Patent ID: 7225294

Claim:
A control method for a storage system which comprises a plurality of information processing units, a managing computer, a storage device provided with a plurality of logical volumes, and a user interface, said control method comprising: performing a first process in which when a data write request to a first logical volume is sent from the information processing unit to the storage device the storage device stores data in the first logical volume and also stores the data in a second logical volume; performing a second process in which the storage device suspends the first process; shifting from the second process to the first process to perform the first process; when shifting from the second process to the first process to perform the first process, inquiring an information processing unit which can access the second logical volume, of whether said information processing unit mounts the second logical volume or not; deciding whether said information processing unit mounts the second logical volume or not; when the information processing unit mounts the second logical volume, outputting that effect from said user interface before shifting to the first process; accepting a change of pair condition between said first logical volume and said second logical volume at the managing computer, wherein said accepted change comprises a shift from said second process to said first process initiated through the user interface, wherein said managing computer inquires to an information processing unit accessible to said second logical volume as to whether or not said second logical volume is mounted available to read and write from said information processing unit; when as a result of said inquiring by the managing computer, if the managing computer finds that said second logical volume is mounted available to read and write from said information processing unit, then outputting an indication that the second logical volume is mounted through the user interface of the managing computer without instructing the change to said pair condition to said information processing unit.