets of cartridge-type MTs 25 under their respective control.

In this embodiment, first, a method of transferring MTs that satisfies condition 1 is selected, and if there is no method of transferring MTs that satisfies condition 1, then a method of transferring MTs that satisfies condition 2 is selected.

Condition 1 → total value of throughput of control devices A23 and 324, or data transfer device CA with compression/decompression circuit,
The total value of data transfer utilization rate etc. of 304 and CB505 is
Transfer MT that can be improved from the current value.

If there are multiple ways to improve the transfer,
Select the one with the greatest improvement rate.

Condition 2 -> M and T are changed so as to best balance the average data transfer response time or average data transfer waiting time for the control devices A23 and B24.

Here, the case where the total value of the data transfer utilization rate of the pig transfer apparatus CA30/3 with a compression/decompression circuit and the CB505 is maximized as condition 1, and the case where the data transfer waiting time is made equal as condition 2 will be described.

First, the average data transfer waiting time of a set of cartridge-type MTs 25 controlled by the control device A 23 and the average data transfer waiting time of a set of cartridge-type MTs 25 controlled by the control device B 24 are measured.
Utilization rate of data transfer path of data transfer device CA304 with decompression circuit and data transfer device CB5 with compression/decompression circuit
The utilization rate of the data transfer path of 05 is measured. As a result of this measurement, if there is a difference in the average data transfer waiting time, or if one of the data transfer devices is experiencing a bottleneck, the cartridge type MT22 under each control will be An appropriate set of MTs is selected from the set of MTs, and the transfer process is executed. In this case, the most important issue is which MT should be transferred to satisfy the above conditions. Therefore, in this embodiment, the average data transfer waiting time and the utilization rate of the data transfer path of the set of cartridge type MTs 25 under the control of each control device after the transfer is predicted.

Conventionally, several methods have been used as analytical models for predicting average data transfer waiting time and transfer path utilization rate. In this embodiment, by measuring the information necessary for predicting the transfer path utilization rate and data transfer waiting time while each cartridge type MT25 is in operation, each control unit between the surface control devices A23 and 824 is Car 1-ridge type 1. The average data transfer waiting time of the set of car 1 heritage type MT25 under each control when the A T 25 transfer is executed and the utilization rate of the data transfer path are predicted and calculated. The transfer method is selected according to the results of this predictive calculation, the conditions] and the contents of condition 2.

When measuring information to predict utilization rates and average waiting times, the information differs depending on each analysis model.

Since the cartridge type M, T25 is normally occupied by one program, it is desirable to use an analytical model in which the number of processing requests in the model is equal to the number of MTs in operation, and therefore a constant number. Examples of such analysis models include the asymptotic approximation method and the machine repairman model. Information to be measured when using these models includes the number of operating cartridge-type MT25s, the average time interval between the end time and arrival time of input/output requests for each cartridge-type MT25, the average pig transfer time, and the compression ratio. be. In this embodiment, by measuring these six pieces of information, it is possible to predict and calculate average waiting time, average response time, throughput, and utilization rate.

Here, as described above, the case where the average waiting time and utilization rate are balanced will be described in detail.

For example, when the asymptotic approximation method is applied, the average waiting time can be obtained from the following equation.

(Average waiting time) = (Number of MTs - 1) x (Average data transfer time) XMAX (1, (MT data transfer speed)
/(Channel data transfer rate)/(Compression ratio)) = (Average time interval between input/output request end time and arrival time)...
(1) Here, regarding the control device A23, the average waiting time is the buffer 3 of the control device A23.
02 and channel A21, and the average data transfer time is also the data transfer time between the above devices,
The number of MTs is Kerr I Ridge type MT25 under the control of A23.
The average time interval is the time interval until the next request. Further, MAX (a, b) is a function that takes the larger value of a and b.

If the above equation (1) takes a negative value, the average waiting time is O
Make it. Note that the data transfer rate of the MT and the data transfer rate of the channel are usually well known, so there is no need to specifically measure them.

Next, the utilization rate is expressed by the following formula.

(Utilization rate) = (Number of MTs) x (Average data transfer time)
XMAX (1, (MT data transfer rate) / (channel data transfer rate) / (compression ratio)) / (average data transfer time 10 people Average time interval between end time and arrival time of output requests)... ... (2) Since the above equation (2) is the utilization rate, when the value exceeds 1, the utilization rate is set as 1.

After all, when using the asymptotic approximation method, the number of cartridge-type MT25s under each control is clear, so
By measuring the average data transfer time of each car 1 to cartridge type MT25, the average time interval between the end time and arrival time of input/output requests, and the compression ratio, we can transfer the cartridge type MT25 to the controller on the opposite side. It is possible to predict and calculate the average data transfer waiting time and utilization rate of the cartridge type MT 25 under the control of each control device when the control is transferred.

FIG. 4 is a diagram showing information on the control device of the cartridge type MT, and FIG. 8 is a diagram showing the format of the control device table in FIG. 3.

Here, predictions are made by predicting the number of cartridge-type MT25s, data transfer time, and the average time interval between the end time and arrival time of people's requests, using an asymptotic approximation method or a machine repairman model. The flow of processing will be described in detail, taking as an example the case where an analytical model that can be calculated is used.

FIG. 8 shows the format of the control device table A308 and the control device table B509 shown in FIG. 3. These tables store respective values for the same items, including the number of MTs 80, channel transfer rate 81, and MT transfer rate 82. Among these, the number of MTs 80 is the number of Carmy Ridge type MTs 25 currently in operation and under the control of the self-control device. Further, the channel speed 81 is the data transfer speed of channels A21 and 822, and the MT transfer speed 82 is the data transfer speed of each cartridge type MT 25.

FIG. 4 shows the formats of the cartridge type MT table A310 and the cartridge type MT table B511 shown in FIG. 3. These information is a car with these information! - Stored in the control device that controls the ridge type MT25. First input/output end time 4
0 stores the time when data transfer of the previous input/output process ended.

The next data transfer start time 41 stores the time when data transfer is started. The data transfer wait occurrence bit 42 indicates that when an input/output request for a certain cartridge type MT25 is received, for example, the control device controlling this MT is in the process of transferring data to another cartridge type MT25, or there is no pre-read data. If data transfer cannot be started immediately for some reason, this bit is turned ON.

The next data transfer wait start time 43 stores the time when the bit 42 is turned ON. Further, the number of input/output requests 44 is the total value of the number of input/output requests issued to the car 1 to the cartridge type MT 25 after the selection and calculation of the cartridge type MT 25 to be transferred last time. The cumulative data transfer waiting time 45, the cumulative data transfer time 46, and the cumulative input/output issuing time interval 47 are the data transfer waiting time and data of the cartridge type MT25 after the previous selection and calculation of the cartridge type MT25 to be transferred, respectively. This is the cumulative value of the time interval between transfer time, input/output end time, and arrival time. The cumulative compressed data transfer amount 48 and the cumulative uncompressed data transfer amount 49 are the data transfer amount in the compressed state,
The compression rate can be obtained from the cumulative compressed data transfer amount 48 and the cumulative uncompressed data transfer amount 49, which is the amount of data transferred in an uncompressed state.

Figure 5 shows the processing flow 1 when the number of input/output requests is taken.
FIG. 6 is a processing flowchart 1 when data transfer is started, and FIG. 7 is a processing flowchart when data transfer is finished. In these processes, data is collected by the prediction information collection functions A313 and B514 in FIG.

In FIG. 5, first, from the current time, the input/output end time 40 of the car 1 heritage type MT25 to which the input/output request is issued is shown.
After subtracting and obtaining the current I/O request issuing time interval,
This is added to the cumulative input/output issue time interval 47 of this MT (step 500).

Next, the number of input/output requests 44 is increased by 1 (step 5
01). Next, it is checked whether data transfer can be started immediately in response to this input/output request (step 502).
6. If the transfer can be started immediately, the process ends without any special processing. If the transfer cannot be started immediately, the data transfer wait generation bit 42 is turned on and the data transfer wait start time 43 is set to the current time (step 503).
.

In FIG. 6, when starting data transfer, it is checked whether the data transfer wait occurrence bit 42 is turned on (step 600).

If it is not ON, it means that the data can be transferred immediately, so the current time is set to the data transfer start time 41 (step 603). If it is ON, the data transfer wait start time 43 is subtracted from the current time to obtain the input/output request issuance interval time, which is then added to the cumulative input/output issuance interval time 47 (step 601). . Next, the data transfer wait generation bit 42 is turned off (step 602).

Then, store the current time in the data transfer start time 41,
The process ends (step 603).

In FIG. 7, at the end of data transfer, the data transfer start time 41 is subtracted from the current time of the cartridge type MT 25 that has finished data transfer to obtain the current data transfer time, and this is calculated as the cumulative data transfer time of this MT. Add to time 46 (step 700). Next, the current time is set to the input/output processing end time 40 (step 701). moreover,
Data transfer circuit with compression/decompression circuit CA304. CB5
The compressed data transfer amount and the uncompressed data transfer amount are extracted from 05 and added to the cumulative compressed data transfer amount 48 and cumulative uncompressed data transfer amount 49, respectively (step 702).

FIG. 1 is a flowchart of MT relocation processing showing one embodiment of the present invention.

This is the main process of the present invention, and is a process for selecting an MT to be transferred by the predictive calculation execution function A315, 8316 in order to balance the load. The controller A2 selects the cartridge type MT25 to be transferred.
3. It can be executed on either side of B24. It may be performed alternately depending on load balance, etc., but there is no particular limitation on this. However, all of the information shown in FIGS. 4 and 8 needs to be collected in the control device that selects the cartridge type MT 25 to be transferred.

The process shown in FIG. 1 is executed after a predetermined period of time has elapsed. First, a request is issued from the other party's control device to send information necessary for selecting a method of transferring the cartridge type MT 25 (step 100). Next, it waits for this information to be sent from the other party's control device (step 101). The information sent from the other party is that the number of MTs is 80, and each cartridge type MT25.
number of input/output requests 44, cumulative data transfer waiting time 45, cumulative data transfer time 46, cumulative input/output issue time interval 47,
Cumulative compressed data transfer amount: 48, Cumulative uncompressed data transfer amount: 4
There are 7 of 9. First, it is checked whether or not the cartridge type MT 25 under the control of both control devices is to be transferred (step 102). To do this, the utilization rate of the data transfer path is obtained according to equation (2) for calculating the utilization rate described above. As a result, if the utilization rate of either device is smaller than 1 by a certain value, it is determined that there is a possibility of improving the utilization rate, and the process branches to step 104, where a transfer is performed to maximize the utilization rate of the data transfer path. Starts the process of selecting a replacement method. If both utilization rates are close to 1, it is determined that there is no possibility of improving the utilization rate, and then it is determined whether the difference in data transfer waiting time is equal to or greater than a certain value (step 103). In other words, the cartridge type MT under the control of each control device
The number of input/output requests 44 and the cumulative data transfer waiting time 45 are totaled for each set of 25. The total data transfer waiting time 45 for each set is the total number of input/output requests 44
By dividing by , the average data transfer waiting time of each set can be calculated.

If the difference in average data transfer waiting time is more than a certain value, in order to transfer the cartridge type MT25,
The process branches to step 108. If the above conditions are not satisfied, that is, if there is no possibility of the utilization rate of the data transfer device and if the difference in data transfer waiting time is not more than a certain value, the process is terminated without performing the transfer. let

Next, the process of transferring the cartridge type MT 25 will be described in detail. Normally, in order to satisfy Condition 1 or Condition 2, it is necessary to transfer multiple cartridge-type MT25s, but when multiple MTs are transferred, the transfer pattern increases rapidly, making it difficult to predict The computational overhead becomes extremely large. Therefore, in the following description, a case will be described in which the number of car 1-ridge type MT25 to be transferred is one. Here, one cartridge-type MT25 is selected from a set of cartridge-type MT25s under the control of a control device with a utilization rate of 1 or a control device with a large average data transfer time, and the transfer is executed. . Steps 104 to 107 in Figure 1 are condition 1
This is a process of selecting an MT that satisfies the following, and steps 108 to 1
11 is a process for selecting an MT that satisfies condition 2.

First, the case of selecting an MT that satisfies condition 1 (improvement of utilization rate of data transfer path) will be described. First, in order to perform predictive calculation, one cartridge type MT25 is selected from a set of cartridge type MT25s under the control of a control device whose average data transfer path utilization rate is close to 1 (step 104). ). Finally, when this cartridge-type MT25 is transferred, the utilization rate of the data transfer device with compression/decompression circuit of the set of cartridge-type MT25s under the control of each control device is calculated, and the total value of both is calculated. is calculated (step 105). The number of input/output requests 44, cumulative data transfer time 46, cumulative input/output issue time interval 47, cumulative compressed data transfer amount 48, and cumulative uncompressed data transfer amount 49 for each cartridge type MT25 are shown in the cartridge 1-cartridge type MT table A310.
．． B3], 1, so the cartridge type MT2 under the control of both control devices after the transfer
Average data transfer time for the set of 5, average input/output interval time,
and the compression ratio can be calculated. Furthermore, since the number of MTs belonging to each set after transfer is clear from the number of MTs, it is possible to calculate the utilization rate by using an asymptotic model, a machine repairman model, etc., as described above. It is.

Next, among the car 1 to cartridge type MT25 belonging to the cartridge type MT25 under the control of the control device whose utilization rate is approximately 1, whether there are any remaining cartridge type MT25s that are not subject to the prediction calculation after the transfer. (step 106).

If there are any remaining, the process returns to step 104 and repeats the process. In addition, if there are no remaining cartridge-type MT25s and the prediction calculation has been completed for all cartridge-type MT25s, the cartridge-type MT25 with the highest utilization rate prediction result will be
is selected as the MT to be transferred (step 107).

Next, condition 2 (balance the average data transfer latency)
The MT relocation that satisfies the following will be explained in detail. First of all,
In order to perform predictive calculation, one cartridge-type MT25 is selected from a set of cartridge-type MT25s under the control of a control device with a large average data transfer waiting time (
Step 108). Selected car 1 ~ Ritsuji type MT25
The average data transfer waiting time of the set of cartridge type MTs 25 under the control of each control device after the transfer is calculated, and the difference between the two is determined (step 109). In this case, the number of input/output requests 44, cumulative data transfer time 46, cumulative input/output issue time interval 47, cumulative compressed data transfer rate 48, and cumulative uncompressed data transfer amount 49 of each cartridge 1-cartridge type MT25 are shown in the cartridge type MT table. A310. Since it is clear from B511, it is possible to calculate the average data transfer time, average input/output interval time, and compression ratio of the set of cartridge-type MT25s under the control of both control devices after the transfer. . In addition, since the number of MTs belonging to each set after transfer is clear based on the number of MTs of 80, the average pig transfer time is calculated by using an asymptotic model, a machine repairman model, etc. as described above. Is possible.

Next, among the MTs belonging to the cartridge type MT25 under the control of the control device, which had a large average data transfer waiting time,
It is checked whether there are any items remaining that are not subject to prediction calculation after the transfer (step 110). If there are any remaining, return to step 108 and repeat the process. In addition, if there is no remaining cartridge type MT25 and the prediction calculation of all cartridge type MT25 is completed, the cartridge type MT2 with the smallest difference in the predicted average data transfer waiting time
Select 5 as the MT to be transferred (Step) 11)
.

Finally, the number of input/output requests for each cartridge type MT25 is 44.
, cumulative data transfer time 45, cumulative data transfer waiting time 4
6. Clear the cumulative input/output issue interval time 47, cumulative compressed data transfer amount 48, and cumulative uncompressed data transfer amount 49, and set it to 0.
Make it. After this, the selected cartridge type MT
25 transfer operation begins. When this transfer process is completed, the number of MTs (80) is updated. Note that the transfer operation is not directly related to the gist of the present invention, so a description thereof will be omitted.

FIG. 9 is a processing flowchart for sending necessary information to the other party's control device in order to select a transfer MT in the present invention.

In other words, here is the cartridge type MT25 to be transferred.
The process of the control device that does not execute the process of selecting is shown. This process is carried out from the car 1 to the bridge type MT to be transferred.
This is executed when a request is received from the control device on the side that selects No. 25 to send information necessary for the selection process.

First, to the control device that selects the cartridge type MT25 to be transferred, the number of MTs is 80, and the number of input/output requests of the cartridge type MT25s under the control of this control device is 4.
4, cumulative data transfer waiting time 45, cumulative data transfer time 46, cumulative input/output issue interval time 47, cumulative compressed data transfer amount 48, and cumulative uncompressed data transfer amount 49 (step 900). . Next, the number of input/output requests is 44
, cumulative data transfer waiting time 45, cumulative data transfer time 4
6. Clear the cumulative input/output issue interval time 47, cumulative compressed data transfer amount 4 days, and cumulative uncompressed data transfer amount 49 to O (step 901). After this, in the control device of the other party, the transfer of the car 1 to the bridge type MT 25 is executed according to the prediction calculation result. Once the transfer is complete.

The number of MTs is updated to 80.

In addition, in this example, the car 1 to the rigid type MT25
The transfer is performed every 40-times after a predetermined period of time has elapsed. Therefore, by adding the following process, the number of cartridge-type MT25s under the control of the control device will be zero between the time when the transfer process is executed and the time when the next transfer process is executed. It is possible to reduce the probability.

In other words, the cartridge type MT under the control of the control device
If the number of MT25s is one, if the processing for that cartridge type MT25 is completed within the above time, the number of cartridge type MT25s under the control of the control device becomes 0, and the host system New cartridge type MT
When the processing request No. 25 is not generated, the control device remains idle until the above-mentioned time period elapses. In order to avoid such a case, the following restrictions are placed on transfer so that the number of quadrilateral MT25s under the control of each control device is two or more.

First, the cartridge type MT25 under the control of the control device
For control devices in which the number of units is two or less, the cars 1 to 25 that are under control are excluded from the transfer. At this time, the cartridge type MT
To reduce processing time by not performing post-transfer prediction calculation for No. 25. In addition, if there is a control device in which the number of cartridge-type MT25s under the control of the control device is one or less, the cartridge-type MT25 under the control of that control device
5, it is only necessary to perform predictive calculation after transferring the quadrilateral MT 25 under the control of the control device. As a result, when the number of units reaches one, it is possible to increase the number of units by moving them under the control of that control device, but the number does not become zero by transferring them to the control of another control unit. Also, 2
Once it reaches this level, it is no longer a target and prediction calculations are not performed, so it will not decrease any further.

FIG. 11 is a block diagram of a computer system applying a load balancing control method showing another embodiment 7 of the present invention.

In FIG. 11, reference numeral 1100 denotes a CPU 1101 that issues input/output commands to the cartridge type MT.

1102 are channels A and B, respectively, 1103°110
4 are control devices A and B, respectively, and 1105 is surface control device A.
, B is a cartridge type MT connected to the MT. Although this embodiment is also described as a cartridge type MT as an input/output device, the input/output device is not limited to this.
It can be applied to general input/output devices.

Cartridge type MT1105 is surface control device A1103
, Bll○4, it is possible to transfer data with any control device. However, since each MT of the cartridge type MTIIO 5 is under the control of one of them, data transfer is possible only with the control device under its control. upper system,
Here, data transfer to and from the CPU 100 is executed by a control device that receives an input/output command. Control device B1104
An input/output command to the cartridge type MT1105 under the control of the control device A110 is sent via the channel A11o1.
3, the input/output command is transferred from control device A 1103 to control device B 1104 through communication path 1106 between surface control devices A and B.

In this example, control bags [A1103 and B 13-04
When balancing the input/output load during the period, cartridge type MTs are transferred for load balancing while reducing the internal processing overhead of the input/output system. First, the cartridge type MT110 under the control of the control device A1103
The input/output load of the set of M and Ti 105 under the control of the control device B 1104 is measured. As a result, if there is a difference between the two, an appropriate MT is selected from the set of cartridge-type MTIIOs 5 under the control of each control device and the transfer is executed to balance the two.

In this case, the question is what order of selection should be used to perform the transfer in order to reduce internal processing overhead as an input/output system.

In this embodiment, first, the input/output devices under the control of each control device are divided by the access route from the higher-level system, and in order to reduce communication between the control devices in order to execute input/output commands, It is determined whether the human output load will be balanced if the input/output devices in each input/output device group are relocated. If the input/output loads are balanced as a result of the determination, the set of input/output devices under control is transferred between the control devices while reducing the internal processing overhead of the input/output subsystem according to the transfer method.

FIG. 12 is a diagram showing a program within the control device of the present invention.

The selection order information collection program 120 is stored in the internal memory 1200 of the control device A 1103 and the control device B 1104.
1 and a selection order determination program 1202 are stored. Next, regarding the processing flow of each of these programs,
Explain in detail.

FIG. 13 is a processing flowchart 1 to 1 of the selection order information collection program in FIG. 12.

This selection order information collection program 1201 is executed by a control device that controls an input/output device to be subjected to input/output processing each time an input/output command is received from a host system. Then, the selection order information collection program is read and executed for each input/output device within the control device.

First, it is determined whether the received input/output command is an access from a channel connected to the width control device (step 1).
301). If the access is not from a channel connected to the width control device, 1 is added to the number of accesses from a channel connected to another control device (step 1302
). In the case of access from a channel connected to the width control device, 1 is added to the total number of accesses from the channel (step 1303).

FIG. 14 is a flowchart of the access route determination process.

This process determines whether the access is from a channel connected to a width control device, and this process determines whether the input/output device under the control of each control device is executed against. That is, the first
In FIG. 3, an access route is determined for each input/output device based on the number of accesses from a channel connected to another control device and the total number of accesses from the channel.

First, it is determined whether the total number of accesses from the channel is 0 (step 1401), and the cartridge type M
It is determined whether T1105 is to be transferred in the load balancing process. That is, when the total number of accesses from the channel is 0, the cartridge type MT 1105 is not operating within the measurement time, and is therefore excluded from the transfer target of load balancing processing (step 1502). Furthermore, when the total number of accesses is not O, the car 1 to the bridge type MT1105 are connected to another control device by determining whether the number of accesses from a channel connected to another control device is 0 or not. It is determined whether it is included in the cartridge type MTII05 group accessed only from the channel (step 1403). When the number of accesses from a channel connected to another control device is 0, the cartridge type MT1105 is a cartridge type MT1105 accessed only from the channel connected to the width control device.
Record that it is included in the group (step 1404)
. Further, when the number of accesses from a channel connected to another control device is not O, it is determined whether the total number of accesses from the channel is equal to the number of accesses from a channel connected to another control device (step 14 .05
). This allows the cartridge type M T 1.10
5 is a cartridge type that is accessed from both the channel connected to the width control device and the channel connected to another control device, or is included in the MT1105 group, or the cartridge type that is accessed only from the channel connected to another control device It can be determined whether it is included in the MT1105 group. When the total number of accesses from a channel is equal to the number of accesses from a channel connected to another control device, the cartridge type MT1105 is a cartridge type MT110 accessed only from a channel connected to another control device.
It is recorded that it is included in Group 5 (step 1406).

Furthermore, if the total number of accesses is not equal to the number of accesses from channels connected to other control devices, the cartridge type MT1105 will receive access from both channels connected to the width control device and channels connected to another control device. It is recorded that the accessed car 1-=47 is included in the ridge type MT 1105 group (step 1407).

Through the process shown in FIG. 14, the access route for each input/output device within a predetermined time is determined.

It does not matter which of the control devices A1103 and B1104 selects the cartridge type MT1105 to be transferred. However, it is the cartridge type MT1105 that collects the information regarding the access route shown in Figure 14.
must be the control device that selects the Note that when the difference between the input and output loads of the control devices Al 103 and B 1104 is less than a certain value, it is assumed that the loads are balanced, and the cartridge 1-ridge type MT 1105 is not transferred.

Next, we will discuss the problems when transferring the cartridge type MTII○5.

Normally, in order to best balance the average data transfer waiting time between both control devices, it is necessary to relocate n units (n is an integer of 1 or more) of the carriage type MTs 1105. However, if n units are transferred, the number of transfer patterns increases rapidly, so there is a problem that the overhead of the predicted calculation amount becomes too large. Therefore, in this embodiment, the cartridge type MT1105 to be transferred is
The following explanation assumes that the number of units is one. In other words, one cartridge type MT is selected from among a set of cartridge type MT1105s under the control of a control device with a long average data transfer time.
After selecting 1105, this MT transfer is executed.

FIG. 10 is a processing flowchart of the selection order determination program in FIG. 12.

This selection order determination process is executed following the access route determination process (see FIG. 14) after a predetermined time has elapsed.

First, the car 1- controlled by the transfer destination control device
It is determined whether or not there is a cartridge type MT 11.05 among the ridge type MTs 1105 that has been accessed only from the channel connected to the transfer source control device (step 1001). If there is such a cartridge type MT11.05, among the cartridge type MT1105s controlled by the transfer source control device, the cartridge type MT1105 accessed only from the channel connected to the transfer destination control device. It is determined whether or not there is (step 1002). In addition, such a cartridge type MT1
Even if there is no 105, the same judgment as in Section 2 is made (
Step 1003). That is, it is determined whether or not there is a cartridge type MT 1105 that is accessed only from a channel connected to the transfer destination control device among the cartridge one-cartridge type MTs 1105 controlled by the transfer source control device. These determinations (steps 1,002,1
003), such Kerr 1 to Ritsuji type MT11
05, among the cartridge type MTIIO5s that are all controlled by the transfer source control device, among the cartridge type MT1105s that are accessed only from the channel connected to the transfer destination control device, the control Cartridge type MT1 that balances input and output loads between devices.
105 as the selection target (step 1004..101
．． 0). On the other hand, "2nd judgment (step 1002.100
3) As a result, such Kerr 1 heritage type MT1105
If there is no channel connected to the transfer source control device and the channel connected to the transfer destination control device among the force 1 herriage type MT1.105 controlled by the transfer source control device. Among the cartridge type MTs 1105 accessed from both channels, the car 1 to the cartridge type MTs 1.105 that balance the input/output load between the control devices are selected (step 1007). Next, if an input/output device accessed only from a channel connected to the transfer destination control device is selected (step 1004), and among the transfer destination input/output devices, the transfer source control device If there is no input/output device that is accessed only from the connected channel (step 1.0 O1), the controller 1--rigid MT1 balances the input/output load between the control devices.
105 is present (step 1005).

Furthermore, if the input/output device accessed from both channels is selected (step 1007), it is similarly determined whether there is a cartridge type MT1105 that balances the input/output load between the control devices. (step 1008). In either case, when there is a judgment result.

Finish the process. If there is no determination result (step 1005), among the cartridge type MT11.05 controlled by the transfer source control device, the channel connected to the transfer source control device and the transfer destination control device Among the car 1 to cartridge type MTs 1105 accessed from both channels connected to the device, the cartridge type MT 1105 that balances the input/output load between the control devices is selected (step 1006). Similarly, if there is no determination result (step 1008), among the cartridge type MTIIO5s controlled by the transfer source control device, the cartridge type MT1105 accessed only from the channel connected to the transfer source control device. Then, car 1 to bridge type MT1105, which balance the input/output load between the control devices, are selected (step 1009).
). Then, in both cases, the selection order determination process ends.

After the selection order determination process shown in FIG. 10 is completed, the selection order information shown in FIG. 13 is cleared.

〔Effect of the invention〕

As explained above, according to the present invention, a group of input/output devices connected to a plurality of control devices is provided, each input/output device is under the control of one control device, and only the control device being controlled is provided with a group of input/output devices connected to a plurality of control devices. In a computer system that transfers data to and from the computer, the input/output devices are relocated so that the total throughput or utilization rate of the surface control devices is maximized, and the input/output devices are relocated to balance the load on each control device. Since the input/output load on each control device can be balanced, the internal processing overhead of the input/output system can be reduced, and high performance can be achieved.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention, and FIG. 2 is a block diagram of a computer system to which the present invention is applied, and FIG. Fig. 2 is a configuration diagram of the control device of the car 1 to the rigid type MT, Fig. 4 is a diagram showing information stored in the MT child table in Fig. 3, and Fig. 5 is a diagram showing the timing of input/output request bone in the present invention. Processing flowchart 1., FIG. 6 is a processing flowchart at the start of data transfer in the present invention, and FIG.
8 is a diagram showing the information stored in the control device table in FIG. 3. FIG.
Flowcharts 1 to 1 of the process of transferring necessary information to the other party's control device for selection of T. FIG.
, FIG. 11 is a block diagram of a computer system showing another embodiment of the present invention, FIG. 12 is a diagram showing a program group stored in the memory in the control device in FIG. 11, and FIG. 13 is a block diagram of a computer system showing another embodiment of the present invention. FIG. 14 is a flowchart of the access route determination process that is executed together with the selection order determination process in FIG. 20: CPU, 21, 22: Channels A, B, 23
．． 24: Control device A, B, 25: Car 1-ridge type MT
, 300, 301: Processor A, B, 302.30
3: Buffer 7A, B, 304, 305: Data transfer device with compression/decompression circuit CA, CB, 306.307: Data transfer device DA, DB, 308.309: Control device table A, B, 310°311=force - Toritsuji type MT table A, B, 312: Control information path, 313, 31.4
．． : Prediction information collection function A, B, 315, 316: Prediction calculation execution function A, B, 1100: CPU, 1101, 11
02: Channel) LIA, B, 11.03, 1.104=
Control device A, B, 1105: Cartridge type MT, 12
00: Memory in the control device, 120 ], : Selection order information collection program, 1202: Selection order determination program. fig fig fig fig fig fig fig fig fig fig fig fig fig fig fig fig fig fig fig fig fig fig.

Claims (1)

[Claims] 1. A plurality of control devices connected to each of the plurality of channels, and a group of input/output devices connected to each of the control devices, each input/output device controlling one device at the same time. In a computer system that is under the control of a device and transfers data only to and from the controlled control device, when transferring an input/output device that is under the control of one control device to the control of another control device. , use an analytical model to predict the input/output load status of the set of input/output devices that will be under the control of each control device after the transfer, and before executing the predictive calculation, As a result of the above prediction calculation,
First, select the relocation method that will most likely improve the performance of each control device, and if relocation does not improve performance, then select the relocation method that will best balance the input and output loads. , a load balancing control method characterized in that a set of input/output devices under the control of each control device is transferred according to the result of the selection. 2. The load balancing control method according to claim 1, wherein an asymptotic model or a machine repairman model is used as the analytical model. 3. In the load balancing control method according to claim 1, the information necessary for the prediction calculation includes the average data transfer time for each input/output device, and the next input/output request after the input/output processing of each input/output device is completed. The average interval time to receive the
A load balancing control method characterized by determining the number of input/output devices under control of each control device and the data compression rate. 4. In the load balancing control method according to claim 1, data transfer is started after receiving an input/output request for a set of input/output devices under control of each transferred control device as a result of the predictive calculation. The average response time from receiving an input/output request to the end of data transfer for the set of input/output devices under the control of each controller after transfer is the lowest. A load balancing control method characterized by selecting a short transfer method. 5. In the load balancing control method according to claim 1, the result of the predictive calculation that the performance will be improved is such that the throughput of each control device after the transfer is maximized or the throughput after the transfer is A load balancing control method characterized by selecting a transfer method that maximizes the utilization rate of a data transfer path between each control device and a channel. 6. In the load balance control method according to claim 1, when performing the above prediction calculation, input/output devices under the control of a control device in which the number of input/output devices under control is two or less are not subject to transfer. and do not perform predictive calculations, or
Transfer so that the number of input/output devices under the control of the transfer destination control device is two or more, or if there is a control device with the number of input/output devices under control of one or less. , a load balancing control method characterized by performing only predictive calculation after relocating an input/output device under the control of the control device. 7. Equipped with a plurality of control devices connected to each of the plurality of channels and a group of input/output devices connected to each of the control devices, each input/output device being under the control of one control device at the same time. , in a computer system that transfers data only to and from the control device being controlled, when an input/output device under the control of one control device is transferred to the control of another control device, the transfer is performed by the control device. Determining the selection order of the input/output devices, and before the determination, collecting information including routes accessed from the host system for each control device at a predetermined time necessary for determining the selection order, A load balancing control method characterized by determining a selection order such that input/output loads are balanced, and transferring a set of input/output devices under control between each control device. 8. In the load balancing control method according to claim 7, the selection order includes input/output devices that are accessed only from channels connected to the transfer destination control device, and input/output devices that are accessed only from channels connected to the transfer source control device. The input/output device groups are accessed from both the channel and the channel connected to the transfer destination control device, and the input/output device groups are accessed only from the channel connected to the transfer source control device.
If there is no corresponding input/output device in each input/output device group, or
1. A load balancing control method, characterized in that, when a transfer method that balances input and output loads cannot be obtained, selection is made within a group of input and output devices in the next order. 9. In the load balancing control method according to claim 7, in the selection order, among the input/output devices under the control of the transfer destination control device, access is made only from the channel connected to the transfer source control device. If there are no input/output devices that are under the control of the source control device and that are accessed only from channels connected to the destination control device, A load balancing control characterized in that among input/output devices under the control of a transfer source control device, input/output devices accessed only from a channel connected to the transfer source control device are excluded from selection. Method. 10. In the load balancing control method according to claim 7, in the selection order, among the input/output devices under the control of the transfer destination control device, access is made only from the channel connected to the transfer source control device. There are input/output devices that are
And among the input/output devices under the control of the transfer source control device, if there is an input/output device that is accessed only from the channel connected to the transfer destination control device, the input/output device is under the control of the transfer source control device. 1. A load balancing control method characterized in that, among input/output devices located in a transfer destination, only input/output devices accessed only from a channel connected to a transfer destination control device are selected. 11. In the load balancing control method according to claim 7, as the selection order, the input/output devices are selected in the order of the number of accesses from the channel connected to the transfer destination control device, or the transfer A load characterized in that the input/output devices are selected in the order of input/output devices having a large ratio of the number of accesses only from the channel connected to the transfer destination control device to the number of accesses from the channel connected to the original control device. Balance control method.