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:
 a computer;   a first storage system coupled to the computer and including a first cache memory and a first disk drive;   a second storage system coupled to the computer and the first storage system and including a second cache memory and a second disk drive; and   a third storage system coupled to the first storage system and the second storage system and including a third disk drive to provide a third logical volume based on the third disk drive,   wherein the first storage system provides a first logical volume based on the first disk drive, and a fourth logical volume based on the third logical volume based on a volume and storage conversion table in the first storage system,   wherein the second storage system provides a second logical volume based on the second disk drive, and a fifth logical volume based on the third logical volume based on a volume and storage conversion table in the second storage system,   wherein the first storage system and the second storage system store copy pair management information indicating a pair between the first logical volume and the second logical volume and a pair between the fourth logical volume and the fifth logical volume,   wherein the first cache memory and the second cache memory store first write data designated to the first logical volume and second write data designated to the fourth logical volume, from the computer, by transmitting the first write data and the second write data from the first storage system to the second storage system according to the copy pair management information,   wherein the first storage system destages the first write data from the first cache memory to the first disk drive,   wherein the second storage system destages the first write data from the second cache memory to the second disk, and   wherein a certain storage system which is one of the first storage system and the second storage system destages the second write data from a cache memory in the certain storage system to the third logical volume according to a volume and storage conversion table in the certain storage system.   
   
   
       2 . A computer system according to  claim 1 ,
 wherein an other storage system, which is an other one of the first storage system and the second storage system, deletes the second write data from a cache memory in the other storage system without destaging the second write data from the cache memory in the other storage system.   
   
   
       3 . A computer system according to  claim 2 ,
 wherein an initial copy between the first logical volume and the second logical volume is performed while an initial copy between the fourth logical volume and the fifth logical volume is not performed.   
   
   
       4 . A computer system according to  claim 3 ,
 wherein the transmission of the first write data and the second write data from the first storage system to the second storage system is executed as a bi-directional synchronous copy.   
   
   
       5 . A data storing system receiving writing requests from a computer, comprising:
 a first storage system coupled to the computer and including a first cache memory and a first disk drive;   a second storage system coupled to the computer and the first storage system and including a second cache memory and a second disk drive; and   a third storage system coupled to the first storage system and the second storage system and including a third disk drive to provide a third logical volume based on the third disk drive;   wherein the first storage system provides a first logical volume based on the first disk drive, and a fourth logical volume based on the third logical volume based on a volume and storage conversion table in the first storage system,   wherein the second storage system provides a second logical volume based on the second disk drive, and a fifth logical volume based on the third logical volume based on a volume and storage conversion table in the second storage system,   wherein the first storage system and the second storage system store copy pair management information indicating a pair between the first logical volume and the second logical volume and a pair between the fourth logical volume and the fifth logical volume,   wherein the first cache memory and the second cache memory store first write data designated to the first logical volume and second write data designated to the fourth logical volume associated with the writing requests, by transmitting the first write data and the second write data from the first storage system to the second storage system according to the copy pair management information,   wherein the first storage system destages the first write data from the first cache memory to the first disk drive,   wherein the second storage system destages the first write data from the second cache memory to the second disk, and   wherein a certain storage system which is one of the first storage system and the second storage system destages the second write data from a cache memory in the certain storage system to the third logical volume according to a volume and storage conversion table in the certain storage system.   
   
   
       6 . A data storing system according to  claim 5 ,
 wherein an other storage system, which is an other one of the first storage system and the second storage system, deletes the second write data from a cache memory in the other storage system without destaging the second write data from the cache memory in the other storage system.   
   
   
       7 . A data storing system according to  claim 6 ,
 wherein an initial copy between the first logical volume and the second logical volume is performed while an initial copy between the fourth logical volume and the fifth logical volume is not performed.   
   
   
       8 . A data storing system according to  claim 7 ,
 wherein the transmission of the first write data and the second write data from the first storage system to the second storage system is executed as a bi-directional synchronous copy.   
   
   
       9 . A data storing method for a computer system including a computer, a first storage system including a first cache memory and a first disk drive, a second storage system including a second cache memory and a second disk drive, and a third storage system including a third disk drive, comprising:
 by the third storage system, providing a third logical volume based on the third disk drive to the first storage system and the second storage system;   by the first storage system, providing a first logical volume based on the first disk drive, and a fourth logical volume based on the third logical volume based on a volume and storage conversion table in the first storage system;   by the second storage system, providing a second logical volume based on the second disk drive, and a fifth logical volume based on the third logical volume based on a volume and storage conversion table in the second storage system;   by the first storage system and the second storage system, storing copy pair management information indicating a pair between the first logical volume and the second logical volume and a pair between the fourth logical volume and the fifth logical volume;   by the first storage system, storing first write data designated to the first logical volume and second write data designated to the fourth logical volume associated with the writing requests, to the first cache memory;   by the first storage system, transmitting the first write data and the second write data to the second storage system according to the copy pair management information;   by the second storage system, storing the first write data and the second write data, each transmitted, to the second cache memory;   by the first storage system, destaging the first write data from the first cache memory to the first disk drive;   by the second storage system, destaging the first write data from the second cache memory to the second disk; and   by a certain storage system which is one of the first storage system and the second storage system, destaging the second write data from a cache memory in the certain storage system to the third logical volume according to a volume and storage conversion table in the certain storage system.   
   
   
       10 . A data storing method according to  claim 9 , comprising:
 by an other storage system, which is an other one of the first storage system and the second storage system, deleting the second write data from a cache memory in the other storage system without destaging the second write data from the cache memory in the other storage system.   
   
   
       11 . A data storing method according to  claim 10 ,
 wherein an initial copy between the first logical volume and the second logical volume is performed while an initial copy between the fourth logical volume and the fifth logical volume is not performed.   
   
   
       12 . A data storing method according to  claim 11 ,
 wherein the transmission of the first write data and the second write data from the first storage system to the second storage system is executed as a bi-directional synchronous copy.