Shared Storage Management Device and Shared Storage Management Method

Abstract

To provide a system having a shared storage shared by a plurality of applications, configured to allow for efficient use of storage areas of the shared storage.SOLUTION: A shared storage management apparatus (2) which is equipped in a system having a shared storage (11) to be used by a plurality of applications for writing or reading data, includes a storage management section (10) configured to adjust securing and releasing storage areas of the shared storage in response to requests from the applications. The storage management section sets static release priority for each of the storage areas secured in the shared storage, and issues an instruction to release the storage areas in descending order of the release priority when a request for securement is received from an application and there is no sufficient storage area to be secured in the shared storage.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a shared storage management device and a shared storage management method in a system mounted on a vehicle such as an automobile.

Background Art

[0002] For example, a vehicle such as an automobile is provided with a system configured by network-connecting various electronic control devices called a plurality of ECUs (Electronic Control Units) including a computer via CAN, Ethernet, or the like. Each ECU is provided with a plurality of applications, and information is exchanged between these applications. In addition, some ECUs include communication devices capable of communicating with the outside of the vehicle, and data is also transmitted and received to and from external devices. For example, data of a drive recorder is uploaded to the cloud, or an update program and various data are downloaded from the outside.

[0003] At this time, when each application performs downloading or uploading, it temporarily uses a storage area, but there is a situation where it is wasteful to prepare a dedicated storage area in each ECU. Therefore, for example, a shared storage is provided in one ECU, and a plurality of applications write and delete data to and from the shared storage at an arbitrary timing. In this case, generally, in order to adjust access from a plurality of applications to the shared storage, a mediation unit is provided (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, after each application finishes the processes of uploading and downloading, it determines that the data has become unnecessary and performs a process of deleting it from the storage area of the shared storage. As described above, when the shared storage is shared and used by a plurality of applications, if the use of the shared storage becomes concentrated, even if another application tries to use the shared storage, a situation may occur where the free capacity of the storage area is insufficient and cannot be used. In this case, if waiting until another application finishes using the shared storage, the area will become free and the use of the shared storage will be possible, but the utilization efficiency of the shared storage will deteriorate. In Patent Document 1 described above, no consideration was given to how to deal with such a situation where the free capacity is insufficient.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a shared storage management device and a shared storage management method that enable efficient use of the storage area of a shared storage in a system including a shared storage shared by a plurality of applications.

Means for Solving the Problems

[0007] In order to achieve the above object, the shared storage management device (2) of the present invention includes one or more computers (2, 3, 4) including those having a communication function with the outside in a closed network (5), and a plurality of applications (7, 8, 9) on each computer exchange information with each other, and is provided in a system having a shared storage (11) used by the plurality of applications for writing and reading data. The shared storage management device includes a storage management unit (10) that adjusts the securing and releasing of the storage area of the shared storage according to the requests of the respective applications. The storage management unit sets a release priority for each storage area secured in the shared storage, and when there is a request for securing from the application and the storage area to be secured in the shared storage is insufficient, it instructs the release in order from the storage area with the highest release priority.

[0008] Note that the "release of the storage area" mentioned here not only includes deleting the stored data, but also other processes such as compressing the stored data to secure free space, or changing the state of the storage area secured by a certain application to a state where free space can be secured even if there is actually no data in it.

[0009] According to the above configuration, the storage management unit adjusts the securing and releasing of the storage area of the shared storage according to the requests of each application. At this time, the storage management unit sets a release priority for each storage area secured in the shared storage. Here, for example, when the use of the shared storage may be concentrated among a plurality of applications, when there is a request for securing from another application, there may be a case where the storage area to be secured in the shared storage is insufficient. At this time, the storage management unit instructs the release in order from the storage area with the highest release priority.

[0010] As a result, without waiting for the data in the shared storage to be deleted by the application, the storage management unit releases the storage areas with the highest release priority in order, and according to the request of the application, the storage area can be quickly released to secure the necessary storage area. As a result, it has an excellent effect of enabling efficient use of the storage area of the shared storage in a system equipped with a shared storage shared by a plurality of applications. In addition, when there are a plurality of area securing requests for which no storage area has been secured, the storage management unit sets the securing priority of these area securing requests based on conditions including one or more of the area securing request capacity, the request order, the nature of the data, and the current free capacity of the shared storage. In this setting, The ratio of the area securing request capacity to the free capacity consider and executes the securing process in order from the one with the highest securing priority.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0012] (1) First Embodiment Hereinafter, a first embodiment applied to a shared storage management device in an in-vehicle system mounted on a vehicle such as an automobile will be described with reference to FIGS. 1 to 4. FIG. 1 schematically shows the configuration of the in-vehicle system 1 in this embodiment. Here, the in-vehicle system 1 is configured by connecting a plurality of ECUs (Electronic Control Units) 2, 3, and 4 to each other via a network 5 such as CAN (registered trademark) or Ethernet (registered trademark). The ECUs 2, 3, and 4 include a computer. For the sake of convenience, only three ECUs 2, 3, and 4 are shown in FIG. 1.

[0013] Among them, ECU3 is an ECU for communication control with the outside of the vehicle. It is equipped with an in-vehicle communication device 6 called DCM (Data Communication Module) and also mounts an application 7. The ECU4 is an ECU for controlling various in-vehicle devices, and includes, for example, an ECU for running control systems such as engine control, an ECU for body system control, an ECU for navigation control, an ECU for ETC control, an ECU for audio control, an ECU for driving recorder control, and the like. This ECU4 mounts an application 8.

[0014] The ECU2 is, for example, an ECU for a central gateway and has a function as a hub in the network of the in-vehicle system 1. This ECU2 mounts an application 9. A plurality of applications may be provided in each of the ECUs 2, 3, and 4. As will be described in detail later, in this embodiment, this ECU2 functions as a shared storage management device. Incidentally, the above applications 7, 8, and 9 may be simply abbreviated as "app" as necessary. In FIG. 1, the application 7 is denoted as "App A", the application 8 is denoted as "App B", and the application 9 is denoted as "App C".

[0015] In the in-vehicle system 1 of this embodiment, the plurality of applications 7, 8, and 9 of the respective ECUs 2, 3, and 4 exchange information with each other. Although not shown in detail, communication is performed with a center device of an external service company or the like via a communication network by the in-vehicle communication device 6. In this case, the plurality of applications 7, 8, and 9 of each of the ECUs 2, 3, and 4 perform processes such as uploading and downloading to the center device.

[0016] Specifically, the information transmitted to the center device includes diagnostic data detected by various in-vehicle sensors, data of a driving recorder, and the like. Also, the information received from the center device includes a software update program for each in-vehicle device, map data for navigation updated at an arbitrary timing among the information referred to by each in-vehicle device, music data reproduced by an audio device, and the like.

[0017] At this time, when each of the applications 7, 8, and 9 performs data download or upload, it temporarily uses the memory area. However, in each of the ECUs 2, 3, and 4, there is a situation where it is often a waste to prepare a dedicated memory area. Therefore, for example, in one ECU, in this case, the central gateway ECU 2, a shared storage 11 is provided. The plurality of applications 7, 8, and 9 write and delete data to and from the shared storage 11 at arbitrary timings.

[0018] Now, the function as a shared storage management device in the ECU 2 will be described. As described above, the ECU 2 is provided with the shared storage 11. Along with this, the ECU 2 is provided with a storage management unit 10 that adjusts the securing and releasing of the storage area of the shared storage 11 in accordance with the requests of each of the applications 7, 8, and 9. The storage management unit 10 includes a storage management table 12. In the present embodiment, the storage management table 12 stores management information including the application that requested the securing of the shared storage 11, the capacity of the secured storage area, data of the static release priority in each storage area, and the like.

[0019] Along with this, the storage management unit 10 realizes functions as a request reception unit 13, an area securing processing unit 14, an area management unit 15, an area release processing unit 16, and a priority determination unit 17 by its hardware and software configuration. Specifically, as will also be described in the subsequent operation explanation, the request reception unit 13 executes a process of receiving requests for securing and releasing the storage area of the shared storage 11 from each of the applications 7, 8, and 9.

[0020] The area reservation processing unit 14 reserves a storage area of the shared storage 11 in accordance with the reservation request for the storage area received by the request reception unit 13. At this time, when reserving the storage area of the shared storage 11, the area reservation processing unit 14 assigns a release priority to the storage area. In the present embodiment, the release priority is a static release priority set based on at least one of the nature of the data to be used, for example, whether it is upload or download, and whether the area reservation request capacity of the data exceeds a predetermined capacity, for example, 200 MB or less. In the case of download, the release priority is set higher than in the case of upload, and when the area reservation request capacity of the data exceeds the predetermined capacity, the release priority is set even higher. For example, the release priority determined based on the information that has already been determined at the time when the request reception unit 13 receives the request for reserving the storage area of the shared storage 11 from each of the applications 7, 8, and 9 is called the static release priority.

[0021] Then, when reserving a storage area, the area reservation processing unit 14 inquires of the area management unit 15 about the free area of the shared storage 11, and if it is determined that the required storage area is insufficient, requests the area management unit 15 to release an existing storage area. The area management unit 15 writes the management information of the area of the shared storage reserved by the area reservation processing unit 14 into the storage management table 12. Further, when the request reception unit 13 receives a release request from the applications 7, 8, and 9, the area management unit 15 instructs the area release processing unit 16 to release the area.

[0022] At the same time, when the area management unit 15 is requested by the area reservation processing unit 14 to release an existing storage area, it requests the priority determination unit 17 to determine the release priority, and in order from the area with the highest release priority, instructs the area release processing unit 16 to release the area. The area release processing unit 16 performs a process of releasing the storage area of the shared storage 11 for which a release request has been made in accordance with the release instruction from the area management unit 15. Further, when the release of the storage area is completed, the area management unit 15 deletes the information of the storage area from the management information in the storage management table 12.

[0023] When the priority determination unit 17 receives a request from the area management unit 15 when the request reception unit 13 receives a request to secure a storage area in the shared storage 11, it determines the release priority of the storage areas to be released in the shared storage 11. As a result, when there are requests to secure storage areas from the applications 7, 8, and 9, if there is a shortage of storage areas to be secured in the shared storage 11, the storage management unit 10 instructs releases in order from the storage areas with the highest release priority.

[0024] Note that the "release of storage area" as referred to here includes not only deleting the stored data, but also other processes such as compressing the stored data to secure free space, or changing the state of an area in the storage area secured by an application to a state where free space can be secured even if there is no actual data in it.

[0025] Next, the processing executed by the storage management unit 10 with the above configuration will be described with reference to FIGS. 2 to 4. Among them, the flowchart of FIG. 2 shows the processing procedure for securing a storage area executed by the storage management unit 10. Also, the flowchart of FIG. 3 shows the processing procedure for releasing a storage area executed by the storage management unit 10 when an application requests the release of a storage area. The flowchart of FIG. 4 shows the detailed processing procedure for the release request of the existing storage area in step S3 of FIG. 2. Through these processes, the shared storage management method according to the present embodiment is executed.

[0026] That is, first, in FIG. 2, at step S1, when a secure request is received, at step S2, in the area securing processing unit 14, it is determined whether there is free capacity necessary to secure the capacity of the storage area requested by the application in the shared storage 11. In other words, it is determined whether there is sufficient free capacity in the shared storage 11 for the capacity of the storage area requested by the application. Here, if it is determined that there is no free capacity necessary to secure the capacity of the storage area requested by the application in the shared storage 11 (No at step S2), then at the next step S3, the process of releasing the existing area is performed, and then the process proceeds to step S4. The details of the release process in this step S3 will be described later with reference to FIG. 4.

[0027] At step S2, if it is determined that there is sufficient free capacity in the shared storage 11 (Yes at step S2), then at step S4, the area securing processing unit 14 secures a storage area of the requested amount in the shared storage 11. Along with this, at step S5, a static release priority is set for the secured storage area. The release priority is set based on the nature of the data used or the capacity of the data area secure request as described above. That is, in the case of download, the release priority is set higher than in the case of upload, and when the capacity of the data area secure request exceeds a predetermined capacity, for example, 200 MB, the release priority is set even higher. At step S6, management information is registered in the storage management table 12, and the process ends.

[0028] Next, in FIG. 3 showing the processing procedure when the application requests memory area release, at step S11, a release request for the area secured by any of the applications 7, 8, 9 is received by the request reception unit 13. Then, at step S12, the area management unit 15 collates the information of the memory area to be released in the storage management table 12 from the information of the application with the release request and the memory area to be released. At the next step S13, the area release processing unit 16 receives the information of the memory area to be released from the area management unit 15 and releases the corresponding memory area of the shared storage 11. After the release is performed, at step S14, the corresponding management information is deleted from the storage management table 12 by the area management unit 15, and the process ends.

[0029] The flowchart of FIG. 4 shows the details of the processing procedure in step S3 of FIG. 2, that is, when the existing memory area is released in the storage management unit 10. In step S21, when the area management unit 15 receives a memory area release instruction from the area securing processing unit 14, at step S22, a priority determination is requested from the priority determination unit 17, and the release priority of each memory area in the storage management table 12 is determined. In step S23, the memory area with the highest priority is extracted as the area to be released. Here, note that the target of the priority determination at this time includes not only the already secured memory areas but also the areas for which a new securing request has been received.

[0030] At the next step S24, it is determined whether the extracted area to be released is an area for which a new securing request has been received, that is, whether it is an existing secured area. If the extracted area to be released is an existing secured area (Yes at step S24), at step S25, the release of the corresponding memory area is requested from the area release processing unit 16. In this case, the area release processing unit 16 executes the memory area release process in the same manner as described in FIG. 3. At the next step S26, it is determined whether the required memory area can be secured by releasing the area.

[0031] If it is determined that the processing of the request is possible (Yes in step S26), then at step S27, it waits until all of the areas instructed to be released are released, and then returns. After the return, the storage area requested in the shared storage 11 is secured. On the other hand, if the processing of the allocation request is not possible in step S26, that is, if it is determined that there is still a shortage of free areas even after the corresponding area has been released (No in step S26), then at step S28, the next storage area with a higher priority is extracted as the next area to be released, and the process returns to step S24, and the processing from step S24 is repeated.

[0032] On the other hand, if in step S24, the extracted area to be released is the area that has newly received an allocation request (No in step S24), then at the next step S29, the processing is suspended until the free capacity of the shared storage 11 becomes equal to or greater than the requested amount. That is, it waits until the use of the shared storage 11 by the current respective applications 7, 8, 9 ends and a free area greater than or equal to the requested amount is generated, and then returns. After the return, similarly, the storage area requested in the shared storage 11 is secured.

[0033] According to such a shared storage management apparatus and a shared storage management method of the present embodiment, the following operations and effects can be obtained. That is, the storage management unit 10 adjusts the securing and releasing of the storage areas of the shared storage 11 according to the requests of the respective applications 7, 8, 9. At this time, the storage management unit 10 sets a release priority for each storage area secured in the shared storage 11. Here, for example, if the use of the shared storage 11 concentrates among a plurality of applications 7, 8, 9, there may be a case where when there is a request for securing from another application 7, 8, 9, there is a possibility that the storage area to be secured in the shared storage 11 is insufficient. At this time, the storage management unit 10 instructs the release in order from the storage area with the highest release priority.

[0034] As a result, without waiting for the data in the existing storage areas of the shared storage 11 to be deleted by the applications 7, 8, and 9, the storage management unit 10 sequentially releases the storage areas with high release priorities, and in response to the requests of the applications 7, 8, and 9, the storage areas can be quickly released to secure the necessary storage areas. As a result, in the in-vehicle system 1 including the shared storage 11 shared by the plurality of applications 7, 8, and 9, an excellent effect of enabling efficient use of the storage areas of the shared storage 11 can be obtained.

[0035] Particularly in this embodiment, in the storage management unit 10, a configuration is adopted in which the static release priority is set based on at least one of the nature of the data used by the applications 7, 8, and 9 and the required capacity for securing the data area. As a result, in terms of the nature of the data, for example, whether it is an upload or a download, for those with relatively low importance, such as downloads, the priority can be increased, leaving the more important ones and releasing the others in order. Also, depending on whether the required capacity for securing the data area, that is, whether it exceeds a predetermined capacity, for example, 200 MB or not, for the larger ones, by increasing the priority, the effect of release becomes higher, and a larger capacity can be secured.

[0036] (2) Second Embodiment, Other Embodiments Next, referring to FIGS. 5 to 7, the second embodiment will be described. In this second embodiment, the process of securing the storage areas of the shared storage 1 executed by the storage management unit 10 is different from that of the first embodiment described above. In this embodiment, when there are a plurality of area securing requests for which area securing processing has not been performed, the storage management unit 10 sets a securing priority for these area securing requests and executes the securing processing in order from the one with the highest securing priority.

[0037] The flowchart of FIG. 5 shows the procedure for securing a storage area executed by the storage management unit 10, and the flowchart of FIG. 6 shows the detailed procedure for determining the securing priority in step S34 of FIG. 5. First, in FIG. 5, in step S31, when a request for securing a storage area is received from applications 7, 8, and 9, in step S32, it is determined whether there are other area securing requests waiting to be processed. If there are no other area securing requests (No in step S32), in the next step S33, the area securing request is set as the processing target and the process proceeds to step S36.

[0038] On the other hand, if it is determined in step S32 that there are other area securing requests (Yes in step S32), in the next step S34, a process for determining the securing priority for a plurality of area securing requests waiting to be processed is performed. The details of the process for determining the securing priority in this step S34 will be described later with reference to FIGS. 6 and 7. After the securing priority is determined, in the next step S35, the area securing request with the highest securing priority is determined as the processing target and the process proceeds to step S36. Steps S36 to S40 are the same as steps S2 to S6 in FIG. 2 of the first embodiment described above, so the description thereof is omitted.

[0039] Next, the flowchart of FIG. 6 shows the details of the process in step S34 of FIG. 5, that is, the process for determining the securing priority executed by the storage management unit 10. That is, in step S41, a request for determining the securing priority is received from the area securing processing unit 14, and the priority determination unit 17 receives the determination request. In the next step S42, the priority determination unit 17 acquires the content of the area securing request and the current state of the shared storage 11, that is, the data on the free capacity. In this embodiment, the content of the area securing request includes the order of the request, the area securing request capacity, and the nature of the data, that is, whether it is an upload or a download. Then, in step S43, the securing priority of each area securing request is calculated and returned.

[0040] Here, a specific example of calculating the securing priority executed in step S43 will be described with reference to FIG. 7. When calculating the securing priority, a plurality of n conditions X1, X2, …, Xn are quantified, and with respect to them, while weighting A1, A2, …, An, the priority is calculated using the following function. Priority Y1 = A1X1 + A2X2 + … + AnXn …(1)

[0041] Specifically, for example, n = 3 X1 = (Number of area securing requests waiting for processing - Request order) / (Number of area securing requests waiting for processing) X2 = 1 - (Requested amount / Free capacity of shared storage) X3 = Nature of data, for example, 1 for upload and 0 for download A1 = 2 / 4 A2 = 1 / 4 A3 = 1 / 4 The higher the value of the priority Y1, the higher the securing priority.

[0042] FIG. 7 shows calculation examples of the priority Y for three area securing requests when the free capacity of the shared storage 11 is 40MB and when it is 150MB. When the free capacity is 40MB, the priority of the securing request with the third request order is the highest. On the other hand, when the free capacity is 150MB, the priority of the securing request with the first request order is the highest. However, the above conditions, numerical values of weighting, etc. are merely examples, and it is necessary to appropriately determine them according to actual use. For example, as the nature of the data, for the case of download, the priority, that is, the value of X can be made larger than the case of upload.

[0043] According to such a second embodiment, in addition to obtaining the same operations and effects as those of the first embodiment, when there are a plurality of area reservation requests for which area reservation processing has not been performed, the storage management unit 10 can determine the reservation priority and execute the processing for reserving the storage area of the shared storage 11 in order. Since the order of requests, the area reservation request capacity, the nature of the data, and the free capacity of the current shared storage are used as conditions for obtaining the reservation priority, the reservation priority can be determined more appropriately.

[0044] In addition, in the first embodiment, the release priority is statically set based on at least one of the nature of the data to be used and the area reservation request capacity of the data. In contrast, it may be configured to determine the area to be released by combining the static release priority and a dynamic condition including at least one of the request order and the free capacity of the current shared storage. For example, as shown in Equation (1), each condition, that is, the static release priority, the request order, and the free capacity of the current shared storage are quantified, and the release priority may be calculated by weighting and calculating them. According to this, the release priority can be determined more precisely and appropriately.

[0045] Also, in the above embodiment, among the ECUs constituting the in-vehicle system 1, the shared storage 11 is provided in the ECU2 for the central gateway, and the functions of the storage management unit 10 are provided. However, it is also possible to provide these functions in another ECU. In the above embodiment, the present invention is applied to the in-vehicle system 1 in which a plurality of ECUs are network-connected. However, it can be applied to various types of systems having one or more computers in a closed network.

[0046] In addition, it goes without saying that formulas, conditions, specific numerical values, etc. for calculating the securing priority and the release priority can also be appropriately changed and implemented. Although the present disclosure has been described based on embodiments, it is understood that the present disclosure is not limited to such embodiments and structures. The present disclosure also includes various modifications and modifications within the equivalent scope. In addition, various combinations and forms, and further other combinations and forms including only one element, more than one element, or less than one element thereof, are within the scope and spirit of the present disclosure.

Description of Reference Numerals

[0047] In the drawings, 1 denotes an in-vehicle system (system), 2 denotes an ECU (computer, shared storage management device), 3 and 4 denote ECUs (computers), 5 denotes a network, 6 denotes an in-vehicle communication device, 7, 8, and 9 denote applications, 10 denotes a storage management unit, 11 denotes a shared storage, 12 denotes a storage management table, 13 denotes a request reception unit, 14 denotes an area securing processing unit, 15 denotes an area management unit, 16 denotes an area release processing unit, and 17 denotes a priority determination unit.

Claims

1. A system (1) provided in a closed network (5) including one or more computers (2, 3, 4) having a communication function with the outside, wherein a plurality of applications (7, 8, 9) on each computer exchange information with each other, and having a shared storage (11) used by the plurality of applications for writing and reading data, comprising a storage management unit (10) that adjusts securing and releasing of storage areas of the shared storage according to requests of the respective applications, the storage management unit sets a release priority for each storage area secured in the shared storage, when there is a request for securing from the application, if there is insufficient storage area to be secured in the shared storage, it instructs release in order from the storage area with the highest release priority, when there are a plurality of area securing requests for which securing of the storage area has not been performed, it sets the securing priority of those area securing requests based on conditions including at least one of the area securing request capacity, the request order, the nature of the data, and the current free capacity of the shared storage, and in this setting, considering the ratio of the area securing request capacity to the free capacity, a shared storage management device that executes securing processing in order from the one with the highest securing priority.

2. The shared storage management device according to claim 1, wherein the storage management unit sets a static release priority as the release priority based on at least one of the nature of the data used by the application and the area securing request capacity of the data.

3. The shared storage management device according to claim 1 or 2, wherein the storage management unit combines the release priority with a dynamic condition including at least one of the request order and the current free capacity of the shared storage to determine an area to be instructed for release.

4. A system (1) is provided in a closed network (5) and includes one or more computers (2, 3, 4) having a communication function with the outside. A plurality of applications (7, 8, 9) on each computer exchange information with each other and have a shared storage (11) used for writing and reading data. It includes a storage management unit (10) that adjusts the allocation and release of storage areas in the shared storage according to the requests of each application. The storage management unit sets a release priority for each storage area secured in the shared storage. When there is a request for allocation from the application and there is insufficient storage area to be allocated in the shared storage, it instructs the release of storage areas in order from the one with the highest release priority. When there are multiple requests for allocating areas where no storage area has been allocated, it sets the allocation priorities of these requests based on conditions including the order of requests, the capacity of the area allocation requests, the nature of the data, and the current free capacity of the shared storage. In this setting, considering the ratio of the capacity of the area allocation request to the free capacity, a shared storage management device that executes the allocation process in order from the one with the highest allocation priority.

5. In a system (1) in a closed network (5) that includes one or more computers (2, 3, 4) having a communication function with the outside, a plurality of applications (7, 8, 9) on each computer exchange information with each other, and the plurality of applications have a shared storage (11) used for writing and reading data. A method for adjusting the allocation and release of storage areas in the shared storage according to the requests of each application, wherein for each storage area secured in the shared storage, a release priority is set, and when there is a request for allocation from the application and there is insufficient storage area to be allocated in the shared storage, it instructs the release of storage areas in order from the one with the highest release priority. When there are multiple requests for securing areas where the memory area has not been secured, set the securing priorities of these area securing requests based on conditions including one or more of the area securing request capacity, request order, nature of data, and current free capacity of the shared storage. In this setting, consider the ratio of the area securing request capacity to the free capacity, and a shared storage management method that executes the securing process in order from the one with the highest securing priority.

6. A system (1) comprising an in-vehicle network (5) and a plurality of electronic control units (2, 3, 4) connected to the in-vehicle network, each of the electronic control units executing one or more applications (7, 8, 9), and having a shared storage (11) used by the one or more applications for writing and reading data. It is provided with a storage management unit (10) that adjusts the securing and release of the memory area of the shared storage according to the requests of each application. The storage management unit sets a release priority indicating the order of releasing each memory area for each memory area secured in the shared storage. When there is a request for securing from the application and there is a shortage of the memory area to be secured in the shared storage, the storage management unit instructs the release in order from the memory area with the highest release priority. When there are multiple requests for securing areas where the memory area has not been secured, set the securing priorities of these area securing requests based on conditions including one or more of the area securing request capacity, request order, nature of data, and current free capacity of the shared storage. In this setting, consider the ratio of the area securing request capacity to the free capacity, and a shared storage management device that executes the securing process in order from the one with the highest securing priority.

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