Abstract:
This present invention is a disk order examining system for a dual-host redundant storage device and method thereof, implementing in a dual-host redundant storage device with a master controller and a slave controller. The invention is to examine if the linkage orders of disks to the master controller are the same as those to the slave controller by sequentially writing random values into each disk of a disk concatenation, and then reading out to discriminate their sequence.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority to Taiwan Application Serial Number 97112191, filed Apr. 3, 2008, which is herein incorporated by reference. 
       BACKGROUND 
       [0002]    1. Field of Invention 
         [0003]    The present invention relates to a disk order examining system for a dual-host redundant storage device and method thereof. More particularly, the present invention relates to a system and method for determining the linking orders of disks in a dual-host redundant storage device. 
         [0004]    2. Description of Related Art 
         [0005]    Concatenation or Spanning of disks is a popular method for combining multiple physical disk drives into a single virtual disk. Concatenation may be thought of as the reverse of partitioning. Whereas partitioning takes one physical drive and creates two or more logical drives, JBOD uses two or more physical drives to create one logical drive. Concatenation is sometimes used to turn several odd-sized drives into one larger useful drive. For example, JBOD could combine 3 GB, 15 GB, 5.5 GB, and 12 GB drives into a logical drive at 35.5 GB, which is often more useful than the individual drives separately. Though, the controller of JBOD treats each drive as a stand-alone disk and each drive is an independent logical drive, JBOD does not provide data redundancy. 
         [0006]    Therefore, if the data storage should be ensured, JBOD is applied in a dual-host redundant storage device with a master controller and a slave controller of a mutual backing up function. That is, the multiple disks are linked to the master controller and the slave controller in respective orders to form a JBOD. One disk after another of the multiple disks are linked to the master controller with one linking order, and also linked to the slave controller with another linking order. If the linking order of one of the disks to the master controller is not consistent with that to the slave controller, errors occur when data is accessed. Therefore the master controller and the slave controller cannot provide a mutual backing up function under this condition. 
       SUMMARY 
       [0007]    For this reason, this invention provides a disk order examining system for a dual-host redundant storage device and method thereof, applied in a storage device with a master controller and a slave controller. The master controller sequentially writes random numbers into every disk in the disk concatenation, and the slave controller then sequentially reads out the random numbers from the disks in the disk concatenation. By comparing the orders of those two random number sequences, the system determines whether the linking order of the disks to the master controller is consistent with the linking order of the disks to the slave controller or not. 
         [0008]    The linking order examining technique of this invention is implemented with the disks in the disk concatenation linked to the master controller as a first configuration. Therefore, the random numbers written into the disks are written in a number sequence in the first configuration order. And the disks in the disk concatenation also link to the slave controller as a second configuration. Therefore, the random numbers read out from the disks is the number sequence in the second configuration order. Then, by comparing the random number sequence in the second configuration order with the random number sequence in the first configuration order, the system can determine whether the linking order of the disks to the master controller is consistent with the linking order of the disks to the slave controller or not. 
         [0009]    The invention provides a disk order examining system for a dual-host redundant storage device, comprising: a disk concatenation having a plurality of disks for data access; a master controller linking to the disks of the disk concatenation in a first configuration and accessing data to the disk concatenation; a slave controller linking to the disks of the disk concatenation in a second configuration and accessing data to the disk concatenation for backing up the master controller; a data write-in module disposed in the master controller, generating a plurality of random numbers and writing the random numbers into the disks in sequence; and an examining module disposed in the slave controller, reading out the random numbers from the disks and determining whether the first configuration is consistent with the second configuration or not. 
         [0010]    The invention provides a disk order examining method for a dual-host redundant storage device, comprising following steps: (a) generating a plurality of random numbers by a master controller; (b) writing the random numbers in a first configuration order into a disk concatenation by the master controller; (c) sending the random numbers to a slave controller; (d) reading out the random numbers in a second configuration order from the disk concatenation by the slave controller; and (e) determining if the second configuration is consistent with the first configuration. 
         [0011]    It is to be understood that both the foregoing general description and the following detailed description are by examples, and are intended to provide further explanation of the invention as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The invention can be more fully understood by reading the following detailed description of the embodiment, with reference made to the accompanying drawings as follows: 
           [0013]      FIG. 1  is the block diagram of the preferred embodiment of the disk order examining system for a dual-host redundant storage device of this invention; and 
           [0014]      FIG. 2  is the flowchart illustrating steps of the disk order examining method for a dual-host redundant storage device of this invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    Reference will now be made in detail to the present embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts. 
         [0016]    Refer to  FIG. 1 .  FIG. 1  is the block diagram of the preferred embodiment of the disk order examining system for a dual-host redundant storage device of this invention. As shown in  FIG. 1 , the disk order examining system  100  of this invention is applied in a dual-host redundant storage device comprising a master controller  110 , a slave controller  120  and a disk concatenation  130 . The master controller  110  and the slave controller  120  are central controllers with the master-slave relation according to a predetermined regulation of the dual-host redundant storage device. The disk concatenation  130  combines multiple disks,  131 ˜ 130   n,  into a single virtual disk as the JBOD (Just a Bunch of Drives), wherein all the disks  131 ˜ 130   n  link to both the master controller  110  and the slave controller  120 , and respectively provide the master controller  110  and the slave controller  120  for accessing data. The disks  131 ˜ 130   n  in the disk concatenation  130  are linked to the master controller  110  in the sequence of the first configuration  140 . The disks  131 ˜ 130   n  are also linked to the slave controller  120  in the sequence of the second configuration  150 . Moreover, the master controller  110  comprises a data write-in module  111  which generates a plurality of random numbers and sequentially writes the random numbers into the disks  131 ˜ 130   n.  The slave controller  120  comprises an examining module  121  which sequentially reads out the random numbers from the disks  131 ˜ 130   n  and examines whether the first configuration  140  is consistent with the second configuration  150  or not. 
         [0017]    The above-mentioned master controller  110  sequentially writes the random numbers into the disks  131 ˜ 130   n  by data write-in module  111 . Therefore, the random numbers have the sequence of the first configuration  140  and are written into the disks  131 ˜ 130   n  in the sequence of the first configuration  140 . The data write-in module  111  then sends the generated random numbers to the examining module  121  to be the basis of the comparison afterwards. The slave controller  120  then sequentially reads out the random numbers from the disks  131 ˜ 130   n  with the examining module  121 . Therefore, the read out random numbers have the sequence of the second configuration  150 . The examining module  121  in the slave controller  120  can determine whether the second configuration  150  is consistent with the first configuration  140  or not by comparing the random number sequence order in the second configuration  150  with the random number sequence order in the first configuration  140 . If the second configuration  150  is not consistent with the first configuration  140 , that means, the linking order of the disks  131 ˜ 130   n  to the master controller  110  is inconsistent with the linking order of the disks  131 ˜ 130   n  to the slave controller  120 . Therefore, the slave controller  120  should cease the backup function for the master controller  110 . 
         [0018]    Refer to  FIG. 2 .  FIG. 2  is the flowchart illustrating the steps of the disk order examining method for a dual-host redundant storage device of this invention. As shown in  FIG. 2 , first, a master controller  110  generates a plurality of random numbers (Step  200 ). Then the master controller  110  sends the random number sequence order in the first configuration  140  to the slave controller  120  (Step  210 ). Then the master controller  110  sequentially writes the random numbers into the concatenation  130  according to the first configuration  140  (Step  220 ). After the random numbers are written into the concatenation  130 , the slave controller  120  sequentially reads out the random numbers from the disk concatenation  130  in the second configuration  150  order (Step  230 ). Therefore, a random number sequence order having the second configuration  150  is obtained. Then, the examining module  121  determines if the second configuration  150  is consistent with the first configuration  140  (Step  240 ), by comparing the random number sequence order in the second configuration  150  with the random number sequence order in the first configuration  140 . If the second configuration  150  is determined to be inconsistent with the first configuration  140  in Step  240 , that means, the linking order of disks  131 ˜ 130   n  to the master controller  110  is inconsistent with the linking order of the disks  131 ˜ 130   n  to the slave controller  120 . If the dual-host redundant storage device still operates under the condition as the master controller and the slave controller backup for each other, the data accessing will result in errors and cause damage or loss of information. Therefore, the backup function of the slave controller  120  to backup for the master controller  110  must be ceased (Step  250 ). And all the tasks in the dual-host redundant storage device should be temporarily taken over by the master controller  110  until the linking order of disks  131 ˜ 130   n  to the master controller  110  and to the slave controller  120  is rearranged. By this invention, the stability of data accessing in the dual-host redundant storage device is ensured. 
         [0019]    Although the present invention has been described in considerable detail with reference certain embodiments thereof, other embodiments are possible. Therefore, their spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein. 
         [0020]    It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims.