Data storing system and operating method thereof

A method of operating a data storing system, comprising:

• performing a read operation using a first read voltage listed on a read retry table;
• storing read data at a first position of a buffer when the read operation fails;
• performing a read operation using a second read voltage adjacent to the first read voltage in a first direction on the read retry table;
• storing read data at a second position of the buffer when the read operation fails;
• performing a read operation using a third read voltage adjacent to the second read voltage in the first direction on the read retry table;
• storing read data at a third position of the buffer when the read operation fails;
• changing a direction on the read retry table to determine a read voltage to be used for the read operation among read voltages listed on the read retry table based on the data stored at the first to third positions of the buffer;
• performing the read operation using the determined read voltage;
• and
• storing the determined read voltage which is used when the read operation passes and the direction during the read operation when the read operation passes.