Dual writing device and its control method

Abstract

A first storage system sets a storage area of a first disk drive as a first volume, and misrepresents an identifier of the storage system and an identifier of the first volume. A second storage system sets a storage area of a second disk drive as a second volume, and misrepresents an identifier of the storage system and an identifier of the second volume. The first storage system copies data of the first volume in the second volume. The second storage system copies data of the second volume in the first volume. A management computer determines whether there is a match between the data of the first volume and the data of the second volume. When it is determined that there is not match, the host computer accesses only one of the first volume and the second volume that stores the latest data.

1 . A computer system, comprising:
 one or more first storage systems;   one or more second storage systems;   one or more host computers connected to the first storage system and to the second storage system through a network; and   a management computer capable of accessing the first storage system, the second storage system, and the host computers, wherein:   the first storage system includes:
 a first interface connected to the network; 
 a first processor connected to the first interface, 
 a first memory connected to the first processor; and 
 a first disk drive for storing data requested to be written by the host computer; 
   the first storage system sets a storage area of the first disk drive as one or more first volume;   the first storage system misrepresents an identifier of the storage system and an identifier of the first volume to the host computer;   the first storage system provides the set first volume to the host computer,   the second storage system includes:
 a second interface connected to the network; 
 a second processor connected to the second interface; 
 a second memory connected to the second processor; and 
 a second disk drive for storing data requested to be written by the host computer; 
   the second storage system sets a storage area of the second disk drive as one or more second volume;   the second storage system misrepresents an identifier of the storage system and an identifier of the second volume as being identical to those misrepresented by the first storage system to the host computer;   the second storage system provides the set second volume to the host computer;   the management computer includes:
 a third interface externally connected; 
 a third processor connected to the third interface; and 
 a third memory connected to the third processor; 
   the host computer includes:
 a fourth interface connected to the network; 
 a fourth processor connected to the fourth interface; and 
 a fourth memory connected to the fourth processor; 
   the first processor copies data of the first volume in the second volume;   the second processor copies data of the second volume in the first volume;   the third processor determines whether there is a match between the data of the first volume and the data of the second volume; and   if it is determined that there is no match, the fourth processor accesses only one of the first volume and the second volume that stores the latest data.   
   
   
       2 . The computer system according to  claim 1 , wherein:
 the third processor specifies one of the first volume and the second volume that is a copying destination in the copying process of the first processor or the second processor;   the third processor gives the fourth processor an instruction for suspending access to the specified volume of the copying destination; and   the fourth processor, upon reception of the instruction for suspending access, suspends the access to the volume of the copying destination to thereby access only one of the first volume and the second volume that stores the latest data.   
   
   
       3 . The computer system according to  claim 1 , wherein the fourth processor suspends access to one of the first volume and the second volume when instructed to suspend copying process of the first processor or the second processor. 
   
   
       4 . The computer system according to  claim 1 , wherein upon detecting a failure occurring in the copying process of the volume, the first processor gives the fourth processor an instruction for suspending access to one of the first volume and the second volume. 
   
   
       5 . An access control method for a computer system, the computer system including: one or more first storage systems; one or more second storage systems; one or more host computers connected to the first storage systems and to the second storage systems through a network; and a management computer capable of accessing the first storage systems, the second storage systems, and the host computers,
   the first storage system including: a first interface connected to the network; a first processor connected to the first interface; a first memory connected to the first processor; and a first disk drive for storing data requested to be written by the host computer,   the second storage system including: a second interface connected to the network; a second processor connected to the second interface; a second memory connected to the second processor; and a second disk drive for storing data requested to be written by the host computer,   the management computer including: a third interface externally connected; a third processor connected to the third interface; and a third memory connected to the third processor,   the host computer including: a fourth interface connected to the network; a fourth processor connected to the fourth interface; and a fourth memory connected to the fourth processor,     the access control method comprising the steps of:   setting a storage area of the first disk drive as one or more first volumes;   misrepresenting an identifier of the storage system and an identifier of the first volume to the host computer;   providing the set first volume to the host computer;   setting a storage area of the second disk drive as one or more second volumes;   misrepresenting an identifier of the storage system and an identifier of the second volume as being identical to those misrepresented by the first storage system to the host computer;   providing the set second volume to the host computer;   copying data of the first volume in the second volume;   copying data of the second volume in the first volume;   determining whether there is a match between the data of the first volume and the data of the second volume; and   accessing only one of the first volume and the second volume that stores the latest data when it is determined there is no match.   
   
   
       6 . The access control method according to  claim 5 , further comprising the step of specifying one of the first volume and the second volume that is a copying destination in the copying step,
 wherein the step of accessing only one of the volumes that stores the latest data comprises suspending access to the specified volume of the copying destination.   
   
   
       7 . The access control method according to  claim 5 , further comprising the step of suspending access to one of the first volume and the second volume, upon reception of an instruction for suspending the process of the copying step. 
   
   
       8 . The access control method according to  claim 5 , further comprising the step of instructing to suspend access to one of the first volume and the second volume, upon detection of a failure occurring in the process of the copying step. 
   
   
       9 . A management computer, comprising:
 an interface capable of accessing one or more first storage systems, one or more second storage systems, and one or more host computers connected to the first and second storage systems through a network;   a processor connected to the interface; and   a memory connected to the processor, wherein:   the first storage system includes a first disk drive for storing data requested to be written by the host computer;   the first storage system sets a storage area of the first disk drive as one or more first volume;   the first storage system misrepresents an identifier of the storage system and an identifier of the first volume to the host computer;   the first storage system provides the set first volume to the host computer;   the second storage system includes a second disk drive for storing data requested to be written by the host computer;   the second storage system sets a storage area of the second disk drive as one or more second volume;   the second storage system misrepresents an identifier of the storage system and an identifier of the second volume as being identical to those misrepresented by the first storage system to the host computer;   the second storage system provides the set second volume to the host computer;   the first storage system copies data of the first volume in the second volume;   the second storage system copies data of the second volume in the first volume;   the processor determines whether there is a match between the data of the first volume and the data of the second volume; and   the processor gives the host computer an instruction for accessing only one of the first volume and second volume that stores the latest data when it is determined that there is no match.   
   
   
       10 . The management computer according to  claim 9 , wherein:
 the processor specifies which one of the first volume and second volume is a copying destination in the copying process of one of the first processor and the second processor; and   the processor gives the host computer an instruction for suspending access to the specified volume of the copying destination to thereby instruct the host computer to access only one of the volumes that stores the latest data.   
   
   
       11 . A computer system, comprising:
 one or more storage systems;   one or more first misrepresentation devices connected to the storage system;   one or more second misrepresentation devices connected to the storage system;   one or more host computers connected to the first misrepresentation device and the second misrepresentation device through a network; and   a management computer capable of accessing the first misrepresentation device, the second misrepresentation device, and the host computers, wherein:   the storage system includes:
 a first interface connected to the first misrepresentation device and the second misrepresentation device; 
 a first processor connected to the first interface; 
 a first memory connected to the first processor; and 
 a first disk drive for storing data requested to be written by the host computer; 
   the storage system provides a storage area of the first disk drive as one or more first volume to the first misrepresentation device and the second misrepresentation device;   the first misrepresentation device includes:
 a second interface connected to the network; 
 a second processor connected to the second interface; 
 a second memory connected to the second processor; and 
 a first cache memory for temporarily storing data stored in the provided first volume; 
   the first misrepresentation device misrepresents an identifier of the storage system and an identifier of the provided first volume;   the first misrepresentation device provides the provided first volume to the host computer;   the second misrepresentation device includes:
 a third interface externally connected; 
 a third processor connected to the third interface; 
 a third memory connected to the third processor; and 
 a second cache memory for temporarily storing data stored in the provided first volume; 
   the second misrepresentation device misrepresents an identifier of the storage system and an identifier of the provided first volume;   the second misrepresentation device provides the provided first volume to the host computer;   the management computer includes:
 a fourth interface externally connected; 
 a fourth processor connected to the fourth interface; and 
 a fourth memory connected to the fourth processor; 
   the host computer includes:
 a fifth interface connected to the network; 
 a fifth processor connected to the fifth interface; and 
 a fifth memory connected to the fifth processor; 
   the second processor copies data of the first cache memory in the second cache memory;   the third processor copies data of the second cache memory in the first cache memory;   the fourth processor determines whether there is a match between the data of the first cache memory and the data of the second cache memory; and   when it is determined that there is no match, the fifth processor accesses only one of the first cache memory and the second cache memory that stores the latest data.   
   
   
       12 . The computer system according to  claim 11 , wherein:
 the fourth processor specifies which one of the first cache memory and the second cache memory is a copying destination in the copying process of one of the second processor and the third processor; and   the fourth processor gives the fifth processor an instruction for suspending access to the specified cache memory of the copying destination; and   the fifth processor, upon reception of the instruction for suspending access, suspends access to the cache memory of the copying destination to thereby access only one of the first cache memory and the second cache memory that stores the latest data.   
   
   
       13 . The computer system according to  claim 1   1 , wherein when instructed to suspend the copying process of the second processor or the third processor, the fifth processor suspends access to one of the first cache memory and the second cache memory. 
   
   
       14 . The computer system according to  claim 11 , wherein upon detection of a failure occurring in the copying process of the volume, the second processor gives the fifth processor an instruction for suspending accessing to one of the first cache memory and second cache memory.