Storage system and snapshot data preparation method in storage system

A storage system comprising:

• a physical snapshot execution part which writes data that has been updated into both a primary storage device and a secondary storage device;
• a logical snapshot execution part which writes input data into a primary storage device, and which writes differential data between said data and data prior to updating into a secondary storage device;
• an update data search part which performs a search in order to ascertain whether or not data that is to be updated is present in the primary storage device involved in a snapshot data preparation request when such a preparation request is received from a higher-level device;
• an access degree-of-competition judgment part which, when said update data search part finds update data in said primary storage device, and said primary storage device and said secondary storage device are simultaneously accessed from said higher-level device, judges whether or not the degree of competition between the access to said primary storage device and the access to said secondary storage device is high;
• and
• a snapshot execution part selection part which selectively drives said physical snapshot execution part when said access degree-of-competition judgment part judges that said access degree of competition is high, and which selectively drives said logical snapshot execution part when said access degree-of-competition judgment part judges that said access degree of competition is not high.

A storage system comprising:

• a physical snapshot execution part which writes data that has been updated into both a primary storage device and a secondary storage device;
• a logical snapshot execution part which writes input data into a primary storage device, and which writes differential data between said data and data prior to updating into a secondary storage device;
• an update data search part which performs a search in order to ascertain whether or not data that is to be updated is present in the primary storage device involved in a snapshot data preparation request when such a preparation request is received from a higher-level device;
• a trouble degree-of-occurrence judgment part which judges whether or not the degree of occurrence of trouble in said primary storage device is high when said update data search part finds update data in said primary storage device;
• and
• a snapshot execution part selection part which selectively drives said physical snapshot execution part when said trouble degree-of-occurrence judgment part judges that the degree of occurrence of trouble in said primary storage device is high, and which selectively drives said logical snapshot execution part when said trouble degree-of-occurrence judgment part judges that the degree of occurrence of said trouble is not high.

A storage system comprising:

• a physical snapshot execution part which writes data that has been updated into both a primary storage device and a secondary storage device;
• a logical snapshot execution part which writes input data into a primary storage device, and which writes differential data between said data and data prior to updating into a secondary storage device;
• an empty region monitoring part which monitors the empty region of a data storage region that is provided in order to save the data stored in the primary storage device involved in a snapshot data preparation request when there is such a data preparation request from a higher-level device;
• and
• a snapshot execution part selection part which selectively drives said physical snapshot execution part when said empty region monitoring part judges that the empty region in said data storage region is small, and which selectively drives said logical snapshot execution part when said empty region monitoring part judges that said empty region is not small.

A method for preparing snapshot data in a storage system, comprising:

• a first step of executing a physical snapshot that writes data that has been updated into both a primary storage device and a secondary storage device;
• a second step of executing a logical snapshot that writes input data into the primary storage device, and that writes differential data between this data and data prior to updating into the secondary storage device;
• a third step of conducting a search in order to ascertain whether or not data that is to be updated is present in the primary storage device involved in a snapshot data preparation request when such a preparation request is received from a higher-level device;
• a fourth step of judging whether or not the amount of data updated in said primary storage device is greater than a specified, when update data is found in said primary storage device in said third step;
• and
• a fifth step in which, when it is judged that said amount of updated data is greater than said specified value, the execution of said physical snapshot is selected, while when it is judged that said amount of updated data is smaller than said specified value, or when update data is not found in said storage device, the execution of said logical snapshot is selected.