Methods for operating a non-volatile storage system are described. The non-volatile storage system includes a plurality of bit lines, a plurality of word line combs each comprising a plurality of word lines, and a plurality of resistance-switching memory elements. Each resistance-switching memory element is coupled between one of the bit lines and one of the word lines. The method includes calibrating a plurality of bias voltages for the word lines and bit lines based on estimates of data values stored in the resistance-switching memory elements.