Storage system, data restoring method, and data access method

A storage system comprising a disk drive for storing data and a control unit connected to the disk drive, for controlling data read/write from/to volumes set in the disk drive

• wherein the volumes include a first volume and a second volume, the first volume storing data that can be copied to the second volume, and
• wherein, after the copying is finished, the control unit
• consults, in a case where a request to read data from the first volume is received, a first meta data associate with data stored in a first block of the first volume designated by the read request,
• reads, in a case where information indicating of a failure is set to the consulted first meta data, a second data from a second block, which is associated with the first block of the first volume, and is located in the second volume, and
• reads, in a case where information indicating a failure is not set to the consulted first meta data, a first data from the first block of the first volume designated by the read request.

A volume restoring method for restoring data of a volume in a storage system, the storage system comprising a disk drive for storing data and a control unit connected to the disk drive, for controlling data read/write from/to volumes set in the disk drive,

• wherein the volumes include a first volume and a second volume, the first volume storing data that can be copied to the second volume,
• the volume restoring method comprising the following steps, which are executed after the copying is finished:
• a first step of consulting a first meta data associated with data stored in a first block of the first volume;
• a second step of judging whether or not the consulted first meta data includes information indicating that the data stored in the first block of the first volume is prohibited from being updated for a given period;
• a third step of consulting, in a case where the consulted first meta data includes information indicating that the data stored in the first block of the first volume is prohibited from being updated for a given period, a meta data for a block that allows the first block of the first volume;
• a fourth step of restoring, in a case where the consulted first meta data does not include information indicating that the data stored in the first block of the first volume is prohibited from being updated for a given period, data stored in the second volume into the first volume by copying data stored in the second block, which is associated with the first block of the first volume, and is located in the second volume, to the first block of the first volume;
• and
• a fifth step of comparing data stored in the first block of the first volume with data stored in the second block of the second volume;
• and
• a sixth step of setting, when the data stored in the first block of the first volume does not coincide with the data stored in the second block of the second volume, information indicating of a failure to the first meta data.

A volume restoring method for restoring data of a volume in a storage system, the storage system comprising a disk drive for storing data and a control unit connected to the disk drive, for controlling data read/write from/to volumes set in the disk drive,

• wherein the volumes includes a first volume and a second volume, the first volume storing data that can be copies to the second volume, and
• the data access method comprising the following steps, which are executed after the copying is finished:
• a seventh step of consulting, in a case where a request to read data from the first volume is received, a first meta data associated with data stored in a first block of the first volume designated by the read request;
• an eight step of reading, in a case where information indicating of a failure is set to the consulted first meta data, a second data from a second block, which is associated with the first block of the first volume, and is located in the second volume;
• and
• a ninth step of reading, in a case where information indicating of a failure is not set to the consulted first meta data, a first data from the first block of the first volume designated by the read request.