Patent Publication Number: US-2009240905-A1

Title: Real-time backup method for single storage medium

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a real-time backup method and in particular to a real-time backup method for single storage medium. 
     2. Description of the Prior Art 
     A conventional real-time backup method for single storage medium, referring to  FIG. 1 , includes a storage medium  10  (e.g. a hard disk) partitioned into two unit blocks  11   a,    11   b.  For example, data are respectively written into strip blocks  111   a,    112   a  and strip blocks  111   b,    112   b  of two unit blocks  11   a,    11   b  at the same time. The data in strip blocks  111   b,    112   b  can be read instead of that in strip blocks  111   a,    112   a  to prevent from reading failure. The conventional method utilizes only half storage medium volume that wastes the storage for the situation of only few backup data. 
     SUMMARY OF THE INVENTION 
     The objective of the present invention to provide a real-time backup method for single storage medium which partitions a single storage medium into multiple logic units, and assigns each logic unit as a backup logic unit or a normal storage logic unit, and partitions the backup logic unit into two or more unit blocks. 
     Data with real-time backup demand are simultaneously written into two strip blocks belonging respectively to two unit blocks in the backup logic unit to achieve real-time backup function. 
     When the usage rate of the two unit blocks is full, another two unit blocks are sequentially adopted for backup. In similar way, when the usage rate of the backup logic unit is full, another logic unit is sequentially adopted for storing data, and therefore the usage rate of the storage medium is enhanced. 
     Other advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings, which are set forth by way of illustration and example, to certainly embody the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing aspects and many of the accompanying advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a schematic diagram showing conventional real-time backup data. 
         FIG. 2  is a flow chart showing a real-time backup method for single storage medium according to one embodiment of the present invention. 
         FIG. 3 ,  FIG. 4 , and  FIG. 5  are schematic diagrams showing real-time backup data for single storage medium according to various embodiments of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A real-time backup method for single storage medium according to the present invention is disclosed in the  FIG. 2 . As shown in the figure, a storage medium in the present invention is partitioned into multiple logic units, and each logic unit is designated as a backup logic unit or a normal storage logic unit (step S 10 ). The backup logic unit is partitioned into two or more unit blocks (Step S 20 ). The process of real-time backup should be determined to proceed or not (step S 30 )—it depends what the data is with or without backup demand. If “Yes”, the backup logic unit is chosen (Step S 41 ), and then two unit blocks are selected, and then the data are written into strip blocks of these two unit blocks in the backup logic unit (Step S 43 ); if “No”, the normal storage logic unit is chosen (Step S 51 ) and then the data are written into the normal storage logic unit (Step S 52 ). 
       FIG. 3  shows the first embodiment of the present invention. As shown in the figure, a storage medium  20  is partitioned into a backup logic unit  21  and a normal storage logic unit  22 , and the backup logic unit  21  is further partitioned into two unit blocks  211   a,    211   b.    
     The data with backup demand are simultaneously stored in strip blocks  2111   a,    2112   a  and  2111   b,    2112   b  of two unit blocks  211   a,    211   b  in the backup logic unit  21 , respectively, and the data without backup demand are stored in the strip block  221  in the normal storage logic unit  22 . The reading process includes reading an address from the backup logic unit  21 , selecting a unit block according to the address and reading data from the stripe block of the unit block. When the data stored in the strip blocks  2111   a,    2112   a  are corrupted, the backup data in strip blocks  2111   b,    2112   b  are available. 
       FIG. 4 . shows the second embodiment of the present invention. As shown in the figure, a storage medium  20  is partitioned into a backup logic unit  21  and a normal storage logic unit  22 , and the backup logic unit  21  is further partitioned into even numbers of unit blocks  211   a,    211   b,    212   a,    212   b,    213   a,    213   b,  and so on. 
     As the first embodiment shows, the data with backup demand are simultaneously stored in strip blocks  2111   a,    2111   b  of two unit blocks  211   a,    211   b  in the backup logic unit  21 , and the data without backup demand are written into the strip block  221  in the normal storage logic unit  22 . 
     What differs from the first embodiment is when the usage of unit blocks  211   a,    211   b  is full, the unit blocks  212   a,    212   b  may be adopted for real-time backup, and unit block  213   a,    213   b  may be sequentially adopted accordingly. The reading process includes reading an address from the backup logic unit  21 , selecting a unit block according to the address and reading data from the stripe block of the unit block. 
       FIG. 5  shows the third embodiment of the present invention. As shown in the figure, a storage medium  20  is partitioned into multiple logic units  21 ,  22 ,  23 ,  24 ,  25 ,  26 , etc., and the logic units are designated as backup logic units or normal storage logic units. 
     Those that are designated as backup logic units are further partitioned into two or more unit blocks for real-time backup, as shown in the first or second embodiment, and, in similar way, those that are designated as the normal storage logic units are sequentially adopted for normal data storage when the data storage is full. 
     While the invention is susceptible to various modifications and alternative forms, a specific example thereof has been shown in the drawings and is herein described in detail. It should be understood, however, that the invention is not to be limited to the particular form disclosed, but to the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the appended claims.