Hi, The mkfs.jffs2 has some options, in which -e option specifies the erase block size, which by default is 64KiB. While making a jffs2 image of a directory (which has some files) of size 3848192 Bytes. ./mkfs.jffs2 -d directory -o jffs2_img -e 128KiB With default option for erase block size ( 64KiB), the jffs2 image size was : 1983612 Bytes. ( 1.89 MB) With -e 128KiB , the jffs2 image size was : 7687900 Bytes (7.33 MB) With -e 256KiB , the jffs2 image size was : 4289164 Bytes (4.09 MB) Why is that the jffs2 image size is varying with the erase block size.? If i have an erase size of 256KiB(on flash), is it necessary that i should build a jffs2 image with the -e 256KiB option. regards ashok