System using copy of current pointer saved before changing a selectively restoring original data based upon status of updating flag

An updating method for data groups stored in a data processing system comprising a nonvolatile storage device including a data storage portion comprising pairs of first and second data domains, an information management table including contents and for managing a current pointer, and a pointer updating log management table, said method comprising the steps of:

• (a) setting a data updating sequence flag used for indicating completion of data updating;
• (b) storing contents of the current pointer managed by the information management table in the pointer updating log management table;
• (c) transferring contents of a first data domain, which are an object to be updated and are designated by the current pointer, to a second data domain when data updating is carried out;
• (d) changing the contents of the information management table from the current pointer to a new current pointer pointing to the second data domain in response to said step (b);
• (e) restoring when an interruption occurs during at least one of said steps (c) and (d), the contents of the pointer updating log management table current pointer into the information management table;
• and
• (f) resetting the data updating sequence flag after one of said steps (d) and (e).

A system for executing an updating method for data groups stored in a nonvolatile storage device, comprising:

• data storage means for storing data and comprising a first data domain and a second data domain which constitute a pair;
• information management table means for managing a first pointer pointing to the first data domain, a second pointer pointing to the second data domain, and a current pointer pointing to one of the first and second data domains which stores currently valid data;
• pointer updating log management table means for temporarily storing the current pointer before one of the pair of data domains is updated;
• a data updating processor for updating data using the first, second and current pointers by first temporarily storing the current pointer in said pointer updating log management table means, by second updating one of the first and second data domains and by third changing the current pointer in said information management table means to a new current pointer pointing to the updated data domain after the updating of data;
• and
• a data restoring processor for restoring information in the one of the first and second data domains by setting contents of said information management table means to the current pointer stored in said pointer updating log management table means when said data updating processor is interrupted.
• wherein said nonvolatile storage device further comprises a data updating sequence flag used for indicating completion of data updating;
• wherein said data updating processor sets said data updating sequence flag when said data updating processor begins the updating and resets said data updating sequence flag when said data updating processor ends the updating;
• and
• wherein said data restoring processor resets said data updating sequence flag when said restoring processor ends the restoring.