from all the pages the parity value is calculated and written in a parity page designated for the block with a column parity calculated for the same sector in all the pages of the block group parity in the second dimensional raid provides additional parity protection in a flash memory device a group parity for a parity group that includes less than all pages of a block sets a higher level of protection than column parity which is illustrated in fig6 as a first step the number of pages in the parity group is selected as the group size this number is chosen carefully in order to provide adequate protection from paired page faults and is often selected by the mlc flash memory manufacturer for the pairing chosen a typical group size is 8 fig8 shows group parity with 8 pages in each parity sector group in fig8 pages p 3 p 11 p 59 are parity pages fig1 illustrates a parity grouping configuration applicable to the configuration shown in fig8 according to one embodiment of the present invention as shown in fig1 the first group i e group 1 is a half group in each subsequent group of 8 pages the first 4 pages are paired with the 4 pages in the previous group for instance if the page pairing sequence at the multiple level cells is 0 4 1 5 2 6 and 3 7 i e page 0 is paired to page 4 page 1 is paired to page 5 page 2 is paired to page 6 and page 3 is paired to page 7 then for each write of any of pages 0 1 2 a.