Patent ID: 8438350

Claim:
A storage apparatus comprising: a first to an Mth (M is an integer of two or more) copy source disk groups, each of the copy source disk groups including one or more copy source physical disks; a first to an Mth copy destination disk groups respectively corresponding to the first to the Mth copy source disk groups, each of the copy destination disk groups including one or more copy destination physical disks; and a copy control unit to manage a copy session for copying a copy source data area in at least one of the first to the Mth copy source disk groups to a copy destination data area in a corresponding copy destination disk group, to set a first to an Mth copy session groups, each of the copy session groups including one or more copy sessions from the ith (i=1, 2, . . . , M) copy source disk group to the ith copy destination disk group as the copy session, and to perform repeatedly a selection operation to cyclically select a copy session from each of the first to the Mth copy session groups in a predetermined sequence and a control operation to cyclically execute copy processing on a predetermined copy processing unit basis for the M copy sessions selected by the selection operation in a predetermined sequence for a prescribed number of times, wherein the copy control unit includes: a monitoring unit to monitor a write response time of the copy destination disk group in the copy processing by the control operation for each copy session, and a changing unit to dynamically change the prescribed number of times of each copy session depending on the write response time monitored by the monitoring unit.