Patent ID: 8832396

Claim:
A storage apparatus comprising: one or more storage devices for providing a storage area; and a controller for creating first and second logical volumes in the storage area provided by the one or more storage devices and reading data from and/or writing data to the first logical volume in response to a request from a host computer, the controller being equipped with a memory, wherein the controller: obtains one or more snapshots, each of which are data images of the first logical volume at a certain point in time, and stores management information of each obtained snapshot in the second logical volume; and reads the management information of a necessary snapshot of the one or more snapshots from the second logical volume to the memory when needed, executes processing using the read management information, and returns the management information, which becomes no longer necessary, from the memory to the second logical volume, and when reading the management information of the necessary snapshot from the second logical volume to the memory, the controller changes the number of generations in a generation block and address range of the management information of the necessary snapshot to be read to the memory whose management information is required according to a number of generations of snapshots existing at the time of the reading.