Abstract: The usage amount of a pool area is avoided from becoming equal to 100%, thereby preventing all snapshot images from being crashed. There is provided a disk-array apparatus including a control processor. Here, the control processor controls a data reading/writing from/into a first logical volume created using a memory area of plural disk drives, and controls past data such that the past data is written into a second logical volume as differential data on each generation basis, the past data being stored into the first logical volume, and manages the differential data. If the amount of the differential data stored into the second logical volume has exceeded a first predetermined value, the control processor determines a generation of the differential data to be deleted from among the differential data written into the second logical volume. The control processor deletes the differential data of the generation determined.

Abstract: A highly advantageous storage system and a snapshot management method. In the storage system, write target data sent from a host computer to a first storage controller is duplicated and stored in the first storage controller and also in a second storage controller; when the first storage controller receives a request from the host computer to create a snapshot in the second storage controller, it suspends transferring differential data to the second storage controller, creates a new first snapshot, and transfers differential data for the created first snapshot together with the untransferred differential data for a previous first snapshot for which transferring had been suspended, to the second storage controller.

Abstract: A highly advantageous storage system and a snapshot management method. In the storage system, write target data sent from a host computer to a first storage controller is duplicated and stored in the first storage controller and also in a second storage controller; when the first storage controller receives a request from the host computer to create a snapshot in the second storage controller, it suspends transferring differential data to the second storage controller, creates a new first snapshot, and transfers differential data for the created first snapshot together with the untransferred differential data for a previous first snapshot for which transferring had been suspended, to the second storage controller.

Abstract: The usage amount of a pool area is avoided from becoming equal to 100%, thereby preventing all snapshot images from being crashed. There is provided a disk-array apparatus including a control processor. Here, the control processor controls a data reading/writing from/into a first logical volume created using a memory area of plural disk drives, and controls past data such that the past data is written into a second logical volume as differential data on each generation basis, the past data being stored into the first logical volume, and manages the differential data. If the amount of the differential data stored into the second logical volume has exceeded a first predetermined value, the control processor determines a generation of the differential data to be deleted from among the differential data written into the second logical volume. The control processor deletes the differential data of the generation determined.

Abstract: The usage amount of a pool area is avoided from becoming equal to 100%, thereby preventing all snapshot images from being crashed. There is provided a disk-array apparatus including a control processor. Here, the control processor controls a data reading/writing from/into a first logical volume created using a memory area of plural disk drives, and controls past data such that the past data is written into a second logical volume as differential data on each generation basis, the past data being stored into the first logical volume, and manages the differential data. If the amount of the differential data stored into the second logical volume has exceeded a first predetermined value, the control processor determines a generation of the differential data to be deleted from among the differential data written into the second logical volume. The control processor deletes the differential data of the generation determined.

Abstract: The usage amount of a pool area is avoided from becoming equal to 100%, thereby preventing all snapshot images from being crashed. There is provided a disk-array apparatus including a control processor. Here, the control processor controls a data reading/writing from/into a first logical volume created using a memory area of plural disk drives, and controls past data such that the past data is written into a second logical volume as differential data on each generation basis, the past data being stored into the first logical volume, and manages the differential data. If the amount of the differential data stored into the second logical volume has exceeded a first predetermined value, the control processor determines a generation of the differential data to be deleted from among the differential data written into the second logical volume. The control processor deletes the differential data of the generation determined.