1. A method for setting a mode of a storage device including a plurality of memory chips, the method comprising: determining whether a number of bad blocks of a first memory chip among the plurality of memory chips is higher than a threshold value; setting the first memory chip to a read only mode if the number of the bad blocks is higher than the threshold value; and storing metadata of the first memory chip set to the read only mode to a second memory chip among the plurality of memory chips if the number of the bad blocks is higher than the threshold value.