A storage system allocates a data storage area in response to an access request from a first computer if the capacity of a first physical storage device configuring a first logical storage area, provided to the first computer, is equal to or lower than a predetermined threshold. The storage system associates the first logical storage area with another physical storage device, which is different from the first physical storage device associated with a second logical storage area provided to the first computer and a second computer, and allocates a data storage area from the another physical storage device if the capacity of the first physical storage device associated with the first logical storage area exceeds the predetermined threshold.