JP2005293085A - Data storage device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a data storage device capable of effectively saving data. <P>SOLUTION: The data storage device includes an input means to which data are inputted; a management data creation means for creating management data related to the data; a first storage means for storing the data and the management data; a second storage means for storing the data and the management data stored in the first storage means; a control means for controlling the writing and reading of the first and the second storage means; and a power supply means for supplying power to each of the means. When the data and the management data stored in the first storage means are transferred to the second storage means, the control means controls transfer so that the data are transferred sequentially from the first storage means to the second storage means, and so that the management data are transferred at a time for a plurality of the data. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a data storage device that stores data, for example, and more particularly to a data storage device that uses, for example, a nonvolatile memory.

  FIG. 4 shows an example of a conventional data storage device in which an external memory with a limited number of writes is used, and there is no secondary power supply unit and a power supply monitoring unit. An example of the case where there is a power supply unit and a power supply monitoring unit will be described with reference to FIG. Here, there is no intention to limit the data storage device according to the embodiment of the present invention.

  FIG. 4 is a block diagram showing an example of the configuration of a conventional data storage device. In FIG. 4, reference numeral 400 denotes a power supply unit that supplies power to each unit or unit, and 401 denotes external data such as image data and audio data from a camera or microphone connected to the data storage device (hereinafter, external data 405). This is an external data input interface (I / F) that accepts an input of “. Reference numeral 402 denotes a control unit such as a CPU (Central Processing Unit) that performs predetermined arithmetic processing such as control of the entire data storage device and data processing, and operates according to a built-in control program. Reference numeral 403 denotes an internal memory composed of a volatile semiconductor memory such as SRAM or DRAM, and reference numeral 404 denotes an external memory composed of a nonvolatile semiconductor memory such as a memory card such as a compact flash (registered trademark). When a memory card is used as the external memory 404, the external memory 404 is coupled to an input / output interface (not shown) and is configured to be detachable from the data storage device body. In this specification, 404 is referred to as an external memory. However, as long as it is a non-volatile storage device, there is no distinction between internal and external. The external data input interface 401, the internal memory 403, and the external memory 404 are controlled by the control unit 402 connected via the data bus 408. The power supply unit 400 is connected to the control unit 402, the internal memory 403, and the external memory 404, and is supplied with power.

  In FIG. 4, external data 405 input from the external data input interface 401 is input to the control unit 402 via the data bus 408. The control unit 402 generates a set of management data 406 and acquisition data 407 based on the input external acquisition data 405. For example, when the external data 405 is video data, the management data 406-1 and 406-2 are based on the external data 405-1, 405-2,. ,... 406-n and acquired data 407-1, 4-7-2,. Here, for example, the management data 406-1 and the acquisition data 407-1 for the external data 405-1 are set as one set. Management data 406 and acquired data 407 generated by the control unit 402 are input to the internal memory 403 and stored in the internal memory 403.

  Here, the acquired data 407 is data obtained by executing data processing. For example, the acquired data 407 is data obtained by performing predetermined compression encoding processing on the external data 405, but other processing is performed. Data obtained by execution may be used, and various modes such as the external data 405 itself as the acquired data 407 may be used. For example, when the external data 405 is image data, the acquired data 407 is JPEG image data obtained by compression-coding the external data 405. On the other hand, the management data 406 is data in which management information such as the generation date and time of the acquisition data 407, the creator, the relationship with the other acquisition data 407, the data size, and the like are recorded. In the case of image data obtained by (not shown), the management data 406 is the shooting date / time, shooting location, image data size, etc. of each image data. Here, in addition to the management data 406 generated by the control unit 402, for example, data generated in the camera or the like and input to the control unit 402 of the data storage device may be used.

  Further, the management data 406 and the acquired data 407 stored in the internal memory 403 under the control of the control unit 402 are sequentially transferred to the external memory 404 in pairs, and stored in the external memory 404.

  FIG. 5 is a block diagram showing another example of the configuration of the conventional data storage device, and the same components as those in FIG. 4 are denoted by the same reference numerals. 5, in addition to the configuration of FIG. 4, a power supply monitoring unit 500, a current backflow prevention unit 501, and a secondary power supply unit 502 are newly added. The following description focuses on the newly added configuration.

  In FIG. 5, external data 405 input from the external data input interface 401 is input to the control unit 402 via the data bus 408. The control unit 402 generates a set of management data 406 and acquired data 407 based on the input external data 405. Under the control of the control unit 402, the management data 406 and the acquired data 407 are input to the internal memory 403 and stored in the internal memory. Further, the management data 406 and the acquired data 407 stored in the internal memory 403 under the control of the control unit 402 are sequentially transferred to the external memory 404 in pairs, and stored in the external memory 404.

  Here, the power supply unit 400 is connected to the power supply monitoring unit 500 and the current backflow prevention unit 501. The power output from the current backflow prevention unit 501 is supplied to the control unit 402, the internal memory 403, the external memory 404, and the like via the secondary power supply unit 502. Here, when the voltage of the power supply unit 400 is normal, for example, the secondary power supply unit 502 is in a state where power is charged from the power supply unit 400, but the voltage of the power supply unit 400 fluctuates or is disconnected. In this case, the secondary power supply unit 502 is automatically activated according to fluctuations and the like, and supplies the charged power to the control unit 402, the internal memory 403, the external memory 404, and the like. When the power supply unit 400 is changed or disconnected, the power supply monitoring unit 500 detects a change in the input voltage from the power supply unit 400 and notifies the control unit 402 of the detection information. The control unit 402 that has received the detection information from the power supply monitoring unit 500 transfers the untransferred management data 406 and the acquired data 407 in the internal memory 403 to the external memory 404. The current backflow prevention unit 501 plays a role of preventing backflow of current supplied from the secondary power supply unit 502.

Conventionally, an application example of a system that backs up data with a backup power source when the power is turned off has been studied (for example, see Patent Document 1).
JP 2003-6056 A

  However, for example, in the conventional apparatus as shown in FIG. 4, when the voltage of the power supply unit 400 fluctuates or is disconnected, the untransferred management data 406 and the acquired data 407 in the internal memory 403 are discarded. For example, there is a problem that the external data 405 is not sufficiently stored.

  Further, for example, in the conventional apparatus as shown in FIG. 5, the secondary power supply unit 502 is activated when the power supply unit 400 changes, so that while the power is supplied from the secondary power supply unit 502, Since the untransferred management data 406 and acquired data 407 in the internal memory 403 can be transferred to the external memory 404, the problem of saving the external data 405 is improved. However, in the conventional apparatus as shown in FIG. 5, the management data 406 and the acquisition data 407 in the internal memory 403 are paired even during a normal operation in which the voltage of the power supply unit 400 does not fluctuate or disconnect. In order to transfer the data to the external memory 404 one by one, frequent rewriting occurs in the storage area in the external memory 404 allocated for the management data 406 whose amount of data is sufficiently small compared to the acquired data. There has been a problem that the number of rewritable times of the external memory 404 is reached in a short time, and the life of the external memory 404 is shortened.

  The present invention has been made in view of such a conventional situation, and an object of the present invention is to provide a data storage device capable of reducing the number of times data is rewritten in a memory where the number of times of writing is limited. To do.

  Another object of the present invention is to provide a data storage device that can effectively store data, for example.

  In order to achieve the above object, in the data storage device according to the present example, input means for inputting data, management data generation means for generating management data related to the data, the data and the management data are stored. First storage means, second storage means for storing data and management data stored in the first storage means, control means for controlling writing and reading of the first and second storage means, and The following processing is performed in a configuration including power supply means for supplying power to each means. That is, in the control means, when the data stored in the first storage means and the management data are transferred to the second storage means, the data is sequentially transferred from the first storage means to the second storage. The management data is controlled so as to transfer a plurality of the data collectively.

  Here, various data may be used, and for example, digital image data, analog video signals, audio data, and the like can be used. Here, as the image data, moving image data may be used, or still image data may be used. Various kinds of management data may be used. For example, information related to data such as data generation date / time, generation location and generation person, information for referring to a location where the data is stored, and the like are used. be able to.

  In the data storage device according to the present invention, as one configuration example, the first storage means is configured by a volatile memory provided in the data storage device, and the second storage means is the data storage. It is composed of a non-volatile memory provided outside the apparatus.

  Here, various types of volatile memory may be used. The second storage means is configured as an internal device constituting the data storage device, or as an external device from the data storage device. Various types of nonvolatile memory may be used. For example, a flash memory or the like can be used. Various external nonvolatile memories may be used. For example, a memory card such as a compact flash (registered trademark) may be used.

  The data storage device according to the present invention further includes power supply monitoring means as one configuration example. The power supply monitoring means supplies change information to the control means when detecting a change in the power supply means. Further, the control means transfers the management data remaining in the first storage means to the second storage means based on the change information. Here, various changes in the power supply means may be used. For example, a change in voltage, power or the like exceeding a predetermined value of the power supply means may be used.

  Below, the structural example which concerns on this invention is shown further. The data storage device according to the present invention further includes secondary power supply means as one configuration example. That is, when the power supply monitoring means detects a change in the power supply means, the power supply monitoring means supplies change information of the power supply means to the control means, and the control means supplies the secondary power supply means. Start. Alternatively, the secondary power supply is activated in response to a change in the power supply means.

  In the image transmission apparatus according to the present invention, input means for inputting data, management data generation means for generating management data related to the data, and first storage means for storing the data and the management data And a second storage means for storing data and management data stored in the first storage means, and a control means for controlling writing and reading of the first and second storage means, The following processing is performed. That is, when transferring the data and management data stored in the first storage means to the second storage means, the control means makes the data transfer cycle different from the management data transfer cycle. To control.

  As described above, in the data storage device according to the present invention, for example, the number of data rewrites in a memory with a limited number of writes can be reduced, and for example, data can be effectively stored.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing an example of the configuration of a data storage device according to the present invention. The same components as those in FIGS. 4 and 5 are denoted by the same reference numerals and detailed description thereof will be omitted. However, since the operation of the control unit 101 is different, the following description will focus on the operation of the control unit 101 in detail. explain.

  First, the operation until the external data 405 input from the external data input interface 401 is stored in the internal memory 403 as management data 406 and acquired data 407 will be described with reference to FIG.

  In FIG. 2, first, external data 405 is input (acquired), for example, by one data from the external data input interface 401 to the control unit 101 (step 201). Here, one data corresponds to, for example, one frame of video data. Next, based on the external data 405 input in step 201, the control unit 101 generates a set of acquisition data 407 and management data 406 (step 202). Next, the acquired data 407 is stored in the internal memory 403 (step 203), the management data 406 corresponding to the acquired data 407 stored in step 203 is stored in the internal memory 403 (step 204), and the first step 201 is performed. Return.

  As described above, the control unit 101 takes in the external data 405 from the external data input interface 401 one by one, for example, and stores the corresponding management data 406 and acquired data 407 in pairs in the internal memory 403 one after another. Go.

  Here, the management data 406 and the acquired data 407 stored in the internal memory 403 are, for example, a nonvolatile semiconductor memory when a user instruction or an abnormality detection signal is input from an external sensor (not shown). Are transferred to the external memory 404.

  Next, an operation when the management data 406 and the acquisition data 407 stored in the internal memory 403 are transferred to the external memory 404 will be described with reference to FIG. In FIG. 3, the transfer periods of the management data 406 and the acquired data 407 from the internal memory 403 to the external memory 404 are made different from each other.

  In FIG. 3, when the transfer operation to the external memory 404 is started, it is first determined whether or not the current transfer count value is equal to or greater than a predetermined value N (step 301). If the current transfer count is less than the predetermined value N, the process branches to step 302. Here, the predetermined value N is a preset value and can be arbitrarily set according to the actual system setting status.

  In step 302, of the data stored in the internal memory 403, for example, only one piece of acquired data 407 is transferred to the external memory 404 and stored in the external memory 404. Next, for example, the value of the counter for counting the number of transfers of the control unit 101 is incremented by 1, and the process returns to the first step 301 (step 303).

If it is determined in step 301 that the current transfer count is equal to or greater than the predetermined value N, the process branches to step 304.
In step 304, the acquired data 407 stored in the internal memory 403 is transferred to the external memory 404, for example, for one data, and management data 406 for N data corresponding to the acquired data 407 that has already been transferred. The data is collectively transferred to the external memory 404, and the acquisition data 407 for one data and the management data 406 for N data are stored in the external memory 404. Next, the current transfer count is reset to the initial value 1, and the process returns to the first step 301 (step 305).

  Here, the operation of the above-described control unit 101 will be described in time series with reference to FIG. In FIG. 6, two operations of storing data from the external data input interface 401 to the internal memory 403 and transferring data from the internal memory 403 to the external memory 404 are described as a series of operations. In an actual system, a difference in writing speed between the internal memory 403 and the external memory 404, other control (not shown) performed by the control unit 101, for example, a process of transmitting stored data to others via a network, In consideration of the processing load of the control unit 101 due to the process of compressing and encoding data, the process of decoding data, and the like, as shown in FIGS. It is executed by.

  In FIG. 6, the horizontal axis represents time, and the vertical axis represents the operation content of the control unit 101 at each time. FIG. 6 illustrates the case where the predetermined value N is 5 as an example. The control unit 101 is divided into a case where the number of transfers is 1 to 4 and a case where the number of transfers is 5. Represents the operation content.

  In FIG. 6, when the number of transfers is 1 to 4, the control unit 101 takes in the external data 405 from the external data input interface 401 (step 600), and generates a set of management data 406 and acquired data 407 (step 601). ). Next, the set of management data 406 and acquired data 407 is stored in the internal memory 403 (step 602). Next, only the acquired data 407 in the internal memory 403 is transferred to the external memory 404, and the management data 406 corresponding to the transferred acquired data 407 is not transferred to the external memory 404 (step 603). By repeating this, four data of management data 406-1 to 406-4 remain in the internal memory 403.

  When the transfer count = 5, the control unit 101 takes in the external data 405 from the external data input interface 401 (step 600), and generates a set of management data 406 and acquired data 407 (step 601). Next, the set of management data 406 and acquired data 407 is stored in the internal memory 403 (step 602). Next, since the number of transfers has reached the predetermined value N = 5, one piece of acquired data 407 and management data 406 that has not been transferred so far, that is, here, management data 406-1- Five pieces of management data 406 406-5 are collectively transferred to the external memory 404.

  As described above, in the data storage device according to the present invention, the management data 406 and the acquired data 407 from the internal memory 403 to the external memory 404 during normal operation in which the voltage of the power supply unit 400 does not fluctuate or disconnect. The acquired data 407 is sequentially transferred while the management data 406 is transferred in batches.

  Next, an operation when the voltage of the power supply unit 400 fluctuates or is disconnected will be described with reference to FIG. In FIG. 7, first, when a change or disconnection occurs in the power supply unit 400, the power supply monitoring unit 500 detects a change in the input voltage that is equal to or greater than a predetermined value from the power supply unit 400, (Step 701). Here, the fluctuation or disconnection of the voltage occurs due to, for example, a failure of the power supply unit 400 or a power failure due to a power failure or the like. At this time, the secondary power supply unit 502 is automatically activated in accordance with the fluctuation or disconnection of the voltage of the power supply unit 400 (step 702). As another example, the secondary power supply unit 502 may be configured to be activated in response to a command from the control unit 101 that has received detection information from the power supply monitoring unit 500.

  Next, the control unit 101 that has received the detection information from the power supply monitoring unit 500 suppresses the operation of a function unit (not shown) other than the internal memory 403 and the external memory 404, for example, stops execution of a control program for the function unit. To put the system into a low power consumption state (step 703).

  Next, the control unit 101 checks whether there is any untransferred management data 406 corresponding to the acquired data 407 already transferred to the external memory 404 in the internal memory 403 (step 704). ). If there is untransferred management data 406 corresponding to the acquired data 407 that has been transferred, the control unit 101 first executes the operation of transferring the management data 406 to the external memory 404 with the highest priority (step 705). . When there is no untransferred management data 406 corresponding to the acquired data 407 that has been transferred, or when the transfer of the untransferred management data 406 in step 705 is completed, the control unit 101 receives the data from the secondary power supply unit. While the power is held above the predetermined value, for example, the remaining untransferred acquisition data 407 in the internal memory 403 is transferred to the external memory 404 (step 706).

  As described above, during a normal operation in which the power supply unit 400 does not fluctuate or disconnect, the control unit 101 sets the transfer cycle of the management data 406 to be longer than the transfer cycle of the acquired data 407, and manages a plurality of pieces of management. The data 406 is collectively transferred to the external memory 404. When the power supply unit 400 fluctuates or disconnects, the control unit 101 does not yet transfer the management data 406 corresponding to the acquired data 407 that has already been transferred to the external memory 404 to the external memory 404. The operation of transferring the data to the external memory 404 is executed with the highest priority, the number of data rewrites to the external memory 404 is reduced, and, for example, important data can be effectively saved.

  In the above-described embodiment, the predetermined value N is set to 5, and five pieces of management data 406 are collectively transferred to the external memory 404. However, the management data transfer cycle, that is, how much of the management data 406 is transferred. Whether the management data 406 is collectively transferred to the external memory 404 may be set to various values according to the actual system setting status. As an example, considering the time during which power supply from the secondary power supply unit 502 continues when the power supply unit 101 fluctuates or is disconnected, and the data writing speed to the external memory 404, the external power supply from the secondary power supply unit 502 A predetermined value N is set so as not to exceed the amount of data that can be transferred to the memory 404.

  In the above-described example, the management data 406 is management information such as the generation date and time of the acquired data 407 and the data size. However, the management data is not limited to these, and is stored in, for example, a memory. It may be a file that becomes a list of the acquired data 407 or a file for referring to a storage location of the acquired data 407 (for example, a file that has an effect of shortening the time when the acquired data 407 is read from the memory). . For example, when the management data 406 is a file for referring to the storage location of the acquired data 407, the control unit 101 stores the acquired data 407 generated from the external data 405 in the internal memory 403. Is stored, and the acquired address information is stored in the internal memory 403 as management data 406. Further, when transferring the acquired data 407 to the external memory 404, the control unit 101 acquires the address of the storage area on the external memory 404 that stores the acquired data 407, and stores the acquired address information in the internal memory 403. (For example, when the number of transfers is 1 to 4 in FIG. 6). Then, five pieces of address information (addresses on the external memory 404) in the internal memory 403 temporarily held are collectively transferred to the external memory 404 and stored in the external memory 404 as management data 406 ′ (see FIG. For example, the number of transfers in FIG. 6 = 5).

  Next, the case where the above-described data storage device according to the present invention is realized as an encoder (image transmission device) used in a network distribution type monitoring system will be described. FIG. 8 is a diagram illustrating a configuration example of a network distribution type monitoring system. In FIG. 8, 801 is a surveillance camera, 802 is an infrared sensor installed corresponding to the imaging range of the surveillance camera 801, an external sensor such as a vibration sensor, 803 is an encoder, 804 is a network such as the Internet, 805 is a personal computer (Personal) A client terminal such as a computer (PC).

  In FIG. 8, when an image distribution request is made from the client terminal 805 to the encoder 803, the encoder 803 compresses and encodes the video signal acquired from the monitoring camera 801 and outputs it to the network 804 as, for example, JPEG format image data. And distributed to the client terminal 805. Here, the configuration of the encoder 803 includes, for example, the configuration shown in FIG. That is, the external data input interface 401 in FIG. 1 is an input interface to which a video signal from the monitoring camera 801 is input in FIG. 8 and is provided at the input end of the encoder 803.

  Therefore, the control unit 101 of the encoder 803 generates JPEG format image data from the video signal that is the external data 405, stores the image data in the internal memory 403 as the acquisition data 407, and management data for the acquisition data 407. 406 is stored in the internal memory 403. Here, as the management data 406, for example, data generated by the monitoring camera 801 or the encoder 803 itself is used.

  For example, the encoder 803 reserves an area in the internal memory 403 where image data generated from a video signal input from the monitoring camera 801 can be stored for a predetermined frame, and a new image input from the monitoring camera 801. Data is stored in the internal memory 403 frame by frame, and when the storage capacity is full, old image data is sequentially overwritten and recorded. As described above, when an image distribution request is received from the client terminal 805, the image data (acquired data 407) stored in the internal memory 403 is sequentially read out and distributed to the client terminal 805 via the network 804. .

  Here, when the external sensor 802 reacts and an alarm signal is input from the external sensor 802 to the encoder 803, the encoder 803 until the alarm ends from image data a predetermined time before the alarm signal is input. The image data is recorded in the external memory 404 (pre-alarm recording). At this time, as described above, the control unit 101 of the encoder 803 changes the transfer period of the image data (acquired data 407) in the internal memory 403 and the management data 406, and the management data 406 has a predetermined number of frames. The management data 406 corresponding to the image data (acquired data 407) is transferred to the external memory 404 and written to the external memory 404. In addition, when data stored in the internal memory 403 is transferred to the external memory 404 by pre-alarm recording, if there is a change in the power supply unit 400, the image data (acquired) transferred to the external memory 404 is acquired. The transfer operation of the management data 406 corresponding to the data 407) is executed with the highest priority. Therefore, in the encoder 803, the number of times of writing to the external memory 404 is reduced, and the external memory 404 can effectively save the image data of the important scene generated at the time of the alarm. In addition to the method of detecting the alarm by the external sensor 802 described above, for example, a method of performing image recognition processing on the video of the monitoring camera 801 and detecting an intruding object or the like in the video may be used.

  In the data storage device of this example, the input unit is configured by the function of the external data input interface 401, the management data generation unit and the control unit are configured by the function of the control unit 101, and the function of the power supply unit 400 is configured. The power supply unit is configured by the internal memory 403, and the first storage unit is configured by the function of the internal memory 403, and the second storage unit is configured by the function of the external memory 404. Further, in the data storage device of this example, a power supply monitoring unit is configured by the function of the power supply monitoring unit 500, and a secondary power supply unit is configured by the function of the secondary power supply unit 502.

  Here, the configuration of the data storage device according to the present invention is not necessarily limited to that described above, and various configurations may be used. The present invention can also be provided as a method or method for executing the processing according to the present invention, a program for realizing such a method or method, and the like, for example, a data storage device or the like. It can also be provided as various devices and systems.

  The application field of the present invention is not necessarily limited to the above-described fields, and the present invention can be applied to various fields. For example, the present invention is not limited to application to the encoder described above, and can be realized as various devices.

  Further, as various processes performed in the data storage device according to the present invention, for example, the processor executes a control program stored in a ROM (Read Only Memory) in a hardware resource including a processor, a memory, and the like. A controlled configuration may be used, and for example, each functional unit for executing the processing may be configured as an independent hardware circuit.

  Further, the present invention can be grasped as a computer-readable recording medium such as a floppy (registered trademark) disk or a CD (Compact Disc) -ROM storing the control program, or the program (itself). The processing according to the present invention can be performed by inputting the program from the recording medium to the computer and causing the processor to execute the program.

It is a figure which shows the structural example of the data storage device based on one Example of this invention. It is a figure which shows an example of the flow of a process which memorize | stores data in the internal memory which concerns on one Example of this invention. It is a figure which shows an example of the flow of a process which transfers data to the external memory which concerns on one Example of this invention. It is a figure which shows the structural example of a data storage device. It is a figure which shows the structural example of a data storage device. It is a figure which shows an example of the flow of the data processing which concerns on one Example of this invention. It is a figure which shows an example of the process at the time of the power supply fluctuation which concerns on one Example of this invention. It is a figure which shows the structural example of a network monitoring system.

Explanation of symbols

101: control unit, 400: power supply unit, 401: external data input interface, 402: control unit, 403: internal memory, 404: external memory, 405: external data, 406: management data, 407: acquisition data, 408: data Bus, 500: power supply monitoring unit, 501: current backflow prevention unit, 502: secondary power supply unit

Claims (3)

Input means for inputting data, management data generation means for generating management data related to the data, first storage means for storing the data and the management data, and stored in the first storage means Second storage means for storing data and management data, control means for controlling writing and reading of the first and second storage means, and power supply means for supplying power to each means,
When the control means transfers data and management data stored in the first storage means to the second storage means, the data is sequentially transferred from the first storage means to the second storage means. A data storage device, wherein the management data is controlled to be transferred in batches for a plurality of the data. The data storage device of claim 1, wherein
The first storage means is a volatile memory provided inside the data storage device,
The data storage device, wherein the second storage means is a non-volatile memory provided outside the data storage device. The data storage device according to claim 1 and claim 2,
Furthermore, a power supply monitoring means is provided,
When the power monitoring means detects a change in the power supply means, the power monitoring means supplies change information of the power supply means to the control means,
The data storage device, wherein the control means transfers the management data remaining in the first storage means to the second storage means based on the change information.