Control device, control method, program

Abstract

The present invention provides a control device that can reduce the delay in accessing the storage medium. [Solution] An access request to the storage medium is obtained from a higher level. In a faulty area storage means that stores the smallest storage area units of the storage medium that have been identified as faulty, if the access area of ​​the storage medium indicated by the access request includes the smallest storage area unit that has been identified as faulty, a determination result indicating that the smallest storage area unit has been identified as faulty is returned to the higher level before accessing the said smallest storage area unit.

Description

Technical Field

[0001] The present disclosure relates to a control device, a control method, and a program.

Background Art

[0002] In a computer device, it is required to speed up data reading and writing to a storage device such as a HDD (Hard Disk Drive).

[0003] For example, Patent Document 1 discloses a technology that addresses the problems of response delay of a storage medium represented by an SSD (Solid State Drive), elimination and avoidance of a temporary response stop state, in maintaining the reliability and stability of an information processing system. In Patent Document 1, a command queue that temporarily holds an access command obtained by converting an access request from a host into an access to a storage device, and a first means for determining whether to prohibit writing to the storage device based on the analysis result of the access command held in the command queue, and a second means for returning an error response to the access request from the host when writing is prohibited, are disclosed as a technology of a storage device.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the above-described technology, there is a need for a technology that can further reduce the delay in accessing a storage medium.

[0006] An object of the present disclosure is to provide a control device, a control method, and a program that solve the above problems.

Means for Solving the Problems

[0007] A control device according to one aspect of the present disclosure includes access request acquisition means for acquiring an access request to a storage medium from a higher level, and a faulty area storage means for storing a minimum storage area unit of the storage medium that has been identified as faulty, and when the minimum storage area unit corresponding to the access area of ​​the storage medium indicated by the access request is included, a return means for returning a determination result to the higher level indicating that the minimum storage area unit has been determined to be faulty before accessing the minimum storage area unit.

[0008] A control method according to one aspect of the present disclosure obtains an access request to a storage medium from a higher level, and in a faulty area storage means that stores a minimum storage area unit of the storage medium that has been identified as faulty, if the access request includes a minimum storage area unit corresponding to the access area of ​​the storage medium indicated by the access request, it returns a determination result to the higher level indicating that it has been determined to be faulty before accessing the minimum storage area unit.

[0009] A program according to one aspect of this disclosure causes a computer to function as an access request acquisition means for acquiring an access request to a storage medium from a higher level, and a faulty area storage means for storing a minimum storage area unit of the storage medium that has been identified as faulty, and which, when the access request includes a minimum storage area unit corresponding to the access area of ​​the storage medium indicated by the access request, returns a determination result to the higher level indicating that the minimum storage area unit has been determined to be faulty before accessing the minimum storage area unit. [Effects of the Invention]

[0010] According to the above embodiment, the delay in accessing the storage medium can be reduced. [Brief explanation of the drawing]

[0011] [Figure 1] This figure shows the hardware configuration of a computer equipped with a storage device that includes the functions of a control device according to one aspect of the present disclosure. [Figure 2]This figure shows another hardware configuration of a computer according to one aspect of the present disclosure. [Figure 3] A functional block diagram of a device control unit according to one aspect of this disclosure is shown. [Figure 4] This figure shows a computer processing flow according to one aspect of the present disclosure. [Figure 5] This disclosure provides an overview of the related computer processing according to one aspect of this disclosure. [Figure 6] This figure shows a functional block of another configuration of a control device according to one aspect of the present disclosure. [Figure 7] This figure shows the processing flow of another configuration of the control device according to one aspect of the present disclosure. [Modes for carrying out the invention]

[0012] Figure 1 shows the hardware configuration of a computer equipped with a storage device including the functions of a control device according to one aspect of the present disclosure. As shown in Figure 1, the computer 10 comprises a CPU (Central Processing Unit) 1, a DAC (Disk Array Controller) 2, and a storage device 3. The storage device 3 is a physical drive (PD), such as an HDD (Hard Disk Drive) or SSD (Solid State Drive). The CPU 1 is connected to the DAC 2, and the DAC 2 is connected to the storage device 3. The CPU 1 and DAC 2, and the DAC 2 and storage device 3, are connected to each other via signal lines to send and receive control signals.

[0013] CPU1 controls computer 10. DAC2 controls the memory device 3. The storage device 3 includes an error table 31 (bad area storage means), an immediate error return register 32 (operating condition storage means), a device control unit 33, and a storage medium 34.

[0014] In the storage device 3, the error table 31 is a data table that stores the locations of sectors identified as faulty among the smallest storage area units of the storage medium 34. For example, the error table 31 may store the location and identification information of the faulty sectors. The immediate error return register 32 stores an operating condition indicating whether to determine whether the access area contains sectors identified as bad before accessing the access area based on the access request. The operating condition is recorded in the immediate error return register 32 as a flag, for example. If the flag is 1, it is determined whether the access area contains sectors identified as bad. The storage medium 34 is the medium on which data is written.

[0015] In the computer 10 of this disclosure, the device control unit 33, which is an example of a control device included in the storage device 3, receives an access request to the storage medium from a higher level and stores the location of a sector of the storage medium 34 that has been identified as defective in an error table 31. If the error table 31, which stores the sectors of the storage medium 34 that have been identified as defective, contains a sector corresponding to the access area of ​​the storage medium 34 indicated by the access request, the device control unit 33 returns a determination result to the higher level indicating that the sector has been determined to be defective before accessing that sector. The error table 31 may also contain information on the location and identification of sectors that the device control unit 33 has previously detected. Sector defects occur, for example, due to the deterioration of magnetic material, and the device control unit 33 can detect and identify the location of the sector defects using known techniques.

[0016] The device control unit 33 checks the operating conditions indicated by the flags stored in the immediate error return register 32. When the operating conditions indicate that it is necessary to determine whether the access area contains sectors identified as defective before accessing the access area, the device control unit 33 determines whether the access area contains sectors identified as defective before accessing the access area. When the operating conditions indicated by the flags stored in the immediate error return register 32 do not indicate that it is necessary to determine whether the access area contains sectors identified as defective before accessing the access area, the device control unit 33 performs control to access the access area corresponding to the access request without making such a determination. When the access area indicated by the access request does not contain sectors identified as defective, the device control unit 33 immediately performs control to access the access area corresponding to the access request. Note that the access to the access area may be a read (read) of data from the access area indicated by the access request or a write of data to the access area indicated by the access request.

[0017] FIG. 2 is a diagram showing another hardware configuration of a computer according to an aspect of the present disclosure. In addition to the CPU 1, DAC 2, and storage device 3 shown in FIG. 1, the computer 10 may include a ROM 4, a RAM 5, a communication module 6, etc., as shown in FIG. 2.

[0018] FIG. 3 is a functional block diagram of the device control unit according to an aspect of the present disclosure. The device control unit 33 exhibits the functions of the control processing unit 35, the access request acquisition unit 36, the determination unit 37, and the return unit 38 by means of a circuit or by executing a program. The control processing unit 35 controls the storage device 3. The access request acquisition unit 36 acquires an access request to the storage medium 34 from a higher level such as the DAC 2. If the operation condition indicated by the flag stored in the immediate error return register 32 indicates that a determination should be made whether the access area contains sectors identified as bad before accessing the access area, the determination unit 37 refers to the error table 31 before accessing the access area to determine whether the access area contains sectors identified as bad. The return unit 38, by referring to the error table 31, determines that the access area of ​​the storage medium 34 indicated by the access request contains a sector identified as defective. In this case, before accessing the sector, it returns a determination result to the higher-level DAC2 indicating that the sector has been determined to be defective.

[0019] The device control unit 33, equipped with these functional units, receives access requests to the storage medium 34 from a higher level and stores sectors of the storage medium 34 that have been identified as faulty in the error table 31. If the access area of ​​the storage medium 34 indicated by the access request contains a sector identified as faulty, the device control unit 33 returns a determination result to the higher level indicating that the sector has been determined to be faulty before accessing that sector. This reduces the time-consuming retry process that would occur due to unnecessary access to faulty sectors of the storage medium 34, thereby reducing the delay in accessing the storage medium.

[0020] Figure 4 shows a computer processing flow according to one aspect of this disclosure. Next, we will explain the computer's processing flow step by step.

[0021] When the computer 10 is powered on, the device control unit 33 rewrites the flag in the immediate error return register 32 to ON (step S101). Alternatively, the user may pre-record a setting file in the storage device 3 indicating whether the flag in the immediate error return register 32 is ON or OFF, and the device control unit 33 may read the flag described in that setting file and rewrite the ON or OFF state of the flag in the immediate error return register 32 to the same value. When the flag in the immediate error return register 32 is ON, the device control unit 33 of the storage device 3, if the access area of ​​the storage medium 34 indicated by the access request contains a sector identified as defective, performs control to return a determination result indicating that the sector has been determined to be defective to a higher level before accessing the sector.

[0022] In this state, CPU1 outputs an access request to DAC2 as part of the OS (Operating System) operation (step S102). This access request may be a Read request. If this access request is a Read request, the request includes the range of the sector to be accessed in the storage medium 34. DAC2 receives the access request. DAC2 outputs the access request to the storage device 3 (step S103). In the storage device 3, the access request acquisition unit 36 ​​of the device control unit 33 receives the access request (step S104). When the access request acquisition unit 36 ​​receives the access request, the control processing unit 35 reads the flag recorded in the immediate error return register.

[0023] The control processing unit 35 determines whether the flag recorded in the immediate error return register is ON (step S105). If the flag recorded in the immediate error return register is ON, the control processing unit 35 instructs the determination unit 37 to start the determination process. The determination unit 37 obtains the sector range and sector identifier included in the access request from the access request acquisition unit 36. The determination unit 37 determines whether the sector range and sector identifier included in the access request are recorded in the error table 31 (step S106).

[0024] The determination unit 37 instructs the return unit 38 to return the data if the sector range or sector identifier included in the access request is recorded in the error table 31. When the return unit 38 receives the return instruction, it does not perform a read operation on the storage medium 34 based on the access request, but instead sends a media error to the DAC2 indicating that the sector included in the access request acquired by the access request acquisition unit 36 ​​is an error (step S107).

[0025] Through this process, if the sector range or sector identifier included in the access request is recorded in the error table 31, the access process for that sector is not performed, and a media error is immediately sent to the DAC2. Therefore, retry processing is not performed in the access process (such as reading the sector) for the sector where the error occurred. Consequently, the operation time of the retry process in the storage device 3 can be reduced.

[0026] DAC2 acquires media errors. Media errors may include the sector range and identifier indicated by the access request. DAC2 performs media error processing (step S108). Media error processing, if the storage device 3 is configured in a RAID and has redundancy, involves supplementing information from the parity PD, writing back normal data, and repairing the media error. If the storage device is not configured in a RAID and does not have redundancy, the media error processing differs depending on the type of DAC2, but for example, it may involve recording the media error in the bad block table and leaving the media error as is.

[0027] When DAC2 processes a media error, it determines whether it has received an access request (such as a Read request) from CPU1 or if the request has been completed (step S109). If DAC2 determines that the access request has not been completed, it sends the next access request received from CPU1 to the storage device 3 (returning to step S103). In the storage device 3, the access request acquisition unit 36 ​​of the device control unit 33 acquires the access request, and the process from step S104 onwards is repeated. This process corresponds to the device control unit 33, after completing the repair process for the sector determined to be defective (media error processing), determining whether the access request has been completed, and if the operating conditions indicate that the determination should be made before accessing the access area, repeating the process of determining whether the access area of ​​the storage medium 34 indicated by the access request contains the sector that was identified as defective, based on the subsequent access request, before accessing the access area. If DAC2 determines that the access request has been completed, it terminates the process (step S110). DAC2 waits to acquire the next access request from CPU1.

[0028] In the process of step S105 described above, if the flag recorded in the immediate error return register is OFF, or in the process of step S106, if the flag recorded in the immediate error return register is ON, but the determination unit 37 determines that the sector range or sector identifier included in the access request is not recorded in the error table 31, the control processing unit 35 performs access processing (Read processing) to the sector based on the access request (step S111). The control processing unit 35 determines whether the access processing was successful or not (step S112). If the access processing is successful, the control processing unit 35 terminates processing and waits to receive the next access request.

[0029] If the access processing fails, the control processing unit 35 performs a retry process for the sector range or each sector indicated by the access request that failed (step S113). If the access request is a Read request, the retry process involves reading again from the sector indicated by that access request. This re-reading process takes time. The control processing unit 35 determines whether the retry process failed (step S114). If the retry process fails, the control processing unit 35 instructs the return unit 38 to return the data. If the return unit 38 receives the return instruction, it performs the process in step S107, which involves sending a media error to the DAC2 indicating that the sector included in the access request acquired by the access request acquisition unit 36 ​​is an error. If the retry process is successful in step S115, the control processing unit 35 terminates processing and waits to acquire the next access request. The above access request may also be a Write request.

[0030] Figure 5 shows an overview of the related computer processing according to one aspect of this disclosure. Figures 5(a), (b), and (c) show sector ranges and the states of each sector within those ranges, respectively. Assume the sector range included in the access request is s1 to sN. Also assume that among the sectors in the sector range s1 to sN, sectors s10 to sN are media errors. When the associated computer receives the access request (step S21), it performs access processing (e.g., Read processing) sequentially from sector s1 to sN within the sector range included in the access request, and detects a Read failure (error detection) at sector s10 due to a media error (step S22). In this case, if the control processing unit of the storage device fails the access processing, it performs retry processing for the sector range or each sector that failed the access processing indicated in the access request (step S23). This retry processing takes several seconds. If the control processing unit of the storage device determines that Read is not possible as a result of the retry processing, it sends a media error to DAC2 (step S24). Subsequently, DAC2 performs media error processing in the same manner as above (step S25). The control unit of the memory device then repeats the same process for each sector s11 to sN that is experiencing a media error, as shown in Figures 5(b) and (c). This results in a significant amount of time being required for the access processing of the sector range indicated by the access request to be completed.

[0031] On the other hand, according to the processing in steps S101 to S115 described above, an access request to the storage medium is received from a higher level, sectors of the storage medium that have been identified as faulty are stored in advance, and if the access area of ​​the storage medium indicated by the access request includes sectors that have been identified as faulty, a determination result indicating that the sector has been determined to be faulty is immediately returned to the higher level before performing the access processing to the sector. As a result, the DAC2 immediately processes the media error and finishes processing the media error for each sector in the sector range indicated by the access request. This reduces the processing in the storage device 3 and reduces the delay in accessing the storage medium.

[0032] Figure 6 shows a functional block of another configuration of a control device according to one aspect of the present disclosure. Figure 7 shows the processing flow of another configuration of a control device according to one aspect of the present disclosure. The control device 60, corresponding to the device control unit 33 in Figure 1, comprises at least an access request acquisition means 61 and a return means 62. The access request acquisition means 61 acquires an access request to the storage medium from a higher level (step S601). The return means 62, in the defective area storage means that stores the smallest storage area units of the storage medium that have been identified as defective, returns a determination result indicating that the smallest storage area unit is defective to a higher level before accessing the access area of ​​the storage medium indicated by the access request, if the defective area storage means includes the smallest storage area unit that has been identified as defective (step S602).

[0033] Although the present disclosure has been described above with reference to embodiments, the present disclosure is not limited to the embodiments described above. Various modifications to the structure and details of the present disclosure may be made that can be understood by those skilled in the art within the scope of the present disclosure.

[0034] Some or all of the above embodiments may also be described as follows, but are not limited to the following:

[0035] (Note 1) An access request acquisition means for acquiring an access request to a storage medium from a higher level, In a defective area storage means that stores a minimum storage area unit of the storage medium that has been identified as defective, if the access request includes a minimum storage area unit corresponding to the access area of ​​the storage medium, the return means returns a determination result indicating that the minimum storage area unit has been determined to be defective to the higher level before accessing the said minimum storage area unit. A control device equipped with the following features.

[0036] (Note 2) In an operating condition storage means that stores an operating condition indicating whether to perform the determination before accessing the access area, if the operating condition indicates that the determination should be performed before accessing the access area, the determination means determines whether the access area of ​​the storage medium indicated by the access request contains the smallest storage area unit identified as defective, before accessing the access area. The control device described in Appendix 1, comprising:

[0037] (Note 3) If the aforementioned operating conditions do not indicate that the determination is made before accessing the access area, the control means performs control to access the access area in response to the access request without making the determination, The control device described in Appendix 2, which includes the following:

[0038] (Note 4) The control means, if the access area indicated by the access request does not include the minimum storage area unit identified as defective, performs control to access the access area corresponding to the access request. The control device described in Appendix 3.

[0039] (Note 5) A control device according to any one of the appendices 1 to 4, provided in a storage device equipped with the aforementioned storage medium.

[0040] (Note 6) The aforementioned higher-level device is a controller that controls multiple storage devices. The control device described in Appendix 5.

[0041] (Note 7) The minimum storage area unit is a sector provided in the storage medium. A control device as described in any one of the appendices 1 through 6.

[0042] (Note 8) If the control means does not determine that the access request has been completed after the repair process of the minimum storage area unit determined to be defective has been completed, and the operating condition indicates that the determination should be made before accessing the access area, then, based on a subsequent access request, the control means repeats the process of determining whether the access area of ​​the storage medium indicated by the access request contains the minimum storage area unit identified as defective, before accessing the access area. The control device described in Appendix 3 or Appendix 4.

[0043] (Note 9) Obtain an access request to the storage medium from a higher level, In a defective area storage means that stores a minimum storage area unit of the storage medium that has been identified as defective, if the access request includes a minimum storage area unit corresponding to the access area of ​​the storage medium indicated by the access request, the means returns a determination result indicating that the minimum storage area unit has been determined to be defective to the higher level before accessing the said minimum storage area unit. Control method.

[0044] (Note 10) In an operating condition storage means that stores an operating condition indicating whether to perform the determination before accessing the access area, if the operating condition indicates that the determination should be performed before accessing the access area, it is determined whether the access area of ​​the storage medium indicated by the access request contains the smallest storage area unit identified as defective, before accessing the access area. The control method described in Appendix 9.

[0045] (Note 11) If the aforementioned operating conditions do not indicate that the determination is made before accessing the access area, the control is performed to access the access area in response to the access request without making the determination. The control method described in Appendix 10.

[0046] (Note 12) If the access area indicated by the access request does not include the smallest storage area unit identified as defective, control is performed to access the access area corresponding to the access request. The control method described in Appendix 11.

[0047] (Note 13) A control method according to any one of the appendices 9 to 12, performed by a control means for a storage device equipped with the aforementioned storage medium.

[0048] (Note 14) The aforementioned higher-level device is a controller that controls multiple storage devices. The control method described in Appendix 13.

[0049] (Note 15) The minimum storage area unit is a sector provided in the storage medium. The control method described in any one of the appendices 9 through 14.

[0050] (Note 16) If, after the completion of the repair process for the minimum storage area unit determined to be defective, the access request is not determined to be completed, and the operating condition indicates that the determination should be made before accessing the access area, then, based on a subsequent access request, the process of determining whether the access area of ​​the storage medium indicated by the access request contains the minimum storage area unit identified as defective is repeated before accessing the access area. The control method described in any one of the appendices 10 to 12.

[0051] (Note 17) Computers, Access request acquisition means for acquiring access requests to storage media from a higher level. In a defective area storage means that stores a minimum storage area unit of the storage medium that has been identified as defective, if the access request includes a minimum storage area unit corresponding to the access area of ​​the storage medium indicated by the access request, a return means that returns a determination result indicating that the minimum storage area unit has been determined to be defective to the higher level before accessing the said minimum storage area unit. A program that makes it function as such.

[0052] (Note 18) In an operating condition storage means that stores an operating condition indicating whether to perform the determination before accessing the access area, if the operating condition indicates that the determination should be performed before accessing the access area, the determination means determines whether the access area of ​​the storage medium indicated by the access request contains the smallest storage area unit identified as defective, before accessing the access area. The program described in Appendix 17 is used to make it function as follows.

[0053] (Note 19) If the aforementioned operating conditions do not indicate that the determination is made before accessing the access area, the control means performs control to access the access area in response to the access request without making the determination. The program described in Appendix 18 is used to make it function as follows.

[0054] (Note 20) The control means, if the access area indicated by the access request does not include the minimum storage area unit identified as defective, performs control to access the access area corresponding to the access request. The program described in Appendix 19.

[0055] (Note 21) The program described in Appendix 19 or Appendix 20 is executed by the control means of the storage device equipped with the storage medium.

[0056] (Note 22) The aforementioned higher-level device is a controller that controls multiple storage devices. The program described in Appendix 21.

[0057] (Note 23) The minimum storage area unit is a sector provided in the storage medium. The program described in any one of the appendices 17 through 22.

[0058] (Note 24) If the control means does not determine that the access request has been completed after the repair process of the minimum storage area unit determined to be defective has been completed, and the operating condition indicates that the determination should be made before accessing the access area, then, based on a subsequent access request, the control means repeats the process of determining whether the access area of ​​the storage medium indicated by the access request contains the minimum storage area unit identified as defective, before accessing the access area. The program described in any one of the appendices 19 to 21. [Explanation of Symbols]

[0059] 1..CPU 2..DAC 3...Storage device 31. Error Table 32...Immediate Error Return Register 33. Device Control Unit 34...Storage medium 35. Control Processing Unit 36. Access Request Acquisition Unit 37... Judgment section 38...Returns Department

Claims

1. An access request acquisition means for acquiring an access request to a storage medium from a higher level, In a defective area storage means that stores a minimum storage area unit of the storage medium that has been identified as defective, if the access request includes a minimum storage area unit corresponding to the access area of ​​the storage medium, the return means returns a determination result indicating that the minimum storage area unit has been determined to be defective to the higher level before accessing the said minimum storage area unit. A control device equipped with the following features.

2. In an operating condition storage means that stores an operating condition indicating whether to perform the determination before accessing the access area, if the operating condition indicates that the determination should be performed before accessing the access area, the determination means determines whether the access area of ​​the storage medium indicated by the access request contains the smallest storage area unit identified as defective, before accessing the access area. The control device according to claim 1, comprising:

3. If the aforementioned operating conditions do not indicate that the determination is made before accessing the access area, the control means performs control to access the access area in response to the access request without making the determination, The control device according to claim 2, comprising:

4. The control means, if the access area indicated by the access request does not include the minimum storage area unit identified as defective, performs control to access the access area corresponding to the access request. The control device according to claim 3.

5. The control device according to claim 4, provided in a storage device equipped with the aforementioned storage medium.

6. The aforementioned higher-level device is a controller that controls multiple storage devices. The control device according to claim 5.

7. The minimum storage area unit is a sector provided in the storage medium. The control device according to claim 6.

8. If, after the completion of the repair process for the minimum storage area unit determined to be defective, the access request is not determined to be completed, and the operating condition indicates that the determination should be made before accessing the access area, then, based on a subsequent access request, the process of determining whether the access area of ​​the storage medium indicated by the access request contains the minimum storage area unit identified as defective is repeated before accessing the access area. The control device according to claim 7.

9. Obtain an access request to the storage medium from a higher level, In a defective area storage means that stores a minimum storage area unit of the storage medium that has been identified as defective, if the access request includes a minimum storage area unit corresponding to the access area of ​​the storage medium indicated by the access request, the means returns a determination result indicating that the minimum storage area unit has been determined to be defective to the higher level before accessing the said minimum storage area unit. Control method.

10. Computers, Access request acquisition means for acquiring access requests to storage media from a higher level. In a defective area storage means that stores a minimum storage area unit of the storage medium that has been identified as defective, if the access request includes a minimum storage area unit corresponding to the access area of ​​the storage medium indicated by the access request, a return means that returns a determination result indicating that the minimum storage area unit has been determined to be defective to the higher level before accessing the said minimum storage area unit. A program that makes it function as such.

Images