When using a router flashed with OpenWRT, you may find that the capacity of the filesystem is much smaller than the real capacity. For example, the router I use is Netgear WNDR4300 which has a 128MB Nand flash. But when using the 'df -h' command to inspect the space usage status, I surprisingly found that the space of the total mounting point '/' is only 14MB. So to find out the reason and try to expand usable space, I used the command "dmesg" and "cat /proc/mtd" to collect the information of mtd devices. [ 0.634792] nand: device found, Manufacturer ID: 0x2c, Chip ID: 0xf1 [ 0.641287] nand: Micron NAND 128MiB 3,3V 8-bit [ 0.645888] nand: 128 MiB, SLC, erase size: 128 KiB, page size: 2048, OOB size: 64 [ 0.653625] Scanning device for bad blocks [ 0.661590] random: fast init done [ 0.744785] 12 cmdlinepart partitions found on MTD device ar934x-nfc [ 0.751249] Creating 12 MT...