Patent Publication Number: US-7913029-B2

Title: Information recording apparatus and control method thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2007-080134, filed Mar. 26, 2007, the entire contents of which are incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     One embodiment of the invention relates to an information recording apparatus that carries out write and readout of information with respect to, for example, a disc-shaped storage medium with a large capacity, such as a hard disc, by using a semiconductor memory as a cache, and also relates to a control method of the information recording apparatus. 
     2. Description of the Related Art 
     As is well-known, a hard disc is a large-capacity and reliable information recording medium, and is widespread in many areas, for example, to be used for recording computer data, image data, audio data, and so on in recent years. In addition, the size of the hard disc has been downsized to make it mountable in a portable electronic device. 
     For the above reason, when downsizing an information recording apparatus that includes such hard disc, a semiconductor memory capable of high-speed write and high-speed readout of information is used as a cache memory for the hard disc, thereby increasing the speed required for write and readout of the information. 
     That is, the information recording apparatus of this kind carries out write and readout of information with respect to an external host device via the cache memory, and carries out transfer of information between the hard disc and the cache memory. In this manner, write and readout of information as seen from the outside is speeded up. 
     At present, it is considered to attempt to save battery energy by reducing the number of drives of the hard disc, that is, the number of writes and readouts of information with respect to the hard disc, in a manner that a non-volatile memory is included as a cache with respect to the hard disc in addition to the cache memory. Such an information recording apparatus is called an NV (non volatile)-cache compatible HDD (hard disc drive), and is standardized. 
     In the information recording apparatus including a hard disc as the information recording medium, in a case where a defect occurs in a specific region (sector) on the hard disc and the reliability of write and readout of information is extremely lowered, a substitution processing for substituting the defect region with another region on the hard disc is carried out. 
     However, in such a substitution processing, a magnetic head needs to be moved to a substituting region corresponding to the defect region when write and readout of information is carried out with respect to the hard disc. Therefore, additional time is required for such move in the write and readout of information. 
     Jpn. Pat. Appln. Publication No. 2-109151 discloses a configuration where, when data written in a battery backup RAM (random access memory) is written in a disc, a region in the RAM in which the data was failed to be written in the disc is stored is configured to be a substituting region, in a period where there is no request for write and readout from a host computer. 
    
    
     
       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 block configuration diagram showing an embodiment of the present invention to explain an outline of an information recording apparatus; 
         FIG. 2  is a view for explaining a recording region in a flash memory included in the information recording apparatus according to the same embodiment; 
         FIG. 3  is a view for explaining an example of a management table of the flash memory included in the information recording apparatus according to the same embodiment; 
         FIG. 4  is a block configuration diagram for explaining an example of a controller included in the information recording apparatus according to the same embodiment; 
         FIG. 5  is a flowchart for explaining a first example of a substitution processing operation of a defect region carried out by the information recording apparatus according to the same embodiment; 
         FIG. 6  is a flowchart for explaining a second example of a substitution processing operation of a defect region carried out by the information recording apparatus according to the same embodiment; 
         FIG. 7  is a flowchart for explaining a third example of a substitution processing operation of a defect region carried out by the information recording apparatus according to the same embodiment; and 
         FIG. 8  is a flowchart for explaining a fourth example of a substitution processing operation of a defect region carried out by the information recording apparatus according to the same embodiment. 
     
    
    
     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, an information recording apparatus has a control unit configured to control mutual transfer of information between each of a disc-shaped recording medium, a cache memory, and a non-volatile memory and the outside, control mutual transfer of information between the disc-shaped recording medium, the cache memory, and the non-volatile memory, and control to set a substituting region corresponding to a defect region generated in the disc-shaped recording medium in the non-volatile memory. 
       FIG. 1  shows an outline of an information recording apparatus  11  explained in the embodiment. As the information recording apparatus  11  which will be described here, an NV-cache compatible HDD is the target which is standardized by Non Volatile Cache Command Proposal for ATA8-ACS Revision 5, and so on. 
     The information recording apparatus  11  includes an LSI (large scale integrated) circuit  12  of one chip incorporating various kinds of circuit blocks. Further, a hard disc  13  being a disc-shaped storage medium with a large capacity, an SDRAM (synchronous dynamic random access memory)  14 , a flash memory  15 , and so on are connected to the LSI circuit  12 . 
     Of these, the SDRAM  14  functions as a buffer and is a cache memory for the hard disc  13 . However, not limited to the SDRAM, S (static) RAM, and so on, can be used, for example. In addition, the flash memory  15  is a non-volatile memory (NV-cache) functioning as a cache for the hard disc  13 . 
     Here, the LSI circuit  12  incorporates a controller  16  that works as a control unit for carrying out overall control when the information recording apparatus  11  executes various kinds of processing operations. The LSI circuit  12  incorporates a disc I/F (interface)  17  that connects the controller  16  and the hard disc  13  to be information transferable. 
     In addition, the LSI circuit  12  incorporates an SDRAM I/F  18  that connects the controller  16  and the SDRAM  14  to be information transferable, a flash memory I/F  19  that connects the controller  16  and the flash memory  15  to be information transferable, a host I/F  21  that connects the controller  16  and an external host device  20  to be information transferable, and so on. 
     The host device  20  is, for example, a PC (personal computer). When, for example, predetermined application software is executed, the host device  20  executes write and readout of information by using the information recording apparatus  11 , and can use the information recording apparatus  11  as a storing destination of the information finally obtained. 
     In a case where the write and readout of information is carried out with respect to the information recording apparatus  11  in the above manner, the host device  20  generates a command to request write of information and a command to request readout of information with respect to the information recording apparatus  11 . These commands are supplied to the controller  16  through the host I/F  21  and analyzed. 
     In this manner, the controller  16  can control the hard disc  13 , the SDRAM  14 , the flash memory  15 , and so on to carry out write of information supplied from the host device  20  and readout of information to be supplied to the host device  20 . In this case, the controller  16  enables mutual transfer of information between the hard disc  13 , the SDRAM  14 , and the flash memory  15 . 
     To be more specific, in a case where information supplied from the host device  20  is written in the hard disc  13 , the controller  16  can choose any of five paths (W 1 ) to (W 5 ) shown hereinafter as an order of writing information. 
     (W 1 ) host I/F  21 —controller  16 —disc I/F  17 —hard disc  13   
     (W 2 ) host I/F  21 —controller  16 —SDRAM I/F  18 —SDRAM  14 —SDRAM I/F  18 —controller  16 —disc I/F  17 —hard disc  13   
     (W 3 ) host I/F  21 —controller  16 —flash memory I/F  19 —flash memory  15 —flash memory I/F  19 —controller  16 —disc I/F  17 —hard disc  13   
     (W 4 ) host I/F  21 —controller  16 —SDRAM I/F  18 —SDRAM  14 —SDRAM I/F  18 —controller  16 —flash memory I/F  19 —flash memory  15 —flash memory I/F  19 —controller  16 —disc I/F  17 —hard disc  13   
     (W 5 ) host I/F  21 —controller  16 —flash memory I/F  19 —flash memory  15 —flash memory I/F  19 —controller  16 —SDRAM I/F  18 —SDRAM  14 —SDRAM I/F  18 —controller  16 —disc I/F  17 —hard disc  13   
     In addition, in a case where information is readout from the hard disc  13  to the host device  20 , the controller  16  can choose any of five paths (R 1 ) to (R 5 ) shown hereinafter as an order of reading out information. 
     (R 1 ) disc I/F  17 —controller  16 —host I/F  21 —host device  20   
     (R 2 ) disc I/F  17 —controller  16 —SDRAM I/F  18 —SDRAM  14 —SDRAM I/F  18 —controller  16 —host I/F  21 —host device  20   
     (R 3 ) disc I/F  17 —controller  16 —flash memory I/F  19 —flash memory  15 —flash memory I/F  19 —controller  16 —host I/F  21 —host device  20   
     (R 4 ) disc I/F  17 —controller  16 —SDRAM I/F  18 —SDRAM  14 —SDRAM I/F  18 —controller  16 —flash memory I/F  19 —flash memory  15 —flash memory I/F  19 —controller  16 —host I/F  21 —host device  20   
     (R 5 ) disc I/F  17 —controller  16 —flash memory I/F  19 —flash memory  15 —flash memory I/F  19 —controller  16 —SDRAM I/F  18 —SDRAM  14 —SDRAM I/F  18 —controller  16 —host I/F  21 —host device  20   
     The order of writing information and the order of reading out information described above are determined by the controller  16 , for example, in accordance with a content of instruction in a write requesting command and a readout requesting command supplied from the host device  20 , a storage location of information, free space of the SDRAM  14  and the flash memory  15 , and so on. 
     As the flash memory  15  described above, a NAND flash memory is widely used. In a case where the NAND flash memory is adopted, the speed of write and readout of information with respect to the flash memory  15  is often slower than the speed of write and readout of information with respect to the SDRAM  14 . 
     Here, of the various types of commands that are set by the above standards and can be executed by the information recording apparatus  11 , one which is necessary for describing the present embodiment will be described. A first command designates a logical block address (LBA) in which information is written in the flash memory  15  among LBAs on the hard disc  13 . 
     In addition, a second command designates an LBA to be written in the flash memory  15  in a similar manner as the first command. At the same time, the second command requests readout of information recorded in the LBA from the hard disc  13  and write of the readout information in the flash memory  15 . 
     The first and the second commands described above correspond to PI=0 and PI=1 in Add LBA(s) to NV Cache Pinned Set in the above standards. An LBA that is instructed by the host device  20  to store information in the flash memory  15  is attached with attribute information called pinned. 
     A third command designates an LBA on the hard disc  13  and requests write of information. In a case where the third command is generated from the host device  20 , the controller  16  checks whether the LBA requested for write is associated with the attribute information of pinned. In a case where the LBA is associated with the attribute information of pinned, the third command executes write in a region corresponding to the LBA requested for write in the flash memory  15 . 
     On the other hand, in a case where the LBA requested for write is not associated with the attribute information of pinned, the controller  16  arbitrarily determines whether information should be written in a region corresponding to the designated LBA in the SDRAM  14  or the flash memory  15 , or information should be written in the designated LBA in the hard disc  13 , and executes such accordingly. 
     A fourth command designates an LBA on the hard disc  13  and requests readout of information. In a case where the fourth command is generated from the host device  20 , and when a region corresponding to the designated LBA is already allocated on the flash memory  15  and it is determined that information newer than the hard disc  13  is stored in the region, the controller  16  needs to readout such information from the flash memory  15 . 
     On the other hand, in a case where there is same information in the hard disc  13  and the flash memory  15 , the controller  16  may read out the information from a region corresponding to the LBA requested for readout in the flash memory  15 , or may read out information from the designated LBA on the hard disc  13 . 
     In addition, in a case where a region corresponding to the designated LBA is already allocated in the flash memory  15  even though there exists latest data in the hard disc  13 , the controller  16  needs to read out the information from the designated LBA on the hard disc  13 . When information is read out from the hard disc  13 , the controller  16  also determines whether the information should be cached in the SDRAM  14  or in the flash memory  15 . 
     Like the third and the fourth commands described above, out of LBAs that are not associated with the attribute information of pinned among the LBAs that are requested for write and readout of information, an LBA in which information is written in a region allocated in the flash memory  15  is attached with attribute information called unpinned. 
     The LBA attached with the attribute information of pinned is called a pinned LBA, and a region in the flash memory  15  corresponding to the pinned LBA is called a pinned region. In addition, the LBA attached with the attribute information of unpinned is called an unpinned LBA, and a region in the flash memory  15  corresponding to the unpinned LBA is called an unpinned region. Therefore, as shown in  FIG. 2 , a pinned region  15   a , an unpinned region  15   b , and a remaining region  15   c  are formed in the flash memory  15 . 
     A fifth command requests to form an empty region for a designated size portion in the flash memory  15 , and is compatible with Flush NV Cache among the standards described above. In a case where the fifth command is generated from the host device  20 , the controller  16  compares size of a current empty region and size of the requested empty region in the flash memory  15 . 
     In a case where the size of the current empty region in the flash memory  15  is smaller than the size of the requested empty region, the controller  16  secures the empty region of designated size in the flash memory  15  by moving information of the designated size or more in a region corresponding to the LBA attached with the attribute information of unpinned (unpinned region  15   b ) in the flash memory  15  to the hard disc  13 . 
     In this case, the controller  16  determines information in which region among regions corresponding to the LBAs attached with the attribute information of unpinned (unpinned region  15   b ) in the flash memory  15  is moved to the hard disc  13 , that is, in which region in the flash memory  15  an empty region is formed. 
     A sixth command designates an LBA and requests resetting of the attribute information of pinned (the attribute information of the LBA is made not pinned), and is compatible with Remove LBA(s) From NV Cache Pinned Set in the standards described above. In a case where the sixth command is generated from the host device  20 , the controller  16  needs to transfer information stored in a region corresponding to the LBA designated by the sixth command in the flash memory  15  to the hard disc  13  and have the information written. However, a timing thereof is not specified in the standard described above. 
     Based on the various commands, write and readout of information with respect to the hard disc  13  are executed in the orders (W 1 ) to (W 5 ) and (R 1 ) to (R 5 ) described above. 
     There is a case where the reliability of hard disc  13  with respect to write and readout of information is extremely lowered due to the generation of a defect in a specific region (sector) due to the situation at the time of manufacturing, part deterioration, and so on. In such a case, in a current situation, a defect region generated on the hard disc  13  is handled by being substituted by another region on the hard disc  13 . 
     However, the substitution processing as described above requires operation of moving a magnetic head (not shown) for carrying out write and readout of information with respect to the hard disc  13  from an original position of carrying out write and readout to a substituting region corresponding to a defect region. Therefore, this results in an adverse effect of speeding up the speed of write and readout of information. 
     In view of the above, in the present embodiment, a substituting region corresponding to a defect region generated on the hard disc  13  is set in the flash memory  15 . Thereby, no operation of zone movement of the magnetic head, retry of rotational speed control of the hard disc  13 , and so on takes place. Thus, write and readout of information can be achieved at high speed with high reliability. 
     In this case, a region set as a substituting region in the flash memory  15  is managed as an LBA on the hard disc  13 , and attribute information showing elimination unavailable in order to prevent unintentional elimination is added to the LBA. This attribute information is written in a management table for managing an LBA together with the attribute information showing pinned and unpinned described above. 
       FIG. 3  shows an example of the management table for managing the attribute information added to each LBA. The management table is stored, for example, in the SDRAM  12  or the flash memory  15  described above. That is, the management table is associated with a beginning LBA, and size and attribute information from the beginning LBA. 
     The attribute information includes an item of pinned/unpinned showing whether the attribute information of pinned is added or the attribute information of unpinned is added to the LBA currently, and an item of elimination unavailable/elimination available showing whether the LBA is currently used as a substituting region and cannot be eliminated, or is not used as a substituting region and can be eliminated. 
       FIG. 4  shows an example of the controller  16  described above. The controller  16  has a command analysis part  16   a  which decodes and analyzes a command supplied from the host device  20 . By the analysis result of this command analysis part  16   a , software in an architecture memory  16   b  is identified, and an operation procedure is set in a sequence controller  16   c.    
     The sequence controller  16   c  controls a flow of information via an I/F and a bus controller  16   d . For example, when write and readout of information are carried out, a media selection part  16   e  identifies the hard disc  13 , the SDRAM  14 , or the flash memory  15 , and also an address control part  16   f  identifies a write address and a readout address. 
     At the time of write of information, a write processing part  16   g  executes transfer processing or the like of write information. In addition, at the time of readout of information, a readout processing part  16   h  executes transfer processing or the like of readout information. 
     Further, the controller  16  is provided with an erasing processing part  16   i . This erasing processing part  16   i  executes erasing processing of information recorded in the SDRAM  14  and the flash memory  15 . The erasing processing part  16   i  can also execute erasing processing of information recorded in the hard disc  13 . 
     In addition, the controller  16  is provided with an address management part  16   j . This address management part  16   j  collectively manages addresses of recorded regions, non-recorded regions, and so on of the SDRAM  14 , the flash memory  15 , and the hard disc  13 . 
     Further, the controller  16  is provided with a state determination part  16   k . The state determination part  16   k  monitors a rotating state of the hard disc  13 , a state of remaining capacity of the hard disc  13 , the SDRAM  14 , and the flash memory  15 , and so on. 
     In addition, the controller  16  is provided with a substitution processing part  16   l . The substitution processing part  16   l  manages the substitution processing that sets a substituting region with respect to a defect region generated on the hard disc  13  in the flash memory  15 , and also controls write and rewrite of the management table described above. 
     Here, each of  FIGS. 5 to 8  shows an example of a processing operation to set a substituting region for a defect region in the flash memory  15  when the defect region is generated on the hard disc  13 . First,  FIG. 5  shows a case where the processing is started (step S 5   a ), and readout of information from the hard disc  13  is requested based on the second command from the host device  20  in step S 5   b.    
     In this case, in step S 5   c , the controller  16  discriminates whether information was readout or not from the LBA on the hard disc  13  designated by the second command within a range of the predetermined number of times of retrying set in advance. 
     In a case where it is determined that the information was readout (YES), the controller  16  writes the information read out from the hard disc  13  in the region in the flash memory  15  allocated corresponding to the LBA designated by the second command and adds attribute information of pinned and elimination available to the designated LBA in step S 5   d . Then, the processing is terminated (step S 5   f ). 
     In addition, in a case where it is determined that information was not read out from the hard disc  13  within the range of the predetermined number of times of retrying in the above step S 5   c  (NO), the controller  16  obtains information of the LBA designated by the second command on the hard disc  13  by retrying for more than the predetermined number of times of retrying described above, and carrying out other processing set in advance such as interpolation processing in step S 5   e . Then, the controller  16  writes the information thus obtained in a region in the flash memory  15  allocated corresponding to the LBA designated by the second command, adds the attribute information of pinned and elimination unavailable to the designated LBA, and terminates the processing (step S 5   f ). 
       FIG. 6  shows a case where processing is started (step S 6   a ), and readout of information from the hard disc  13  is requested based on the fourth command described above from the host device  20  in step S 6   b.    
     In this case, the controller  16  discriminates whether information was readout or not from the LBA on the hard disc  13  designated by the fourth command within the range of the predetermined number of times of retrying set in advance in step S 6   c . In a case where it is determined that the information was read out (YES), the processing is terminated (step S 6   e ). 
     In a case where the controller  16  controls the information read out from the hard disc  13  to be written in the region in the flash memory  15  allocated corresponding to the LBA designated by the fourth command, the attribute information of elimination available is added to the designated LBA, the attribute information of unpinned is added to the LBA to which the attribute information of pinned is not added among the designated LBAs, and then the processing is terminated (step S 6   e ). 
     In addition, in a case where it is determined that the information was not read out from the hard disc  13  within the range of the predetermined number of times of retrying in the above step S 6   c  (NO), the controller  16  obtains information of the LBA on the hard disc  13  designated by the fourth command by retrying for more than the predetermined number of times of retrying described above, and carrying out other processing set in advance such as interpolation processing in step S 6   d.    
     Thereafter, the controller  16  writes the obtained information in the region in the flash memory  15  allocated corresponding to the LBA designated by the fourth command, and adds the attribute information of elimination unavailable to the designated LBA. Together therewith, the controller  16  adds the attribute information of unpinned to the LBA to which the attribute information of pinned is not added among the designated LBAs, and terminates the processing (step S 6   e ). 
       FIG. 7  shows a case where processing is started (step S 7   a ), and write of information from the SDRAM  14  to the hard disc  13  is requested in step S 7   b . This request for write is achieved, for example, in a case where the controller  16  controls information from the host device  20  to be written in the hard disc  13  via the SDRAM  14  in the third command described above. 
     In this case, the controller  16  determines whether information was written in the LBA on the hard disc  13  designated by the host device  20  within the range of the predetermined number of times of retrying set in advance in step S 7   c . In a case where the controller  16  determines the information was written (YES), the processing is terminated (step S 7   e ). 
     In a case where the information written in the hard disc  13  by the controller  16  is controlled to be also written in the region in the flash memory  15  allocated corresponding to the LBA designated by the host device  20 , the attribute information of elimination available is added to the designated LBA, the attribute information of unpinned is added to the LBA to which the attribute information of pinned is not added among the designated LBAs, and then the processing is terminated (step S 7   e ). 
     In addition, in a case where it is determined that information was not written in the hard disc  13  within the range of the predetermined number of times of retrying in the above step S 7   c  (NO), the controller  16  writes the information which could not be written in the hard disc  13  in the region in the flash memory  15  allocated corresponding to the LBA designated by the host device  20  in step S 7   d.    
     Thereafter, the controller  16  adds the attribute information of elimination unavailable to the LBA designated by the host device  20 , adds the attribute information of unpinned to the LBA to which the attribute information of pinned is not added among the designated LBAs, and then terminates the processing (step S 7   e ). 
     Next,  FIG. 8  shows a case where processing is started (step S 8   a ), and write of information from the flash memory  15  to the hard disc  13  is requested in step S 8   b . This request for write is achieved, for example, in a case where the controller  16  controls information from the host device  20  to be written in the hard disc  13  via the SDRAM  14  and the flash memory  15  in a state where the third command is generated under generation of the first command described above. 
     In this case, the controller  16  determines whether information was written in the LBA on the hard disc  13  designated by the host device  20  within the range of the predetermined number of times of retrying set in advance in step S 8   c.    
     In a case where the controller  16  determines the information was written (YES), the controller  16  adds the attribute information of pinned and elimination available to an LBA corresponding to the region in the flash memory  15  where the information written in the hard disc  13  is stored in step S 8   d , and then terminates the processing (step S 8   f ). 
     In addition, in a case where it is determined that the information was not written in the hard disc  13  in the range of the predetermined number of times of retrying in the above step S 8   c  (NO), the controller  16  adds the attribute information of pinned and elimination unavailable to an LBA corresponding to a region in the flash memory  15  in which the information not written in the hard disc  13  is stored in step S 8   e , and terminates the processing (step S 8   f ). 
     According to the embodiment described above, a substituting region with respect to a defect region generated on the hard disc  13  is configured to be able to be set in the flash memory  15 . Therefore, at the time of write and readout of information with respect to the hard disc  13 , moving of the magnetic head to a substituting region, operation of controlling again the rotational speed of the hard disc  13 , and so on become unnecessary, and write and readout of information can be achieved at high speed with high reliability. 
     In addition, an LBA of a defect region on the hard disc  13 , that is, an LBA of a region substituted by the flash memory  15  is added with the attributable information of elimination unavailable on the management table of the LBA. Therefore, invalidation of substitution processing due to careless elimination can reliably be prevented. 
     Further, in a case where requests of write and readout of information with respect to the hard disc  13  is generated from the host device  20 , special processing in which a defect region in the hard disc  13  is substituted by the flash memory  15  is not necessary, and write and readout of information can be performed by using a control routine of a normal NV-cache-compatible HDD as it is. 
     To be more specific, for example, it is assumed that a request for readout of a region from an LBA  390  to an LBA  410  is generated from the host device  20  in a state where an LBA  400  on the hard disc  13  becomes a defect region and is substituted by the flash memory  15 . 
     In this case, the controller  16  can know that information of the LBA  400  exists in the flash memory  15  from the management table. In addition, the controller  16  can also know that information other than the information of the LBA  400  does not exist on the flash memory  15 . 
     For this reason, the controller  16  carries out readout of information of regions from LBAs  390  to  399  and  401  to  410  with respect to the hard disc  13 , and controls the readout information to be stored in the SDRAM  14 . Thereafter, the controller  16  reads out information of the LBA  400  from the flash memory  15  and controls the readout information to be stored in the SDRAM  14 . Then, the controller  16  connects pieces of information stored in the SDRAM  14  and connects such pieces of information in an order of LBAs  390  to  410 , and controls the information to be transferred to the host device  20 . 
     The control routine of in readout, as described above, is a normal readout routine that is executed as long as the information of the LBA  400  is found to exist in the flash memory  15  by referring to the management table regardless of whether the LBA  400  is a substitute region or not. 
     Further, if attribute information showing that information on the flash memory  15  is the latest is added to the management table, processing of readout of information is sped up even more effectively. 
     When a defect region on the hard disc  13  is substituted by the flash memory  15 , precautions as described below are necessary with respect to the management table. First, with respect to an LBA to which the attribute information of unpinned and elimination unavailable is added, information of the flash memory  15  corresponding to the LBA needs to be excluded from an elimination target in order not to create an empty region by moving the information to the hard disc  13 , even when the fifth command described above is generated. 
     In addition, with respect to an LBA to which the attribute information of pinned and elimination unavailable is added, the attribute information is changed in a manner that pinned is changed to unpinned and elimination unavailable is succeeded as it is in a case where the sixth command described above is generated. 
     Further, in a case where a situation that requires a large amount of regions becomes necessary in the flash memory  15 , such as securing a large amount of the pinned region  15   a  in the flash memory  15 , is generated, information substituted by the flash memory  15  may be substituted by regions other than a defect region on the hard disc  13 . In this case, attribute information of a target LBA is ignored even when the attribute information is that of elimination unavailable, or rewritten to elimination available. 
     In addition, the predetermined number of times of retrying set in advance, which is a threshold value for determining whether write and readout of information were carried out properly, for example, is a value independently set by each manufacturer by taking into account performance, safety, and so on of the hard disc  13 . 
     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.