Transmission control method, transmission control system

Abstract

The problem lies in providing a transmission control method and a transmission control system that can appropriately monitor and respond to the omen of obstacle occurrence and can suppress the degradation of the performance and redundancy of the overall system. The solution lies in that the transmission control method according to the present invention is characterized in that a parameter for determining the size of the opening of the eye diagram is used to determine the performance of transmission in the transmission line, and based on the result of the determination, the transmission parameter, which is a parameter affecting the transmission quality in the transmission line, is adjusted.

Description

Technical Field

[0001] The present invention relates to a transmission control method and a transmission control system. Background Art

[0002] Conventionally, for example, in a storage system, it has been known that the quality of a transmission signal between devices deteriorates due to breakage or aging of a cable. In addition, it has also been known that a failure occurs due to a cable. Then, as a technique for coping with such a situation, Patent Document 1 discloses a technique for performing path diagnosis in such a manner as not to affect system operation.

[0003] Patent Document 1 discloses a storage system including two controllers, four IO modules, and two storage devices. In response to an input / output request (e.g., a read command or a write command) for a volume from a host device as a superior device, data reading or writing and other processes are performed on a storage device corresponding to the volume. In addition, the controller has a diagnostic function for diagnosing a data transmission path (diagnosis target path) for data transmission and reception between the controller and the IO module, and determines which one of three types of states, namely, "normal state", "precautionary replacement required", and "replacement required", corresponds to a combination of selected equalizer variables.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2017-129969 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] However, in high-speed transmission for connecting between devices (e.g., high-speed transmission related to PCIe), it is considered that even if the technique of Patent Document 1 is used, it is impossible to appropriately monitor the omen of an obstacle occurrence during system operation. As a result, it is impossible to ensure the transmission quality other than during a failure occurrence, and the performance and redundancy of the system as a whole sometimes decrease.

[0009] Therefore, an object of the present invention is to provide a transmission control method and a transmission control system that can appropriately monitor the omen of an obstacle occurrence and respond thereto, and can suppress a decrease in the performance and redundancy of the system as a whole.

[0010] Means for Solving the Problems

[0011] According to the first aspect of the present invention, there is provided a transmission control method as described below. That is, the transmission control method uses a parameter that determines the size of the opening of the eye diagram to determine the performance of transmission in a transmission line, and based on the result of the determination, adjusts a transmission parameter that is a parameter affecting the transmission quality in the transmission line.

[0012] According to the second aspect of the present invention, there is provided a transmission control system as described below. That is, the transmission control system includes a storage unit and a first controller. The first controller is connected to a first transmission line that connects a host computer as a superior device and the storage unit. The first controller executes an adjustment processing program, uses a parameter that determines the size of the opening of the eye diagram to determine the performance of transmission in the first transmission line, and based on the result of the determination, adjusts a transmission parameter that is a parameter affecting the transmission quality in the first transmission line.

[0013] Effect of the Invention

[0014] According to the present invention, there are provided a transmission control method and a transmission control system that can appropriately monitor and respond to omens of obstacles and can suppress a reduction in the performance and redundancy of the system as a whole. Description of the Drawings

[0015] Figure 1 It is a system block diagram for explaining the storage system of the present embodiment.

[0016] Figure 2 It is a flowchart for explaining the processing of the adjustment processing program.

[0017] Figure 3 It is an example of data (threshold table and measurement value table) used in the present embodiment.

[0018] Figure 4 It is an example of data (cycle table) used in the present embodiment.

[0019] Figure 5 It is a flowchart for explaining the processing of the autonomous control processing program.

[0020] Figure 6 It is a diagram for explaining the relationship between programs, data, and hardware in the storage system of the present embodiment.

[0021] Description of Reference Numerals:

[0022] 1 Storage system

[0023] 11 First controller

[0024] 12 Second controller

[0025] 21 First IO device

[0026] 22nd Second IO Device

[0027] 31st First Storage Device

[0028] 32nd Second Storage Device

[0029] 41 Host

[0030] 51 Service Processor

[0031] 61 Adjustment Handler

[0032] 62 Autonomous Control Handler

[0033] 71 Threshold Table

[0034] 72 Measured Value Table

[0035] 73 Period Table Detailed Implementation Manner

[0036] Refer to Figure 1 Describe the configuration of the storage system of this embodiment. The storage system 1 (transmission control system) includes a first controller 11 (computer), a second controller 12, a first IO device 21, a second IO device 22, and a storage unit. The storage unit can be composed of a suitable storage device (such as a hard disk drive). In this embodiment, it is composed of two storage devices (the first storage device 31 and the second storage device 32).

[0037] The first controller 11 includes a CPU and an SW (switch), and is arranged on the transmission line (the first transmission line) connecting the host 41 as a superior device and the first storage device 31. The first IO device 21 includes an LSI (configured as a chipset in this embodiment) and a ROM, and is arranged between the first controller 11 and the host 41.

[0038] The receiving unit for data input to the first controller 11 and the sending unit for data output from the LSI of the first IO device 21 are respectively connected to the transmission line (the first transmission line). In addition, the sending unit for data output from the first controller 11 and the receiving unit for data input to the LSI of the first IO device 21 are respectively connected to the transmission line (the first transmission line). Furthermore, in this embodiment, the connection between the first controller 11 and the first IO device 21 is set to be based on PCIe connection.

[0039] The SW of the first controller 11 is configured to stop the data input to the first controller 11 and the data output from the first controller 11 according to the situation, and is arranged to be controlled by the CPU of the first controller 11. When the data input and output of the first controller 11 stop, the transmission of data on the transmission line (the first transmission line) stops.

[0040] The second controller 12 has the same configuration as the first controller 11. That is, the second controller 12 includes a CPU and an SW (switch). In addition, the second controller 12 is provided on a transmission line (second transmission line) that connects the host 41 and the second storage device 32. The second IO device 22, like the first IO device 21, includes an LSI (configured as a chipset) and a ROM, and is provided between the second controller 12 and the host 41. The connection between the second controller 12 and the second IO device 22 is based on PCIe.

[0041] The SW of the second controller 12 is configured to stop data input to the second controller 12 and data output from the second controller 12 according to the situation, and is set to be controlled by the CPU of the second controller 12. When the data input / output of the second controller 12 stops, the transmission of data on the transmission line (second transmission line) stops.

[0042] In the present embodiment, it is assumed that the first controller 11 and the second controller 12 can communicate. In addition, on the storage system 1, a service processor 51 for system monitoring is connected. Furthermore, the service processor 51 is Figure 1 connected to the first controller 11, but it may also be connected to a controller different from the first controller 11, or may be connected to multiple controllers.

[0043] In the storage system 1 of the present embodiment, as an example, the state of the transmission line between the controller and the IO device is monitored, and control corresponding to the state is executed. Next, with reference to Figure 2 this control will be described in detail. Figure 2 It is a flowchart for explaining the processing of the adjustment processing program.

[0044] The controller measures the eye diagram of the transmission line between it and the IO device, and obtains an internal eye value (S101). For example, the first controller 11 measures the eye diagram of the transmission line between it and the first IO device 21 by executing the adjustment processing program 61, and obtains the internal eye value of this transmission line. On the other hand, the second controller 12 executes the adjustment processing program 61, measures the eye diagram of the transmission line between it and the second IO device 22, and obtains the internal eye value of this transmission line. In addition, the timing of obtaining the internal eye value (in other words, the timing of performing the processing of S101) can be appropriately determined. In the present embodiment, it is determined by executing the autonomous control processing program 62 described later, and the internal eye value is obtained.

[0045] Here, the above-mentioned internal eye value will be specifically described. The internal eye value is a parameter that determines the size of the opening of the eye diagram. The internal eye value only needs to be able to appropriately evaluate the size of the opening of the eye diagram, and its calculation method is not particularly limited. In the present embodiment, the internal eye value is calculated based on the pre-prepared data and the actually measured and obtained data.

[0046] That is, as Figure 3 shown, prepare the data of the determined opening of the eye diagram (in Figure 3 it is the threshold table 71). This data can be set, for example, as data based on the vendor specifications (that is, the specifications preferred by the vendor providing services, etc.). Then, compare the data obtained from the actually measured eye diagram (in Figure 3 it is the measurement value table 72) with the prepared data, and calculate the internal eye value as a percentage (%) based on the view of whether it is similar to the eye diagram determined by the prepared data.

[0047] Here, in the present embodiment, the smaller the value of the percentage (%) (that is, the smaller the internal eye value), the more similar the opening of the measured eye diagram is to the opening of the eye diagram determined by the prepared data (that is, the better the opening of the eye diagram is opened). On the contrary, the larger the value of the percentage (%) (that is, the larger the internal eye value), the less similar the opening of the measured eye diagram is to the opening of the eye diagram determined by the prepared data (that is, the opening of the eye diagram is not well opened).

[0048] As Figure 3 shown, in the present embodiment, in the threshold table 71 as the prepared data, for each type of signal, data for determining the size of the opening of the eye diagram is set (in Figure 3 it, as an example, is the data of the lengths in the up, down, left, and right directions based on the representative center position of the opening). In addition, in the measurement value table 72, corresponding to the threshold table 71, for each type of signal, data for determining the opening of the eye diagram is also set. Therefore, in the present embodiment, the internal eye value can be obtained for each type of signal.

[0049] As an example, the internal eye value can also be calculated based on the height of the opening (that is, the length in the up and down directions of the opening) and the width of the opening (that is, the length in the left and right directions of the opening), thereby calculating a reasonable internal eye value. However, the internal eye value can also be calculated by a method different from this calculation method (for example, only using the height of the opening). In addition, the comparison with the prepared data can also be omitted, and the internal eye value can be directly calculated based on the measured data.

[0050] The controller determines whether the internal eye value is 30% or more (S102). If the internal eye value is not 30% or more, the processing of the adjustment processing program 61 ends. On the other hand, when the internal eye value is 30% or more, the processing of S103 is executed.

[0051] That is, the controller determines whether the internal eye value that meets the condition of the processing of S102 is less than 50% (S103). Here, when it is determined that the internal eye value is less than 50%, the processing of S104 is executed. On the other hand, when the internal eye value is 50% or more, the processing of S111 is executed.

[0052] When it is determined in the processing of S103 that the internal eye value is less than 50%, the controller adjusts the transmission parameter so that the internal eye value is less than 30%. Here, the transmission parameter is a parameter that affects the transmission quality in the transmission line.

[0053] When the controller adjusts the transmission parameter, it first notifies other controllers (S104). For example, when the first controller 11 obtains an internal eye value of 30% or more and less than 50%, it notifies the second controller 12. In addition, in the following description, the controller that receives the notification in the processing of S104 is sometimes referred to as the notification receiving controller.

[0054] The controller receives data from the controller (notification receiving controller) notified in the processing of S104, and confirms the operation state of the notification receiving controller (S105). That is, the controller confirms whether the following conditions are met: the notification receiving controller has not adjusted the transmission parameter, and the transmission between the host 41 and the storage unit (the second storage device 32 in this embodiment) has been established on the transmission line of the notification receiving controller side.

[0055] In addition, in the processing of S104 and the processing of S105, communication can be directly performed between controllers or via the service processor 51. Then, when it is confirmed that the transmission parameter has not been adjusted and the transmission between the host 41 and the storage unit has been established, the processing of S106 is executed. On the other hand, when this confirmation cannot be made, the processing of S104 is executed again.

[0056] The controller stops the input / output of data (S106). That is, the CPU of the controller controls the SW to stop the input / output of data and stop the transmission of data in the transmission line. For example, when the first controller 11 stops the input / output of data, the transmission of data in the first transmission line stops.

[0057] After the controller stops the input / output of data in the process of S106, it adjusts the internal eye value (S107). That is, the controller adjusts the transmission parameters so that the internal eye value determined to be 30% or more in the process of S102 is less than 30%. Here, the controller can also adjust the parameters of the high-frequency component and the low-frequency component of the adjustment signal as the transmission parameters to adjust the internal eye value. In addition, the controller can also adjust the parameter of the adjustment signal strength as the transmission parameter to adjust the internal eye value.

[0058] After the controller adjusts the internal eye value in the process of S107, it confirms whether the adjusted internal eye value becomes less than 30% (S108). If it fails to confirm that the internal eye value is less than 30%, the controller performs the adjustment of the internal eye value again.

[0059] After the controller confirms that the internal eye value is adjusted to be less than 30%, it notifies other controllers (S109). Then, the controller controls the SW to start the input / output of data in order to enable data transmission in the transmission line (S110). In addition, the process of S119 described later is executed after the process of S110.

[0060] Next, the process in the case where the internal eye value is determined to be 50% or more in the process of S103 is described. In this case, the controller notifies the microprocessor (the component corresponding to the service processor 51) of the failure state (S111). That is, it notifies the microprocessor that a failure is determined. Then, the controller confirms whether the internal eye value on the receiving unit side is 50% or more (S112). For example, in the case where the internal eye value in the transmission line connecting the transmitting unit of this controller and the receiving unit of the IO device is 50% or more, the controller confirms whether the internal eye value on the receiving unit side of the IO device is 50% or more. In addition, the result of the confirmation process in S112 is notified to the user by an appropriate method. The confirmation result is output to an external device via the service processor 51, for example, and is notified to the user.

[0061] Then, the user who has obtained the confirmation result performs a package replacement of the receiving unit or the transmitting unit of the controller (that is, a replacement of the package unit related to the object configuration). For example, when the user grasps that the internal eye value on the receiving unit side is not 50% or more based on the confirmation result, the user performs a package replacement of the transmitting unit (S113). For example, when the user grasps that the internal eye value on the receiving unit side is not 50% or more in the transmission line connecting the transmitting unit of the controller and the receiving unit of the IO device, the user performs a package replacement of the transmitting unit of the controller. On the other hand, when the user grasps that the internal eye value on the receiving unit side is 50% or more based on the confirmation result, the user performs a package replacement of the receiving unit (S114).

[0062] Then, when the transmitting unit is replaced in the process of S113, the internal eye value on the transmitting unit side is confirmed (S115). Then, when the internal eye value is 30% or more, the user is notified of this situation (S117), and the user replaces the transmitting unit again. On the other hand, when the internal eye value is less than 30%, the process of S119 is executed.

[0063] When the receiving unit is replaced in the process of S114 above, the internal eye value on the receiving unit side is confirmed (S116). Then, when the internal eye value is 30% or more, the user is notified of this situation (S118), and the user replaces the receiving unit again. On the other hand, when the internal eye value is less than 30%, the process of S119 is executed.

[0064] In the process of S119, the set number of times, which is the number of times to make the internal eye value of 30% or more normal (that is, make the internal eye value less than 30%), is incremented, and the result is stored in the cycle table 73 described below. Next, refer to Figure 4 the description cycle table, and the process of S119 will also be described.

[0065] Similar to the threshold table 71 and the measurement value table 72, the cycle table 73 stores data for each type of controller and signal. The cycle table 73 stores the cycle T and the set number of times i for each type of signal. Here, the cycle T is the cycle for obtaining the internal eye value when the corresponding signal is transmitted by executing the adjustment processing program 61. In addition, the cycle T can also be appropriately set by the user, but in this embodiment, the cycle T is changed based on the set number of times i by executing the autonomous control processing program 62 described later.

[0066] In the periodic table 73, the set number i stores the value incremented by performing the process of S119 in the adjustment processing program 61. Therefore, in the adjustment processing program 61, in a state where none of the processes of S110, S117, and S118 are executed, the value "0" is stored. Then, when a certain process is executed in this state, the increment in the process of S119 is executed, and the value "1" is stored.

[0067] In the present embodiment, the timing of executing the process of the above-described adjustment processing program 61 (in other words, the start timing of S101) is determined by executing the autonomous control processing program 62. Then, by executing the autonomous control processing program 62, a process of obtaining and monitoring the internal eye value during system operation (i.e., autonomous control processing) is performed, and automatic adjustment of transmission parameters, failure determination, etc. are executed according to the situation. Next, refer to Figure 5 Describe the process of the autonomous control processing program 62. Figure 5 It is a flowchart for explaining the process of the autonomous control processing program.

[0068] The controller executes the autonomous control processing program 62 to confirm the period of the device (that is, the period T of each signal in the periodic table 73) (S201). In addition, the controller confirms the set number i of each signal stored in the periodic table 73 (S202). Then, when the set number i is "0" (S203), the adjustment processing program 61 is executed with the period T corresponding to the set number i in the periodic table 73, and the internal eye value is obtained (S204).

[0069] On the other hand, when the set number i is not "0" (S203), it is determined whether the set number i is 1 to 6 (S205). When the set number i is 1 to 6, the adjustment processing program 61 is executed with the period T corresponding to the set number i in the periodic table 73, and the internal eye value is obtained (S206), and a process related to the change of the period T is performed (S207 to S209). In addition, when the set number i is not 1 to 6 (that is, when the set number i is 7), the adjustment processing program 61 is not executed, but the process of setting the set number i to "0" (S210) and the process of changing the period T (S211) are executed.

[0070] Here, specifically describe the process of the autonomous control processing program 62 in the case of the periodic table 73 shown in Figure 4 shown.

[0071] In the periodic table 73, the set number i of PCIE_RX(0, 2, 4, 6) is "0", so the controller (in Figure 4The controller on the IC1 side obtains the internal eye value in the transmission line when transmitting these signals at a cycle T (here, 30 minutes) corresponding to these signals, and determines whether the internal eye value is less than 30%. Here, when the internal eye value is less than 30%, the set number i on the cycle table 73 is not changed, and the process is performed again after 30 minutes.

[0072] On the other hand, when the internal eye value is 30% or more and the processes of S110, S117, and S119 are performed, the set number i on the cycle table 73 is incremented (that is, the set number i of PCIE_RX(0, 2, 4, 6) becomes "1"). In the subsequent process (that is, after 30 minutes), since the set number i of PCIE_RX(0, 2, 4, 6) is "1", in S206, the internal eye value is obtained and determined. Here, when the internal eye value is less than 30%, the set number i of PCIE_RX(0, 2, 4, 6) remains "1" without change, and when the internal eye value is 30% or more and is incremented in the process of S119, the set number i of PCIE_RX(0, 2, 4, 6) becomes "2".

[0073] Then, the controller (the controller on the IC1 side in Figure 4 calculates the product of the cycle T and the set number i (S207), and determines whether the product of the cycle T and the set number i is equal to the value of the constant t (S208). Here, the constant t is a preset parameter, and the value of the constant t is a multiple of the cycle T and can be selected from the values of T, 2T, 3T, 4T, 5T, 6T.

[0074] When the set number i of PCIE_RX(0, 2, 4, 6) is "1", in the process of S207, t = T×1 is calculated, and the controller (the controller on the IC1 side in Figure 4 determines whether it is equal to the set constant t in the process of S208. On the other hand, when the set number i of PCIE_RX(0, 2, 4, 6) is "2", in the process of S207, t = T×2 is calculated, and the controller determines whether it is equal to the set constant t in the process of S208. Then, when it is equal to the set constant t, the cycle T is not changed. On the other hand, when it is not equal to the set constant t, the setting is made to make the cycle T longer. In the example of Figure 4 , in S209, a process of making the cycle T longer by 30 minutes is performed, and the cycle T of PCIE_RX(0, 2, 4, 6) on the cycle table 73 is changed (that is, in this example, the cycle T becomes 60).

[0075] In addition, when the set number of times i is 7 times (that is, when the condition of S205 is not satisfied), a reset process (initialization process) of the set number of times and the cycle is performed. That is, the set number of times i that becomes 7 times in the cycle table 73 becomes "0" (S210), and the corresponding cycle T is changed to 30 (S211).

[0076] As Figure 6 (A diagram for explaining the relationship between programs, data, and hardware) As shown, the above-described adjustment processing program 61 can be appropriately executed by the CPUs of the first controller 11 and the second controller 12, and can be stored in an appropriate recording medium. The same applies to the autonomous control processing program 62. For example, a recording medium (such as a ROM) can be provided in each of the first controller 11 and the second controller 12, and these programs can be stored in each recording medium, or a recording medium (such as an external HDD) can be provided outside the first controller 11 and the second controller 12, and these programs can be stored in this recording medium. In addition, in Figure 6 each controller is denoted as CTL1 / 2.

[0077] The threshold table 71, the measurement value table 72, and the cycle table 73 only need to be appropriately used in the above-described program processing and can be stored in an appropriate recording medium. For example, a recording medium (such as a ROM) can be provided in each device to store the data related to these tables, or a recording medium (such as a ROM is provided in the controller) can be provided in a specific device to store the data related to these tables. Additionally, a recording medium can be provided in the service processor 51 to store these tables in this recording medium.

[0078] In the above description, the process of obtaining the internal eye value and performing adjustment and other processes (that is, the process related to the adjustment processing program 61) in the transmission line between the controller and the IO device has been described, but the same process can also be performed in the transmission line between the controller and the storage unit. Additionally, in this case, the process can also be performed by the autonomous control processing program 62.

[0079] In the above description, the processing using the reference value (the first reference value) of 30% of the internal eye value and the reference value (the second reference value) of 50% of the internal eye value has been described. However, as long as it is possible to appropriately determine whether the transmission state is appropriate, whether the transmission parameters should be adjusted, or whether the receiving unit or the transmitting unit should be replaced, the magnitude of the reference value of the internal eye value can also be appropriately changed. Here, the first reference value is the reference value of the internal eye value used to determine whether the internal eye value is normal. In the present embodiment, it is the reference value used in the processing of S102 described above. The second reference value is the reference value of the internal eye value used to determine whether to perform the automatic adjustment processing of the internal eye value or whether to regard it as a failure of the device and notify the user or the like of this situation. In the present embodiment, it is the reference value used in the processing of S103 described above. In addition, as long as the threshold determination is performed using the reference value of the internal eye value, it is possible to appropriately set whether the reference value is included (for example, set to be below the reference value or set to be less than the reference value).

[0080] The eye diagram can be measured by using an appropriate method. For example, a measuring device can be provided on the transmission line, and the eye diagram can be measured using this measuring device.

[0081] In the present embodiment, the storage unit is composed of two storage devices (the first storage device 31 and the second storage device 32), but it can also be composed of three or more storage devices, or can be composed of one storage device. In this case (when the storage unit is composed of one storage device), each transmission line is connected to the common storage device. In addition, in the present embodiment, two transmission lines have been described, but it can also be configured to include three or more transmission lines. In addition, a controller and an IO device are provided on each transmission line, and each transmission line is connected to an individual storage device or a common storage device as an example.

[0082] In the prior art, in high-speed transmission between devices (such as high-speed transmission like PCle), it is difficult to perform appropriate premonition monitoring during system operation and appropriate adjustment of transmission parameters during system operation. Therefore, from the perspective of reducing the performance and redundancy of the system as a whole, there is still room for improvement. In contrast, according to the technology of the present embodiment, by using the internal eye value, it is possible to perform appropriate premonition monitoring during system operation (that is, the premonition of obstacle occurrence and the detection of failures), and moreover, appropriately adjust the transmission parameters according to the situation during system operation. Therefore, it has the advantages of being able to maintain the transmission quality and being able to suppress the reduction of performance and redundancy during system operation.

[0083] In addition, when there are differences in the specifications of devices (that is, there are differences in the support for specifications among the devices mounted on the substrate), only standard transmission parameters that do not differ among the devices (for example, values related to emphasis or equalizer) can be set (adjusted). Therefore, in the prior art, in devices that do not support changes in emphasis or equalizer, or in which such changes are not recommended, it is considered that appropriate premonition monitoring may not be possible and the transmission parameters may not be adjusted properly. In contrast, according to the present embodiment, by using the internal eye value, appropriate premonition monitoring can be performed and the transmission parameters can be adjusted properly.

[0084] The embodiments have been described above, but the present invention is not limited to the above-described embodiments and includes various modifications. For example, additions, deletions, and replacements of other configurations can be made to a part of the configuration of the embodiment.

[0085] As an example of the processor, a CPU can be considered, but as long as it is a subject that executes prescribed processing, it can also be other semiconductor devices (for example, GPU).

Claims

1. A transmission control method, characterized in that the storage unit, the first controller, and the second controller are used to execute the transmission control method. The first controller is connected to a first transmission line that connects a host as a superior device and the storage unit, and the second controller is connected to a second transmission line that connects the host and the storage unit. The first controller and the second controller can communicate with each other. The first controller uses a parameter that determines the size of the opening of the eye diagram to determine the transmission performance in the first transmission line. Based on the determination result, the transmission parameter, which is a parameter affecting the transmission quality in the first transmission line, can be adjusted. The second controller uses a parameter that determines the size of the opening of the eye diagram to determine the transmission performance in the second transmission line. Based on the determination result, the transmission parameter, which is a parameter affecting the transmission quality in the second transmission line, can be adjusted. The first controller when adjusting the transmission parameter, notifies the second controller and obtains data from the second controller. confirms whether the second controller has not adjusted the transmission parameter and whether the transmission between the host and the storage unit in the second transmission line on the second controller side has been established. after confirming that the transmission has been established, stops the data transmission in the first transmission line. after adjusting the transmission parameter, resumes the data transmission in the first transmission line.

2. The transmission control method according to claim 1, characterized in that the parameter used by the first controller and the second controller to determine the size of the opening of the eye diagram is determined based on the height and width of the opening.

3. The transmission control method according to claim 1, characterized in that the determination of the first controller is based on a first reference value and a second reference value that determine the size of the opening of the eye diagram. when the second reference value is a reference value that determines the size of an opening smaller than the size of the opening determined by the first reference value. when it is determined by the determination of the first controller that the size of the opening of the eye diagram is smaller than or equal to the first reference value, and the size of the opening of the eye diagram is larger than or equal to the second reference value, the transmission parameter is adjusted.

4. The transmission control method according to claim 3, characterized in that when it is determined that the size of the opening of the eye diagram is smaller than or equal to the second reference value, the transmission parameter is not adjusted, but the user is notified.

5. The transmission control method according to claim 1, characterized in that the determination of the first controller is executed periodically.

6. The transmission control method according to claim 5, characterized in that the period is changed in a manner that becomes longer corresponding to the number of times the transmission parameter has been adjusted.

7. A transmission control system, characterized in that, Comprising: a storage unit; and The first controller is connected to a first transmission line that connects to a host, which is a superior device, and the storage unit. The second controller is connected to a second transmission line that connects to the host and the storage unit. The first controller and the second controller can communicate with each other. The first controller uses a parameter that determines the size of the opening of the eye diagram to determine the transmission performance in the first transmission line. Based on the result of the determination, it can adjust the transmission parameter, which is a parameter that affects the transmission quality in the first transmission line. The second controller uses a parameter that determines the size of the opening of the eye diagram to determine the transmission performance in the second transmission line. Based on the result of the determination, it can adjust the transmission parameter, which is a parameter that affects the transmission quality in the second transmission line. The first controller When adjusting the transmission parameter, notifies the second controller and obtains data from the second controller. Confirms whether the second controller has not adjusted the transmission parameter and whether the transmission between the host and the storage unit in the second transmission line on the second controller side has been established. After confirming that the transmission has been established, stops the data transmission in the first transmission line. After adjusting the transmission parameter, resumes the data transmission in the first transmission line.

8. The transmission control system according to claim 7, wherein The first controller Makes a determination based on a first reference value and a second reference value that determine the size of the opening of the eye diagram. When the second reference value is a reference value that determines a smaller opening size compared to the opening size determined by the first reference value, if it is determined that the opening size of the eye diagram is smaller than or equal to the first reference value and the opening size of the eye diagram is larger than or equal to the second reference value, the transmission parameter is adjusted.

9. The transmission control system according to claim 8, wherein The first controller is connected to a service processor and can communicate with the service processor. The first controller When it is determined that the opening size of the eye diagram is smaller than or equal to the second reference value, does not adjust the transmission parameter but notifies the service processor.

10. The transmission control system according to claim 7, wherein The first controller Determines the transmission performance in the first transmission line at regular intervals.

11. The transmission control system according to claim 10, wherein The first controller Changes the period so that the period becomes longer corresponding to the number of times the transmission parameter has been adjusted.

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