Patent Publication Number: US-2009222614-A1

Title: Information processing apparatus and nonvolatile semiconductor memory drive

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a Continuation Application of PCT Application No. PCT/JP2008/070720, filed Nov. 7, 2008, which was published under PCT Article 21(2) in English. 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2008-050809, filed Feb. 29, 2008, the entire contents of which are incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     One embodiment of the present invention relates to an information processing apparatus and a nonvolatile semiconductor memory drive. 
     2. Description of the Related Art 
     There are computers which store log data. As an information processing apparatus having such a log data management function, there is known an information processing apparatus which is disclosed, for instance, in Jpn. Pat. Appln. KOKAI Publication No. 2006-113961. 
     This information processing apparatus stores log information, which includes the content of a user operation and information relating to an occurring event, in association with time information. On the basis of the log information, this information processing apparatus estimates a future operation condition. 
     In this information processing apparatus, however, in order to check the information of the operation content and the occurring event on the basis of the log information, it is necessary to select necessary information from the log information and to rearrange the selected information. It is thus difficult to easily understand a cause of, e.g. a fault, or an indication of abnormality which would lead to a failure of devices. In addition, each time an event or the like occurs, the data amount of the log information increases. Consequently, a great amount of memory is necessary for storing log information. It is thus required to realize a novel function for easily rearranging and analyzing information which is to be monitored. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       A general architecture that implements the various feature of the invention will now be described with reference to the drawings. The drawings and the associated descriptions are provided to illustrate embodiments of the invention and not to limit the scope of the invention. 
         FIG. 1  is a perspective view showing the external appearance of an information processing apparatus according to an embodiment of the present invention; 
         FIG. 2  is a block diagram which schematically shows the structure of the information processing apparatus according to the embodiment; 
         FIG. 3  is a block diagram which schematically shows the structure of an SSD that is used in the information processing apparatus according to the embodiment; 
         FIG. 4  schematically shows an example of the memory capacities and memory areas of the SSD shown in  FIG. 3 ; 
         FIG. 5  schematically shows the structure of a NAND memory which is provided in the SSD shown in  FIG. 3 ; 
         FIG. 6  shows an example of statistical information which is stored in the NAND memory provided in the SSD shown in  FIG. 3 ; 
         FIG. 7  schematically shows an example of a storage format of monthly information which is stored in the NAND memory provided in the SSD shown in  FIG. 3 ; 
         FIG. 8  is a flow chart illustrating an example of the procedure of a monthly information storing process which is executed by the SSD shown in  FIG. 3 ; 
         FIG. 9  schematically shows another example of the storage format of monthly information which is stored in the NAND memory provided in the SSD shown in  FIG. 3 ; and 
         FIG. 10  is a flow chart illustrating another example of the procedure of the monthly information storing process which is executed by the SSD shown in  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION 
     Various embodiments according to the invention will be described hereinafter with reference to the accompanying drawings. In general, according to one embodiment of the invention, there is provided An information processing apparatus comprising: an information processing apparatus main body; and a nonvolatile semiconductor memory drive which is accommodated in the information processing apparatus main body, the nonvolatile semiconductor memory drive including a nonvolatile semiconductor memory, and a control module configured to control, in accordance with a command from the information processing apparatus main body, a write operation, a read operation and an erase operation of the nonvolatile semiconductor memory, to generate, in every predetermined time period, statistical information relating to the write operation, the read operation and the erase operation of the nonvolatile semiconductor memory, and to store the statistical information, which corresponds to each of a plurality of time periods each having a time length corresponding to the predetermined time period, in a memory area of the nonvolatile semiconductor memory. 
     According to this information processing apparatus, information which is to be monitored can easily be rearranged and analyzed. 
     &lt;Structure of the Information Processing Apparatus&gt; 
       FIG. 1  is a perspective view showing the external appearance of an information processing apparatus according to an embodiment of the present invention. This information processing apparatus  1 , as shown in  FIG. 1 , is composed of an information processing apparatus main body  2  and a display unit  3  which is attached to the information processing apparatus main body  2 . 
     The main body  2  has a box-shaped casing  4 . The casing  4  includes an upper wall  4   a,  a peripheral wall  4   b  and a lower wall (not shown). The upper wall  4   a  of the casing  4  includes a front part  40 , a central part  41  and a back part  42  in the named order from the side close to a user who operates the information processing apparatus  1 . The lower wall is positioned on the side opposite to the upper wall  4   a  and is opposed to an installation surface on which the information processing apparatus  1  is disposed. The peripheral wall  4   b  includes a front wall  4   ba,  a rear wall  4   bb  and left and right side walls  4   bc  and  4   bd.    
     The front part  40  includes a touch pad  20  which is a pointing device, a palm rest  21 , and an LED  22  which is turned on in association with the operation of respective parts of the information processing apparatus  1 . 
     The central part  41  includes a keyboard mounting part  23  to which a keyboard  23   a,  which can input character information, etc., is attached. 
     The back part  42  includes a battery pack  24  which is detachably attached. A power switch  25  for powering on the information processing apparatus  1  is provided on the right side of the battery pack  24 . A pair of hinge portions  26   a  and  26   b,  which rotatably support the display unit  3 , are provided on the left and right sides of the battery pack  24 . 
     An exhaust port  29  for exhausting the wind W to the outside from the inside of the casing  4  is provided on the left side wall  4   bc  of the casing  4 . In addition, an ODD (Optical Disc Drive)  27 , which can read and write data on an optical storage medium such as a DVD, and a card slot  28 , in/from which various cards can be inserted/taken out, are disposed on the right side wall  4   bd.    
     The casing  4  is formed of a casing cover including a part of the peripheral wall  4   b  and the upper wall  4   a,  and a casing base including a part of the peripheral wall  4   b  and the lower wall. The casing cover is detachably coupled to the casing base, and an accommodation space is formed between the casing cover and the casing base. This accommodation space accommodates, for instance, an SSD (Solid State Drive)  10  functioning as a nonvolatile semiconductor memory drive. The details of the S  10  will be described later. 
     The display unit  3  includes a display housing  30  having an opening portion  30   a,  and a display device  31  which is composed of, e.g. an LCD which can display an image on a display screen  31   a.  The display device  31  is accommodated in the display housing  30 , and the display screen  31   a  is exposed to the outside of the display housing  30  through the opening portion  30   a.    
     The casing  4  accommodates a main circuit board, an expansion module, a fan, etc., which are not shown, in addition to the above-described SSD  10 , battery pack  24 , ODD  27  and card slot  28 . 
       FIG. 2  is a block diagram which schematically shows the system configuration of the information processing apparatus  1 . 
     The information processing apparatus  1 , as shown in  FIG. 2 , includes an EC (Embedded Controller)  111 , a flash memory  112  which stores a BIOS (Basic Input Output System)  112   a,  a south bridge  113 , a north bridge  114 , a CPU (Central Processing Unit)  115 , a GPU (Graphic Processing Unit)  116  and a main memory  117 , in addition to the above-described SSD  10 , expansion module  12 , fan  13 , touch pad  20 , LED  22 , keyboard  23   a,  power switch  25 , ODD  27 , card slot  28  and display device  31 . 
     The EC (Embedded Controller)  111  is a built-in system which controls the respective parts. The north bridge  114  is an LSI which controls connection between the CPU  115 , CPU  116 , main memory  117  and various buses. The CPU  15  is a processor which performs arithmetic processing of various signals, and executes an operating system and various application programs, which are loaded from the SSD  10  into the main memory  117 . The GPU  116  is a display controller which executes display control by performing arithmetic processing of a video signal. 
     The expansion module  12  includes an expansion circuit board, a card socket which is provided on the expansion circuit board, and an expansion module board which is inserted in the card socket. The card socket supports, e.g. the Mini-PCI standard. Examples of the expansion module board include a 3G (3rd Generation) module, a TV tuner, a GPS module, and a Wimax (trademark) module. 
     The fan  13  is a cooling unit which cools the inside of the casing  4  on the basis of air feeding, and exhausts the air in the casing  4  to the outside as the wind W via the exhaust port  29 . 
     The EC  111 , flash memory  112 , south bridge  113 , north bridge  114 , CPU  115 , GPU  116  and main memory  117  are electronic components which are mounted on the main circuit board. 
     &lt;Structure of SSD&gt; 
       FIG. 3  is a block diagram which schematically shows the structure of the SS that is applied to the information processing apparatus according to the embodiment. 
     The SSD  10  is a nonvolatile semiconductor memory drive which, in place of a hard disk, is used as an external storage device of the information processing apparatus  1 . The SSD  10 , as shown in  FIG. 3 , substantially comprises a temperature sensor  101 , a connector  102 , a control unit  103 , NAND memories (NAND flash EEPROMs)  104 A to  104 H, a DRAM (memory)  105 , and a power supply circuit  106 . The SSD  10  is the external storage device which stores data and programs, and the storage content of which is not lost even if no power is supplied. The SSD  10  is a drive which, unlike a hard disk drive, does not have a driving mechanism of a magnetic disk, a head, etc., but the SSD  10  can store programs, such as the OS (Operating System), and data which is created by the user or created on the basis of software, in memory areas of a NAND memory, which is a nonvolatile semiconductor memory, for a long time in a readable/writable manner, and can operate as a boot drive of the information processing apparatus  1 . 
     The control unit  103  is connected to the connector  102 , eight NAND memories  104 A to  104 H, DRAM  105  and power supply circuit  106 . In addition, the control unit  103  is connected to the host apparatus  8  via the connector  102 , and is connected, where necessary, to an external apparatus  9 . 
     A power supply  7  is the batter pack  24  or an AC adapter (not shown). For example, a power of DC 3.3V is supplied to the power supply circuit  106  via the connector  102 . In addition, the power supply  7  supplies power to the entirety of the information processing apparatus  1 . 
     In the present embodiment, the host apparatus  8  is the information processing apparatus main body  2  (the main circuit board of the main body  2 ). The south bridge  113 , which is mounted on the main circuit board, is connected to the control unit  103  via the connector  102 . Data transmission/reception is executed between the south bridge  113  and control unit  103 , for example, on the basis of the serial ATA standard. 
     The external apparatus  9  is an information processing apparatus which is different from the information processing apparatus  1 . The external apparatus  9  is connected to the control unit  103  of the SSD  10  which is removed from the information processing apparatus  1 , for example, on the basis of the RS-232C standard, and the external apparatus  9  has a function of reading out data which is stored in the NAND memories  104 A to  104 H. 
     The board, on which the SSD  10  is mounted, has the same outside size as an HDD (Hard Disk Drive) of, e.g. 1.8-inch type or 2.5-inch type. In the present embodiment, this board has the same outside size as the 1.8-inch type HDD. 
     The control unit  103  is a control module configured to control a write operation, a read operation and an erase operation of the NAND memories  104 A to  104 H in accordance with a command from the information processing apparatus main body  2 . Specifically, in accordance with a request (read command, write command, or other various commands) from the information processing apparatus main body  2  that functions as the host apparatus  8 , the control unit  103  controls the execution of data read, write and erase operations on the NAND memories  104 A to  104 H. The data transfer speed is, for example, 100 MB/Sec at a data read and 40 MB/Sec at a data write. 
     Each of the NAND memories  104 A to  104 H is a nonvolatile semiconductor memory having a memory capacity of, e.g. 16 GB. Each of the NAND memories  104 A to  104 H is composed of, e.g. an MLC (Multi-Level Cell)-NAND memory (multilevel NAND memory) in which 2 bits can be recorded in one memory cell. The MLC-NAND memory has such features that the allowable number of rewrites is smaller than an SLC (Single-Level Cell)-NAND memory, but the memory capacity can be increased more easily than the SLC (Single-Level Cell)-NAND memory. 
     The DRAM  105  is a buffer which temporarily stores data when data read/write is executed on the NAND memory,  104 A to  104 H, by the control of the control unit  103 . 
     The connector  102  has a shape based on, e.g. the serial ATA standard. The control unit  103  and power supply circuit  106  may be connected to the host apparatus  8  and power supply  7  via different connectors. 
     The power supply circuit  106  converts DC 3.3V, which is supplied from the power supply  7 , to, e.g. DC 1.8V and 1.2V, and supplies these three kinds of voltages to the respective parts in accordance with the driving voltages of the respective parts of the SSD  10 . 
     &lt;Memory Capacity of SSD&gt; 
       FIG. 4  schematically shows an example of the memory capacities and memory areas of the SSD  10 . 
     The control unit  103  of the SSD  10  manages seven kinds of memory capacities  104   a  to  104   g,  which are shown in  FIG. 4 . 
     The memory capacity  104   a  is NAND Capacity, and is a maximum memory capacity using the memory areas of all NAND memories  104 A to  104 H. Specifically, the memory capacity  104   a  is the sum of the physical memory capacities of the NAND memories  104 A to  104 H. For example, if the memory capacity of each of the NAND memories  104 A to  104 H is 16 GB, the memory capacity  104   a  is 128 GB. The memory capacity  104   a,  i.e. the NAND Capacity, is given by, e.g. NAND structure information of a manufacture information write command of a UART (Universal Asynchronous Receiver Transmitter). 
     The memory capacity  104   b  is Max Logical Capacity, and is a maximum memory capacity that is accessible by a logical block address (LBA). 
     The memory capacity  104   c  is a S.M.A.R.T. log area start LBA, and is provided in order to divide the memory capacity  104   b  and the memory capacity  104   d  which will be described below. The S.M.A.R.T. log area start LBA indicates a first LBA of the memory area which stores log data. 
     The memory capacity  104   d  is Vender Native Capacity, and is a maximum memory capacity which is given as a user use area. The memory capacity  104   d  is given by, e.g. initial Identify Device data of an ATA specific command. In addition, the memory capacity  104   d  is determined by the manufacturer (Vender) at the time of design of the SSD  10  on the basis of the IDEMA (The International Disk Drive Equipment and Materials Association) standard, and is expressed by the following equation: 
       LBA=97,696,368+(1,953,504×((Capacity in GB)−50)). 
     The memory capacity  104   e  is OEM Native Capacity, and is a memory capacity which is determined at the time of manufacture by a request of an OEM (Original Equipment Manufacturer). The memory capacity  104   e  is given by, e.g. unique information write of an ATA specific command. In addition, the memory capacity  104   e  is a value which is returned by a Device Configuration Identify command when Device Configuration Overlay Feature Set is supported. 
     The memory capacity  104   f  is Native Capacity, and its initial value is equal to the memory capacity  104   e.  This value can be varied by a Device Configuration Set command when Feature Set is supported. In addition, the memory capacity  104   f  is a value which is returned by a Read Native Max Address (EXT) command. 
     The memory capacity  104   g  is Current Capacity and is a memory capacity during use by the user, and the initial value is equal to the memory capacity  104   f.  This value can be varied by a SET Max Address command. This value is returned by Word 61:60, and Word 103:100 of an Identify Device command. 
     The memory areas of the SSD  10  are present between the memory capacities  104   a  to  104   g.    
     The memory area between the memory capacities  104   a  and  104   b  stores management data (management information)  107   a  for operating the SSD  10 , and a logical/physical table  108   a  for converting each logical block address LBA to a physical address corresponding to a sector which is a memory unit of the NAND memory,  104 A to  104 H. The logical/physical table  108   a  indicates the correspondency between the logical block addresses and the physical addresses. Each of the management data  107   a  and logical/physical table  108  is data which is recorded in fixed areas in the NAND memories  104 A to  104 H. The LBA is not allocated to each of the management data  107   a  and logical/physical table  108   a.  Thus, each of the management data  107   a  and logical/physical table  108   a  cannot be accessed, with the LBA being used as a key. The control unit  103  has a fixed access path for accessing each of the management data  107   a  and logical/physical table  108   a,  and executes access to each of the management data  107   a  and logical/physical table  108   a  via the fixed access path. 
     The memory area between the memory capacity  104   b  and memory capacity  104   c  stores S.M.A.R.T. (Self-Monitoring Analysis and Reporting Technology) log data  107   b.  The S.M.A.R.T. log data  107   b  includes, for instance, various statistical information such as temperature information, in addition to event log data. The LBA, which is allocated to the S.M.A.R.T. log data  107   b,  is locally used in order for firmware, which is executed in the control unit  103 , to access the S.M.A.R.T. log data  107   b.  The firmware, which is executed in the control unit  103 , can access the S.M.A.R.T. log data  107   b  by using the LBA as a key. However, the host apparatus  8  cannot access the S.M.A.R.T. log data  107   b  by an ordinary read or write command. 
     In the present embodiment, two kinds of statistical information, namely, lifetime statistical information and monthly statistical information, are used. The lifetime statistical information is information which is collected over the lifetime. On the other hand, the monthly statistical information is statistical information which is collected in every predetermined time period, and statistical information items corresponding to plural time periods are stored in different memory areas. The control unit  103  controls a write operation, a read operation and an erase operation of the NAND memory (NAND memories  104 A to  104 H), generates, in every predetermined time period, statistical information (monthly statistical information) relating to the write operation, read operation and erase operation of the NAND memory, and stores statistical information items relating to plural time periods (monthly statistical information of plural time periods), which have time lengths each corresponding to the predetermined time period, in memory areas between the memory capacities  104   b  and  104   c.  The monthly statistical information is a statistical amount which is obtained by totaling operation conditions of the SSD  10  in every time period, and includes, for example, information relating to each of the numbers of times of write operations, read operations and erase operations of the NAND memory, which are executed in the predetermined time period. Specifically, the monthly statistical Information indicates the number of write commands and the number of read commands, which are received from the information processing apparatus main body  2  in the predetermined time period, and the number of blocks in the NAND memory, which are erased in the predetermined time period. 
     In the present embodiment, monthly statistical information of the past nine months (or five months) from the present time point is stored. Specifically, the memory area between the memory capacities  104   b  and  104   c  is provided with nine monthly statistical data memory areas for storing nine sets of monthly statistical information. The nine monthly statistical data memory areas store monthly statistical information corresponding to a time period one month before, monthly statistical information corresponding to a time period two months before, monthly statistical information corresponding to a time period three months before, monthly statistical information corresponding to a time period four months before, monthly statistical information corresponding to a time period five months before, monthly statistical information corresponding to a time period six months before, monthly statistical information corresponding to a time period seven months before, monthly statistical information corresponding to a time period eight months before, and monthly statistical information corresponding to a time period nine months before. 
     Further, the control unit  103  generates lifetime statistical information relating to the write operations, read operations and erase operations of the NAND memory, which are executed during the time period from the first activation of the SSD  10  up to the present time point, and stores the generated lifetime statistical information in the memory area between the memory capacities  104   b  and  104   c.  The lifetime statistical information is stored in a memory area different from the area in which the monthly statistical information is stored. The lifetime statistical information includes, for example, in addition to temperature statistical information, information relating to the total number of times of each of the write operation, read operation and erase operation of the NAND memory, which are executed from the first activation of the SSD  10  up to the present time point. Specifically, the lifetime statistical information indicates the number of write commands and the number of read commands, which are received from the information processing apparatus main body  2  during the time period from the first activation to the present time point, and the number of blocks in the NAND memory, which are erased during the time period from the first activation to the present time point. 
     A non-use memory area having a memory capacity of, e.g. 2 MB is set in the memory area between the memory capacities  104   c  and  104   d.  The reason for this is that the minimum memory unit of the LBA is 8 sectors, which is a memory unit corresponding to 4 KB (a large memory unit is 1 MB), whereas the actual minimum recording unit of data is 1 sector as a matter of course, and thus the S.M.A.R.T. log data  107   b  and the data recorded in the memory area equal to or lower than the memory capacity  104   d  are independently handled by providing an empty memory area with a memory capacity of 1 MB or more. 
     The memory area between the memory capacity  104   d  and  104   e  is a non-use area, and the memory capacity  104   d  and  104   e  have the same value except for a particular case. 
     The memory area between the memory capacities  104   e  and  104   f  is a memory area which is used by the OEM. As described above, the unique information  107   e,  which is determined by the request of the OEM, is written in this memory area. 
     The memory area between the memory capacities  104   f  and  104   g  is a memory area which is used by the OEM or the user. Data write is executed in this memory area by the setting of the OEM or user. 
     The memory area of the memory capacity  104   g  is a memory area which is used by the user, and data write is executed in this memory area by the setting of the user. 
     The memory capacities  104   a  to  104   g  satisfy a relationship which is expressed by the following formula: 
       memory capacity 104a&gt;memory capacity 104b&gt;memory capacity 104c&gt;memory capacity 104d≧memory capacity 104e≧memory capacity 104f≧memory capacity 104g. 
     At the time of shipment from the manufacturer (Vender), the memory capacities  104   d  to  104   g  have the same value. 
     &lt;Structure of NAND Memory&gt; 
       FIG. 5  schematically shows the structure of the NAND memory which is used in the present embodiment. Since the NAND memories  104 A to  104 H have the same function and structure, a description is given of the NAND memory  104 A. The numbers, which are added to the left sides of clusters  1041  and sectors  1042 , indicate cluster numbers and sector numbers. 
     The NAND memory  104 A is composed of a plurality of blocks (a plurality of erase blocks)  1040 . Each block  1040  is composed of a plurality of clusters, e.g. 1024 clusters  1041 . Each cluster  1041  is composed of a predetermined number of sectors, e.g. eight sectors  1042 . In the case where each cluster is composed of eight sectors, the data size of each cluster is 4 KB. In the present embodiment, a cluster having a data size of 1 MB is also usable. The data read/write is executed in units of a cluster (in units of a predetermined number of sectors). 
     &lt;Structure of Statistical Information&gt; 
       FIG. 6  shows examples of statistical information included in the S.M.A.R.T. log data, the items of the statistical information, and the timings of update. In the SSD  10  according to the present embodiment, as described above, monthly statistical information (hereinafter referred to as “monthly information”) based on the operation condition of the SSD  10 , apart from the lifetime statistical information collected over the lifetime from the first activation time, is stored in the S.M.A.R.T. log data  107   b  shown in  FIG. 4 . 
     This monthly information is statistical information which is indicative of the statistical amount relating to the operation condition of the SSD  10 . The control unit  103  generates, in every predetermined time period, statistical information (e.g. the number of times of execution) relating to a plurality of predetermined items (e.g. read operation, write operation, erase operation, and wear leveling operation, etc.), and stores the generated statistical information in the memory areas of the NAND memories  104 A to  104 H. The predetermined time period is a time period which is obtained by dividing the working time of the SSD  10  by a predetermined time. The predetermined time period is, for instance, a period corresponding to one month. Whether the time of one month has passed or not may not always be determined on the basis of the calendar. For example, if the total working time of the SSD  10  has reached 160 hours, it may be determined that the period corresponding to one month has passed. This determination method is based, for example, on the presupposition that the working time of the SSD  10  (the period in which the SSD  10  is powered on) is eight hours per day, and the user uses the SSD  10  for 20 days per month. 
     In the description below, it is assumed that the monthly information is generated and stored each time the value of an internal counter provided in the control unit  103  reaches a preset value (e.g. a count value corresponding to one month=160 hours). The internal counter counts the time during which the SSD  10  is powered on. By using such an internal counter, the monthly information can be generated and stored, even without providing a clock, such as a read-time clock, in the SSD  10 . 
     The monthly information is composed of, for instance, statistical information relating to a host-side interface, statistical information relating to a data manager, statistical information relating to a security manager, statistical information relating to an ATA driver, and statistical information relating to a NAND driver. Each statistical information is composed of 256 records each comprising 16-byte data. 
     The statistical information of the host-side interface is, for instance, the number of received read commands, and the number of received write commands. The number of received read commands is indicative of the number of times of reception of the read command from the host apparatus  8  during a predetermined time period. The number of received write commands is indicative of the number of times of reception of the write command from the host apparatus  8  during a predetermined time period. The number of received read commands and the number of received write commands are incremented by (+1), respectively, at update timings which correspond to the time of reception of the read command and the time of reception of the write command. 
     The statistical information of the data manager is, for instance, the maximum number of times of erase of the NAND memory, and the number of erased blocks. The maximum number of times of erase is indicative of a maximum erase number in all blocks of the NAND memory. The number of erased blocks is indicative of the number of blocks which are erased during a predetermined time period. The update timing of the maximum number of times of erase is the time of block erase. At the time of block erase, it is determined whether the maximum erase number in all blocks is greater than the current value of the maximum number of times of erase. If the maximum erase number in all blocks is greater than the current value of the maximum number of times of erase, the maximum number of times of erase is incremented by +1. The update timing of the number of erase blocks is the time of block erase. At the time of block erase, the number of erase blocks is incremented by +1. The statistical information of the data manager may include a total read data amount (the total number of sectors which are read) during a predetermined time period, and a total write data amount (the total number of sectors which are written) during a predetermined time period. 
     The statistical information of the security manager is, for instance, the number of times of user password setting, and the number of times of firmware download. The number of times of user password setting is indicative of the number of times of setting of the user password during a predetermined time period. The number of times of firmware download is indicative of the number of times of download of firmware during a predetermined time period. The number of times of user password setting is incremented by (+1) at an update timing which corresponds to the time of user password setting. In addition, the number of times of firmware download is incremented by (+1) at an update timing which corresponds to the time of firmware update. 
     The statistical information of the ATA driver is, for instance, the number of times of hardware reset, and the number of times of software reset. The number of times of hardware reset is incremented by (+1) at an update timing which corresponds to the time of hardware reset. The number of times of software reset is incremented by (+1) at an update timing which corresponds to the time of software reset. 
     The statistical information of the NAND driver is, for instance, the total amount of NAND write and the number of times of erase failure. The total amount of NAND write is added to the current value at an update timing which corresponds to the time of NAND write. The number of times of erase failure is incremented by (+1) at an update timing which corresponds to the time of erase failure. 
     &lt;Operation&gt; 
       FIG. 7  schematically shows an example of the content of stored monthly information, and  FIG. 8  is a flow chart showing the procedure of storing monthly information. The operation of storing monthly information will now be described with reference to the drawings. A description is given of the procedure of creating monthly information in every month with respect to the number of received read commands, which is the above-described statistical information of the host-side interface. The matrix of numerical values shown in  FIG. 7  indicates monthly information which is stored in units of a month in the NAND memory,  104 A to  104 H. In  FIG. 7 , it is assumed that the monthly information for five months is stored. In the NAND memory, there are prepared five monthly information memory areas which correspond, respectively, to monthly information one month before, monthly information two months before, monthly information three months before, monthly information four months before, and monthly information five or more months before. 
     If the SSD  10  starts operating on March 1 (step S 1 ), the control unit  103  increments the number of received read commands (step S 3 ) each time a read command is received (step S 2 : Yes). When April 1, which is one month after, and is a time of totaling, has come (step S 4 : Yes), the number of received read commands at that time point, for instance, “10”, is copied and stored as monthly information in the area corresponding to one month before (step S 5 ). 
     Specifically, the control unit  103  starts monitoring the number of received read commands from March 1, and counts the number of read commands that are received from the host apparatus  8 . When April 1 has come, to be more specific, if the total working time of the SSD  10  from the first activation time (March 1) has reached 160 hours, the control unit  103  acquires a count value of the number of received read commands, generates monthly information including this count value (“10”), and stores the generated monthly information in the memory area which is prepared in the NAND memory and which corresponds to monthly information one month before. 
     The control unit  103  repeats the above-described process of steps S 2  to S 4 . If May 1, which is two months after, has come (S 4 : Yes), the control unit  103  stores the number of received read commands, e.g. “30”, as monthly information in the area corresponding to one month before, and stores the number of received read commands, “10”, in the area corresponding to two months before (step S 5 ). 
     Specifically, the control unit  103  starts monitoring the number of received read commands from March 1, and counts the number of read commands that are received from the host apparatus  8 . When May 1 has come, to be more specific, if the total working time of the SSD  10  from the previous generation of monthly information has reached 160 hours, the control unit  103  acquires once again a count value of the number of received read commands, and generates monthly information including this count value (“30”). The control unit  103  shifts the monthly information (“10”), which is already stored in the memory area corresponding to monthly information one month before, to the memory area corresponding to monthly information two months before, and stores the generated monthly information (“30”) in the memory area corresponding to monthly information one month before. 
     Subsequently, the above-described operation is repeated at each time of totaling, that is, at predetermined time intervals. 
     As described above, the monthly information is stored in the NAND memory,  104 A to  104 H, in a time-sequential manner at the time of totaling, and thereby the operation history in each predetermined time interval can easily and quickly be understood with respect to the number of received read commands. Further, the stored monthly information is read out of the SSD  10  by using the application which operates on the basis of the operation of the information processing apparatus  1 , and an arithmetic operation is executed by the CPU  115  of the information processing apparatus  1 . Thereby, creation of data, such as histograms, can easily be made, and an output, such as screen display, can easily be performed. As regards the creation of monthly information, the description has been given of the case in which the predetermined period is invariable. Alternatively, the interval between the previous time of totaling and the time of next totaling may be adjusted in accordance with the operation condition of the SSD  10 . 
     Besides, the monthly information, which is stored in the NAND memory,  104 A to  104 H, may be read out of the SSD  10  by a device which is connected to the outside via the information processing apparatus  1 . In this case, the operation history of the SSD  10  in the predetermined time period can be understood in the state in which the SSD  10  is accommodated in the main body of the information processing apparatus  1 . 
     In the above-described example of the monthly information acquisition method, the description has been given of the case in which the count value of the number of received read commands is not cleared in every month. Alternatively, the count value of the number of received read commands may be cleared in every month. 
       FIG. 9  schematically shows another example of the content of stored monthly information, and  FIG. 10  is a flow chart showing another example of the procedure of storing monthly information. 
     If the SSD  10  starts operating on March 1 (step S 11 ), the control unit  103  increments the number of received read commands (step S 13 ) each time a read command is received (step S 12 : Yes). When April 1, which is one month after, and is a time of totaling, has come (step S 14 : Yes), the number of received read commands at that time point, for instance, “10”, is copied and stored as monthly information in the area corresponding to one month before (step S 15 ). Subsequently, the control unit  103  clears the total value which is obtained during the period from the previous time of totaling to the present time of totaling (step S 16 ). 
     Specifically, the control unit  103  starts monitoring the number of received read commands from March 1, and counts the number of read commands that are received from the host apparatus  8 . When April 1 has come, to be more specific, if the total working time of the SSD  10  from the first activation time (March 1) has reached 160 hours, the control unit  103  acquires a count value of the number of received read commands, generates monthly information including this count value (“10”), and stores the generated monthly information in the memory area which is prepared in the NAND memory and which corresponds to monthly information one month before. In addition, the control unit  103  clears the count value of the number of received read commands. 
     The control unit  103  repeats the above-described process of steps S 12  to S 14 . When May 1, which is two months after, has come (S 14 : Yes), the control unit  103  stores the number of received read commands, e.g. “20”, as monthly information in the area corresponding to one month before, and stores the number of received read commands, “10”, in the area corresponding to two months before (step S 15 ). In addition, the control unit  103  clears the current total value “20” of the number of received read commands (step S 16 ). 
     Specifically, the control unit  103  starts monitoring, once again, the number of received read commands from April 1, and counts the number of read commands that are received from the host apparatus  8  after April 1. When May 1 has come, to be more specific, if the total working time of the SSD  10  from the previous generation of monthly information has reached 160 hours, the control unit  103  acquires once again a count value of the number of received read commands, and generates monthly information including this count value (“20”). The control unit  103  shifts the monthly information (“10”), which is already stored in the memory area corresponding to monthly information one month before, to the memory area corresponding to monthly information two months before, and stores the generated monthly information (“20”) in the memory area corresponding to monthly information one month before. Then, the control unit  103  clears the count value of the number of received read commands. 
     Subsequently, the above-described operation is repeated at each time of totaling, that is, at predetermined time intervals. As a result, the monthly information of the recent five months is stored in the NAND memory. 
     The memory area corresponding to the monthly information five months before may store only the number of received read commands, which corresponds to the time period of one month which is five months before. Alternatively, as shown in  FIG. 9 , the memory area corresponding to the monthly information five months before may store the number of received read commands during the entire time period of five months or more before. 
     As has been described above, after the monthly information is stored in the NAND memory,  104 A to  104 H, at each time of totaling, the total value (count value) of the number of received read commands is cleared. Thereby, it becomes possible to easily understand how many read commands have been received in one month, which is a predetermined time period. In the above-described example, only the number of received read commands has been described. Actually, monthly information including statistical amounts relating to various object items of monitoring, which have been described with reference to  FIG. 6 , is stored in the NAND memory in every predetermined time period. In this way, in the present embodiment, the statistical amounts relating to various object items of monitoring are generated as monthly information in every predetermined time period, and the monthly information corresponding to a plurality of periods (e.g. five months) each having the same time period is individually stored in the NAND memory. Thereby, at a time of diagnosing a fault of the SSD  10 , for example, it is possible to quickly understand how the SSD  10  has been used immediately before the fault, and to improve the efficiency in analysis work. 
     The various modules of the systems described herein can be implemented as software applications, hardware and/or software modules, or components on one or more computers, such as servers. While the various modules are illustrated separately, they may share some or all of the same underlying logic or code. 
     While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.