Data recording device and method for controlling data recording device

Abstract

This data recording device (4) comprises: a non-volatile memory (14); a high-performance non-volatile memory (12) having a faster processing speed than the non-volatile memory (14); and an access control unit (10) that controls the writing of data to each of the non-volatile memory (14) and the high-performance non-volatile memory (12) on the basis of an index related to the temperature of the non-volatile memory (14). The access control unit (10): (a) writes the data to the non-volatile memory (14) when the index satisfies a first condition; and (b) writes the data to the high-performance non-volatile memory (12) and moves the data from the high-performance non-volatile memory (12) to the non-volatile memory (14) when the index satisfies a second condition.

Description

[Technical Field]

[0001] The present disclosure relates to a data recording device and a method for controlling a data recording device. [Background technology]

[0002] A data recording device equipped with a volatile memory and a nonvolatile memory is known (see, for example, Patent Document 1). In this type of data recording device, in order to reduce power consumption in the data recording device, data is first written to the volatile memory, which has a high processing speed, and then the data is moved from the volatile memory to the nonvolatile memory using a writing method that matches the recording characteristics of the nonvolatile memory. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-26388 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a data recording device and a method for controlling the data recording device that can prevent data loss. [Means for solving the problem]

[0005] The data recording device of the present disclosure comprises a first non-volatile memory, a second non-volatile memory having a faster processing speed than the first non-volatile memory, and an access control unit that controls writing of data to each of the first non-volatile memory and the second non-volatile memory based on an index related to the temperature of the first non-volatile memory, wherein the access control unit (a) writes data to the first non-volatile memory if the index satisfies a first condition, and (b) writes data to the second non-volatile memory and moves data from the second non-volatile memory to the first non-volatile memory if the index satisfies a second condition. [Effects of the Invention]

[0006] According to the data recording device and the like of the present disclosure, data loss can be avoided. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a block diagram showing the configuration of a data recording system according to the first embodiment. [Figure 2A] FIG. 2A is a flowchart showing the flow of a data writing process performed by the data recording device according to the first embodiment. [Figure 2B] FIG. 2B is a flowchart showing the flow of data transfer processing by the data recording device according to the first embodiment. [Figure 3] FIG. 3 is a block diagram showing the configuration of a data recording system according to a comparative example. [Figure 4] FIG. 4 is a flowchart showing the flow of data transfer processing by the data recording device according to the modification of the first embodiment. [Figure 5] FIG. 5 is a block diagram showing the configuration of a data recording system according to the second embodiment. [Figure 6] FIG. 6 is a flowchart showing the flow of operations of the data recording device according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] (Findings that formed the basis of this disclosure) The present inventors have found that the techniques described in the "Background Art" section have the following problems.

[0009] In the conventional data recording device described above, if the power supply to the data recording device is suddenly cut off, for example due to a power outage, there is a problem in that data that has not been moved from the volatile memory to the non-volatile memory is lost.

[0010] Therefore, the present inventors have conducted extensive research and have devised a data recording device and a method for controlling the data recording device that can prevent data loss.

[0011] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, more detailed explanation than necessary may be omitted. For example, detailed explanation of well-known matters or redundant explanation of substantially the same configuration may be omitted. This is to avoid unnecessary redundancy in the following explanation and to facilitate understanding by those skilled in the art.

[0012] The inventors have provided the accompanying drawings and the following description to enable those skilled in the art to fully understand the present disclosure, and do not intend for them to limit the subject matter described in the claims.

[0013] (Embodiment 1) [1-1. Data recording system configuration] First, the configuration of a data recording system 2 according to the first embodiment will be described with reference to Fig. 1. Fig. 1 is a block diagram showing the configuration of a data recording system 2 according to the first embodiment.

[0014] 1, a data recording system 2 according to the first embodiment includes a data recording device 4 and a host device 6. The data recording device 4 and the host device 6 are connected to each other so as to be able to communicate with each other via a network 8. The network 8 is configured using, for example, Ethernet (registered trademark) or the like.

[0015] The data recording device 4 is a storage unit for recording various data. The data recording device 4 includes an access control unit 10, a high-performance nonvolatile memory 12 (an example of a second nonvolatile memory), a nonvolatile memory 14 (an example of a first nonvolatile memory), and a temperature sensor 16.

[0016] The data recording device 4 has a memory such as a ROM (Read Only Memory) or a RAM (Random Access Memory) for recording the software program, a CPU (Central Processing Unit) for reading and executing the software program recorded in the memory, a communication interface for communicating with the host device 6 via the network 8, and storage for recording various data. The access control unit 10 is realized by the CPU reading and executing the software program recorded in the memory.

[0017] The data recording device 4 is accessed from the host device 6 via the network 8 using a protocol for storage installed in the data recording device 4, such as NVMe-oF (Non-Volatile Memory express-over Fabrics). Inside the data recording device 4, the data recording device 4 is accessed using a protocol for storage installed in the data recording device 4, such as NVMe.

[0018] The access control unit 10 is a communication interface that receives data from the host device 6. When the access control unit 10 receives data from the host device 6, it controls the writing of the data to each of the high-performance nonvolatile memory 12 and the nonvolatile memory 14 based on the temperature detected by the temperature sensor 16. Specifically, the access control unit 10 selects either the high-performance nonvolatile memory 12 or the nonvolatile memory 14 as the write destination of the data from the host device 6 based on the temperature detected by the temperature sensor 16.

[0019] The high-performance nonvolatile memory 12 is a nonvolatile memory with a faster processing speed than the nonvolatile memory 14, and is a storage device configured, for example, with an Intel Optane SSD (Solid State Drive) (registered trademark). In this high-performance nonvolatile memory 12, data is written and erased in byte units. The high-performance nonvolatile memory 12 generates more heat (power consumption) than a DRAM (Dynamic Random Access Memory) (volatile memory 108 shown in FIG. 3, which will be described later) used as a buffer memory in conventional technology. The high-performance nonvolatile memory 12 is also used as a buffer memory for temporarily recording data, and all data written to the high-performance nonvolatile memory 12 is eventually moved to the nonvolatile memory 14.

[0020] The nonvolatile memory 14 is a storage device configured with, for example, an SSD equipped with a NAND-type flash memory. In this nonvolatile memory 14, data is written in units of pages, and data is erased in units of blocks each including multiple pages. The storage capacity of the nonvolatile memory 14 is larger than the storage capacity of the high-performance nonvolatile memory 12.

[0021] The temperature sensor 16 detects the temperature of the nonvolatile memory 14 (an example of an index related to the temperature of the nonvolatile memory 14) and outputs the detection result to the access control unit 10.

[0022] The host device 6 is a device for processing data, such as a video editing device for processing video data. The host device 6 can write data to the storage (high-performance nonvolatile memory 12 or nonvolatile memory 14) installed in the data recording device 4 by accessing the data recording device 4 via the network 8.

[0023] [1-2. Operation of the data recording device] Next, a data writing process performed by the data recording device 4 according to the first embodiment will be described with reference to Fig. 2A. Fig. 2A is a flowchart showing the flow of the data writing process performed by the data recording device 4 according to the first embodiment.

[0024] The following describes a case where the host device 6 accesses the data recording device 4 via the network 8 and instructs the data recording device 4 to write data. Specifically, the host device 6 transmits data together with a recording command to the recording device 4 via the network 8. The recording command is a command signal that instructs the recording device 4 to write the data to the recording device 4. The recording command includes, for example, information indicating the size of the data.

[0025] When receiving data from the host device 6, the access control unit 10 acquires the temperature detected by the temperature sensor 16. As shown in Fig. 2A, the access control unit 10 determines whether the temperature of the nonvolatile memory 14 is higher than a predetermined temperature (e.g., 75°C) (an example of the first temperature and the second temperature) based on the temperature detected by the temperature sensor 16 (S101).

[0026] If the temperature of the nonvolatile memory 14 is equal to or lower than the predetermined temperature (i.e., if the index satisfies the first condition) (NO in S101), the access control unit 10 writes the data from the host device 6 to the nonvolatile memory 14 (S102). At this time, the access control unit 10 writes the data directly to the nonvolatile memory 14 without going through the high-performance nonvolatile memory 12. The access control unit 10 also writes the data in the size specified by the recording command without considering the blocks of the nonvolatile memory 14. The temperature rise of the nonvolatile memory 14 increases in proportion to the size of the data to be written. In other words, the smaller the write size per unit time in the nonvolatile memory 14, the less heat is generated in the nonvolatile memory 14.

[0027] When writing of all the data instructed by the host device 6 has been completed (YES in S103), the process ends. On the other hand, when writing of all the data instructed by the host device 6 has not been completed (NO in S103), the process returns to step S101 described above. In this case, repeatedly writing data to the nonvolatile memory 14 causes the temperature of the nonvolatile memory 14 to rise. Writing of data to the nonvolatile memory 14 (S102) is repeatedly executed until the temperature of the nonvolatile memory 14 rises and reaches a predetermined temperature.

[0028] In step S101, if the temperature of the nonvolatile memory 14 is higher than the predetermined temperature (i.e., if the index satisfies the second condition) (YES in S101), the access control unit 10 writes the data from the host device 6 to the high-performance nonvolatile memory 12 (S104). Note that as the temperature of the nonvolatile memory 14 rises above the predetermined temperature, the data recording speed in the nonvolatile memory 14 slows down due to the characteristics of the nonvolatile memory 14. More specifically, since the nonvolatile memory 14 may be destroyed if it becomes too hot, control is performed to reduce the amount of data written per unit time (heat generation) by, for example, lowering the operating clock so that the temperature of the nonvolatile memory 14 does not exceed a certain temperature. This delays the timing of the write completion notification to the host device 6, and as a result, the data recording speed as seen from the host device 6 slows down. Therefore, if the temperature of the nonvolatile memory 14 is higher than the predetermined temperature, the access control unit 10 switches the data writing destination from the nonvolatile memory 14 to the high-performance nonvolatile memory 12 to prevent a further rise in the temperature of the nonvolatile memory 14.

[0029] After step S104, if writing of all the data instructed by the host device 6 has been completed (YES in S103), the process ends. On the other hand, if writing of all the data instructed by the host device 6 has not been completed (NO in S103), the process returns to step S101 described above. In this case, writing of data to the advanced nonvolatile memory 12 (S104) is repeatedly executed until the temperature of the nonvolatile memory 14 drops and reaches a predetermined temperature. During this time, no data is written directly to the nonvolatile memory 14, so the temperature of the nonvolatile memory 14 gradually drops.

[0030] Next, the data transfer process performed by the data recording device 4 according to the first embodiment will be described with reference to Fig. 2B. Fig. 2B is a flowchart showing the flow of the data transfer process performed by the data recording device 4 according to the first embodiment.

[0031] As shown in FIG. 2B, when data from the host device 6 is written to the high-performance nonvolatile memory 12, the access control unit 10 determines whether the temperature of the nonvolatile memory 14 is higher than a predetermined temperature (e.g., 70°C) based on the temperature detected by the temperature sensor 16 (S201).

[0032] If the temperature of the nonvolatile memory 14 is higher than the predetermined temperature because the temperature has not dropped sufficiently (YES in S201), the access control unit 10 sets the transfer size per data transfer from the advanced nonvolatile memory 12 to the nonvolatile memory 14 to "small" (an example of a second size) (S202). The access control unit 10 transfers data from the advanced nonvolatile memory 12 to the nonvolatile memory 14 at the set transfer size "small" (S203). In this way, by setting the data transfer size to "small" when the temperature of the nonvolatile memory 14 is higher than the predetermined temperature, it is possible to prevent a further rise in the temperature of the nonvolatile memory 14 due to the data transfer.

[0033] On the other hand, in step S201, if the temperature of the nonvolatile memory 14 has dropped sufficiently and is equal to or lower than the predetermined temperature (NO in S201), the access control unit 10 sets the transfer size per data transfer from the advanced nonvolatile memory 12 to the nonvolatile memory 14 to "large" (an example of a first size) (S204). This "large" transfer size is larger than the "small" transfer size set in step S202. The access control unit 10 transfers data from the advanced nonvolatile memory 12 to the nonvolatile memory 14 at the set "large" transfer size (S203). In this way, when the temperature of the nonvolatile memory 14 is equal to or lower than the predetermined temperature, setting the data transfer size to "large" allows data to be transferred in a short time while maintaining the data recording speed in the nonvolatile memory 14.

[0034] Note that the above-mentioned "large" and "small" movement sizes are both integer multiples of the block size of the nonvolatile memory 14, and in step S203, data is moved in block units of the nonvolatile memory 14. Furthermore, writing data to the nonvolatile memory 14 via the high-performance nonvolatile memory 12 suppresses the temperature rise of the nonvolatile memory 14 compared to writing data directly to the nonvolatile memory 14. The reason for this is that when data is written to the nonvolatile memory 14 via the high-performance nonvolatile memory 12, data is written to the nonvolatile memory 14 in block units of an optimal size, which suppresses the occurrence of garbage collection and reduces the number of writes to the nonvolatile memory 14.

[0035] If data remains in the high-performance nonvolatile memory 12, that is, if all of the data written in the high-performance nonvolatile memory 12 has not been moved to the nonvolatile memory 14 (YES in S205), the process returns to step S201 described above. In this case, the processes in steps S201 to S205 described above are repeatedly executed until all of the data written in the high-performance nonvolatile memory 12 has been moved to the nonvolatile memory 14.

[0036] On the other hand, if there is no data remaining in the advanced nonvolatile memory 12, that is, if all of the data written in the advanced nonvolatile memory 12 has been moved to the nonvolatile memory 14 (NO in S205), the process ends.

[0037] [1-3.Effects] Fig. 3 is a block diagram showing the configuration of a data recording system 100 according to a comparative example. As shown in Fig. 3, the data recording system 100 according to the comparative example includes a data recording device 102 and a host device 104. The data recording device 102 and the host device 104 are connected to each other via a network 106 so as to be able to communicate with each other.

[0038] The data recording device 102 includes a volatile memory 108 and a nonvolatile memory 110. The volatile memory 108 is, for example, a DRAM, and the nonvolatile memory 110 is, for example, a NAND-type flash memory.

[0039] In this data recording device 102, in order to reduce power consumption in the data recording device 102, data is first written to a volatile memory 108, which has a high processing speed, and then the data is moved from the volatile memory 108 to the non-volatile memory 110 using a writing method that matches the recording characteristics of the non-volatile memory 110.

[0040] However, if the power supply to the data recording device 102 is suddenly cut off, for example due to a power outage, the data remaining in the volatile memory 108 will be lost without being moved from the volatile memory 108 to the non-volatile memory 110.

[0041] In contrast, in this embodiment, the data recording device 4 includes a nonvolatile memory 14, a high-performance nonvolatile memory 12 that has a faster processing speed than the nonvolatile memory 14, and an access control unit 10 that controls writing of data to each of the nonvolatile memory 14 and the high-performance nonvolatile memory 12 based on an index related to the temperature of the nonvolatile memory 14. The access control unit 10 (a) writes data to the nonvolatile memory 14 when the index satisfies a first condition, and (b) writes data to the high-performance nonvolatile memory 12 and moves the data from the high-performance nonvolatile memory 12 to the nonvolatile memory 14 when the index satisfies a second condition.

[0042] According to this, the access control unit 10 selects either the high-performance nonvolatile memory 12 or the nonvolatile memory 14 as the data write destination based on an index related to the temperature of the nonvolatile memory 14. As a result, the data is written to either the high-performance nonvolatile memory 12 or the nonvolatile memory 14, so that data loss can be prevented even if the power supply to the data recording device 4 is suddenly cut off due to a power outage or the like.

[0043] In this embodiment, the data recording device 4 further includes a temperature sensor 16 that detects the temperature of the nonvolatile memory 14 as an index. The first condition is that the temperature detected by the temperature sensor 16 is equal to or lower than a first temperature. The second condition is that the temperature detected by the temperature sensor 16 is higher than a second temperature that is equal to or higher than the first temperature.

[0044] When the temperature of the nonvolatile memory 14 exceeds the second temperature, data is written to the nonvolatile memory 14 via the high-performance nonvolatile memory 12. In this case, data is written to both the high-performance nonvolatile memory 12 and the nonvolatile memory 14, resulting in increased overall power consumption (overall heat generation) of the high-performance nonvolatile memory 12 and the nonvolatile memory 14. However, in this case, data is written to the nonvolatile memory 14 in blocks, which can suppress the occurrence of garbage collection and reduce heat generation from the nonvolatile memory 14 alone. On the other hand, when the temperature of the nonvolatile memory 14 is equal to or lower than the first temperature, data is written directly to the nonvolatile memory 14. In this case, data is not written to the nonvolatile memory 14 in blocks, which reduces power consumption of the high-performance nonvolatile memory 12. However, because data is not necessarily written to the nonvolatile memory 14 in blocks, garbage collection is more likely to occur than in the above case, and heat generation from the nonvolatile memory 14 increases. Therefore, by switching the data write destination between the high-performance nonvolatile memory 12 and the nonvolatile memory 14 depending on the temperature of the nonvolatile memory 14, it is possible to reduce the overall power consumption of the high-performance nonvolatile memory 12 and the nonvolatile memory 14 when data is written directly to the volatile memory 14, and it is possible to suppress heat generation in the volatile memory 14 when data is written to the nonvolatile memory 14 via the high-performance nonvolatile memory 12. The first temperature and the second temperature may be the same temperature or may be different temperatures.

[0045] In addition, in this embodiment, when writing data to the high-performance non-volatile memory 12, (c) if the temperature detected by the temperature sensor 16 is lower than a first temperature, the access control unit 10 sets the transfer size per data transfer from the high-performance non-volatile memory 12 to the non-volatile memory 14 to a first size, and (d) if the temperature detected by the temperature sensor 16 is higher than a second temperature, the access control unit 10 sets the transfer size per data transfer from the high-performance non-volatile memory 12 to the non-volatile memory 14 to a second size smaller than the first size.

[0046] According to this, if the temperature of nonvolatile memory 14 has dropped sufficiently after data has been written to high-performance nonvolatile memory 12, data can be moved from high-performance nonvolatile memory 12 to nonvolatile memory 14 at the first size, thereby enabling data movement in a short time while maintaining the data recording speed in nonvolatile memory 14. On the other hand, if the temperature of nonvolatile memory 14 has not dropped sufficiently after data has been written to high-performance nonvolatile memory 12, data can be moved from high-performance nonvolatile memory 12 to nonvolatile memory 14 at the second size (<first size), thereby suppressing a temperature rise in nonvolatile memory 14 that accompanies the data movement.

[0047] Furthermore, in this embodiment, the control method for the data recording device 4 is a control method for the data recording device 4 that includes a nonvolatile memory 14 and a high-performance nonvolatile memory 12 that has a processing speed faster than that of the nonvolatile memory 14. The control method for the data recording device 4 includes the steps of: writing data to the nonvolatile memory 14 when an index related to the temperature of the nonvolatile memory 14 satisfies a first condition; and writing data to the high-performance nonvolatile memory 12 and transferring the data from the high-performance nonvolatile memory 12 to the nonvolatile memory 14 when the index satisfies a second condition.

[0048] As a result, similar to the above, even if the power supply to the data recording device 4 is suddenly cut off due to a power outage or the like, data loss can be prevented.

[0049] [1-4. Modifications] The data transfer process performed by the data recording device 4 according to the modified example of embodiment 1 will be described with reference to Fig. 4. Fig. 4 is a flowchart showing the flow of the data transfer process performed by the data recording device 4 according to the modified example of embodiment 1. In the flowchart of Fig. 4, the same processes as those in the flowchart of Fig. 2B described above are assigned the same step numbers, and their description will be omitted.

[0050] As shown in FIG. 4, the access control unit 10 determines whether the temperature of the nonvolatile memory 14 is higher than a predetermined temperature (for example, 70° C.) based on the temperature detected by the temperature sensor 16 (S201).

[0051] If the temperature of the nonvolatile memory 14 is higher than a predetermined temperature because the temperature has not dropped sufficiently (YES in S201), the access control unit 10 sets the time interval (hereinafter referred to as the "wait time") for moving data from the high-performance nonvolatile memory 12 to the nonvolatile memory 14 to "long" (an example of the second time) (S301).

[0052] The access control unit 10 transfers data from the advanced nonvolatile memory 12 to the nonvolatile memory 14 using the set wait time "long" (S203). That is, after transferring data from the advanced nonvolatile memory 12 to the nonvolatile memory 14, the access control unit 10 waits a relatively long time before transferring other data from the advanced nonvolatile memory 12 to the nonvolatile memory 14, and repeats this process. Note that the size of data transferred per transfer from the advanced nonvolatile memory 12 to the nonvolatile memory 14 is constant. In this way, when the temperature of the nonvolatile memory 14 is higher than a predetermined temperature, setting the wait time to "long" can suppress the temperature rise of the nonvolatile memory 14 that accompanies the data transfer.

[0053] On the other hand, in step S201, if the temperature of the nonvolatile memory 14 has dropped sufficiently and is equal to or lower than the predetermined temperature (NO in S201), the access control unit 10 sets the wait time to "short" (an example of a first time) (S302). This "short" wait time is shorter than the "long" wait time set in step S201.

[0054] The access control unit 10 moves data from the advanced nonvolatile memory 12 to the nonvolatile memory 14 using the set wait time "short" (S203). That is, after moving data from the advanced nonvolatile memory 12 to the nonvolatile memory 14, the access control unit 10 waits a relatively short time before moving other data from the advanced nonvolatile memory 12 to the nonvolatile memory 14, and repeats this process. Note that the size of data moved per transfer from the advanced nonvolatile memory 12 to the nonvolatile memory 14 is constant. In this way, when the temperature of the nonvolatile memory 14 is below a predetermined temperature, by setting the wait time "short," data can be transferred in a short time while maintaining the data recording speed in the nonvolatile memory 14.

[0055] As described above, in this modified example, when data is written to the high-performance non-volatile memory 12, (e) if the temperature detected by the temperature sensor 16 is equal to or lower than the first temperature, the access control unit 10 sets the time interval for transferring data from the high-performance non-volatile memory 12 to the non-volatile memory 14 to a first time, and (f) if the temperature detected by the temperature sensor 16 is higher than the second temperature, the access control unit 10 sets the time interval for transferring data from the high-performance non-volatile memory 12 to the non-volatile memory 14 to a second time longer than the first time.

[0056] According to this, if the temperature of the nonvolatile memory 14 has dropped sufficiently after writing data to the high-performance nonvolatile memory 12, the wait time is set to the first time, thereby making it possible to move the data in a short time while maintaining the data recording speed in the nonvolatile memory 14. On the other hand, if the temperature of the nonvolatile memory 14 has not dropped sufficiently after writing data to the high-performance nonvolatile memory 12, the wait time is set to the second time (>first time), thereby making it possible to suppress the temperature rise of the nonvolatile memory 14 that accompanies the data movement.

[0057] (Embodiment 2) [2-1. Data recording system configuration] The configuration of a data recording system 2A according to embodiment 2 will be described with reference to Fig. 5. Fig. 5 is a block diagram showing the configuration of a data recording system 2A according to embodiment 2. Note that in this embodiment, the same components as those in embodiment 1 above are denoted by the same reference numerals, and their description will be omitted.

[0058] 5, in a data recording system 2A according to the second embodiment, the processing of an access control unit 10A of a data recording device 4A differs from that of the first embodiment. Specifically, when receiving data from a host device 6, the access control unit 10A acquires (calculates) a WAF (Write Amplification Factor) (an example of an index related to the temperature of the nonvolatile memory 14), and selects either the high-performance nonvolatile memory 12 or the nonvolatile memory 14 as a write destination for the data from the host device 6 based on the acquired WAF.

[0059] The WAF refers to the ratio of the data size actually written to the nonvolatile memory 14 to the data size instructed to be written by the host device 6, and is expressed as WAF = (data size actually written to the nonvolatile memory 14) / (data size instructed to be written by the host device 6). If garbage collection occurs as data is written to the nonvolatile memory 14, the amount of data written to the nonvolatile memory 14 increases, and the WAF becomes greater than "1". Normally, the WAF is a value greater than "1", and the smaller the WAF (closer to "1"), the better the WAF condition.

[0060] Note that when data is written directly to the volatile memory 14, the WAF state deteriorates. On the other hand, when data is written to the nonvolatile memory 14 via the high-performance nonvolatile memory 12, the data is written to the nonvolatile memory 14 in blocks, improving the WAF state. In this embodiment, the write destination of data from the host device 6 is switched between the high-performance nonvolatile memory 12 and the nonvolatile memory 14 based on the WAF, which ultimately controls the temperature of the nonvolatile memory 14. Therefore, the WAF can be used as an index related to the temperature of the nonvolatile memory 14.

[0061] [2-2. Operation of the data recording device] Next, the operation of the data recording device 4A according to the second embodiment will be described with reference to Fig. 6. Fig. 6 is a flowchart showing the flow of the operation of the data recording device 4A according to the second embodiment.

[0062] The following describes a case where the host device 6 accesses the data recording device 4A via the network 8 and issues an instruction to write data to the data recording device 4A.

[0063] 6, the access control unit 10A acquires the WAF when receiving data from the host device 6 (S401). The access control unit 10A compares the acquired WAF with a predetermined value (e.g., "1.2") to determine the state of the WAF (S402). At this time, if the WAF is equal to or less than the predetermined value (e.g., WAF≦1.2), the access control unit 10A determines that the WAF state is good. On the other hand, if the WAF is greater than the predetermined value (e.g., WAF>1.2), the access control unit 10A determines that the WAF state is not good.

[0064] If the WAF is in good condition (i.e., if the index satisfies the first condition) (S402: "Good"), the access control unit 10A writes the data from the host device 6 to the nonvolatile memory 14 (S403). At this time, the access control unit 10A writes the data directly to the nonvolatile memory 14 without going through the high-performance nonvolatile memory 12. If the WAF is in good condition, it is considered that the heat generated in the nonvolatile memory 14 is small. Therefore, even if the temperature of the nonvolatile memory 14 rises due to the direct writing of data to the nonvolatile memory 14, there is a margin before the nonvolatile memory 14 reaches a high temperature.

[0065] After step S403, if writing of all the data instructed by the host device 6 is completed (YES in S404), the process ends. On the other hand, if writing of all the data instructed by the host device 6 is not completed (NO in S404), the process returns to step S401 described above.

[0066] On the other hand, if the state of the WAF is not good in step S402 (i.e., if the indicator satisfies the second condition) ("Not Good" in S402), the access control unit 10A writes data from the host device 6 to the advanced nonvolatile memory 12 (S405). If the state of the WAF is not good, it is likely that the power consumption of the nonvolatile memory 14 is relatively high and that the heat generated by the nonvolatile memory 14 is large. Therefore, by writing data to the advanced nonvolatile memory 12, it is possible to suppress the temperature rise of the nonvolatile memory 14.

[0067] After step S405, if writing of all the data instructed by the host device 6 is completed (YES in S404), the process ends. On the other hand, if writing of all the data instructed by the host device 6 is not completed (NO in S404), the process returns to step S401 described above.

[0068] In this embodiment, the data transfer process is performed by the data recording device 4A, as in the first embodiment. The data transfer process in this embodiment is similar to the data transfer process shown in the flowcharts of FIGS. 2B and 4, except that the temperature determination process of the nonvolatile memory 14 in step S201 of FIGS. 2B and 4 is replaced with a process for determining whether the WAF is good or bad (i.e., "when the temperature of the nonvolatile memory 14 is equal to or lower than a predetermined temperature" is replaced with "when the WAF is in a good state," and "when the temperature of the nonvolatile memory 14 is higher than the predetermined temperature" is replaced with "when the WAF is not in a good state"). Specifically, for example, the data transfer size per transfer or the time interval for transferring data is set based on the WAF value, and data is transferred at the set transfer size or time interval. This process is repeated until all of the data written in the high-performance nonvolatile memory 12 has been transferred to the nonvolatile memory 14.

[0069] [2-3. Effects] In this embodiment, the access control unit 10A obtains, as an index, the ratio of the data size actually written to the nonvolatile memory 14 to the data size instructed to be written by the host device 6. The first condition is that the ratio is equal to or smaller than a predetermined value. The second condition is that the ratio is greater than a predetermined value.

[0070] According to this, when the WAF state is good (the ratio is equal to or less than a predetermined value), it is considered that the heat generation in the nonvolatile memory 14 is small, and therefore, even if the temperature of the nonvolatile memory 14 rises due to directly writing data to the nonvolatile memory 14, there is a margin before the nonvolatile memory 14 reaches a high temperature. On the other hand, when the WAF state is not good (the ratio is greater than a predetermined value), it is considered that the power consumption in the nonvolatile memory 14 is relatively high, and the heat generation in the nonvolatile memory 14 is large. Therefore, by writing data to the high-performance nonvolatile memory 12, it is possible to suppress the temperature rise in the nonvolatile memory 14.

[0071] (Other variations, etc.) As described above, the above-mentioned embodiments have been described as examples of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to these, and can be applied to embodiments in which appropriate modifications, substitutions, additions, omissions, etc. are made. Furthermore, it is also possible to combine the components described in the above-mentioned embodiments to create new embodiments.

[0072] Therefore, other embodiments will be exemplified below.

[0073] In each of the above embodiments, the data recording system 2 (2A) is provided with one host device 6, but this is not limitative and the data recording system 2 (2A) may be provided with two or more host devices 6.

[0074] Furthermore, in each of the above embodiments, the nonvolatile memory 14 is an SSD, but this is not limiting, and the nonvolatile memory 14 may be, for example, a removable storage such as a memory card that can be attached to and detached from an adapter.

[0075] In each of the above embodiments, each component may be configured with dedicated hardware, or may be realized by executing a software program suitable for each component. Each component may also be realized by a program execution unit such as a CPU or processor reading and executing a software program recorded on a recording medium such as a hard disk or semiconductor memory.

[0076] Furthermore, some or all of the functions of the data recording device 4 (4A) according to each of the above embodiments may be realized by a processor such as a CPU executing a program.

[0077] As described above, the embodiments have been described as examples of the technology in the present disclosure, and for that purpose, the accompanying drawings and detailed description have been provided.

[0078] Therefore, the components shown in the accompanying drawings and detailed description may include not only essential components for solving the problem, but also components that are not essential for solving the problem in order to illustrate the above technology. Therefore, the fact that these non-essential components are shown in the accompanying drawings or detailed description should not be interpreted as immediately indicating that these non-essential components are essential.

[0079] Furthermore, since the above-described embodiments are intended to illustrate the technology of the present disclosure, various modifications, substitutions, additions, omissions, etc. may be made within the scope of the claims or their equivalents. [Industrial Applicability]

[0080] The present disclosure is applicable to, for example, a data recording device equipped with two nonvolatile memories. [Explanation of symbols]

[0081] 2,2A,100 Data Recording System 4,4A,102 Data recording device 6,104 host devices 8,106 networks 10,10A Access control section 12 High-performance non-volatile memory 14,110 non-volatile memory 16 Temperature Sensor 108 Volatile Memory

Claims

1. a first non-volatile memory; a second nonvolatile memory having a processing speed faster than that of the first nonvolatile memory; an access control unit that acquires, as an index related to the temperature of the first nonvolatile memory, a ratio of a data size actually written to the first nonvolatile memory to a data size instructed to be written by a host device, and controls writing of data to each of the first nonvolatile memory and the second nonvolatile memory based on the index; the access control unit (a) writes data to the first nonvolatile memory when the index satisfies a first condition, and (b) writes data to the second nonvolatile memory and moves data from the second nonvolatile memory to the first nonvolatile memory when the index satisfies a second condition; the first condition is that the ratio is equal to or less than a predetermined value, The second condition is that the ratio is greater than the predetermined value. Data recording device.

2. A method for controlling a data recording device including a first nonvolatile memory and a second nonvolatile memory having a processing speed faster than that of the first nonvolatile memory, comprising: acquiring, as an index related to the temperature of the first nonvolatile memory, a ratio of a data size actually written to the first nonvolatile memory to a data size instructed to be written by a host device; writing data to the first non-volatile memory if the indicator satisfies a first condition; writing data to the second non-volatile memory and migrating data from the second non-volatile memory to the first non-volatile memory when the index satisfies a second condition; the first condition is that the ratio is equal to or less than a predetermined value, The second condition is that the ratio is greater than the predetermined value. A method for controlling a data recording device.

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