The backup dir has the separated files:
root@TL_WR941HP:/# cat /proc/mtd
dev: size erasesize name
mtd0: 00010000 00010000 "u-boot"
mtd1: 006c0000 00010000 "rootfs"
mtd2: 00030000 00010000 "rootfs_data"
mtd3: 00110000 00010000 "kernel"
mtd4: 00010000 00010000 "mib0"
mtd5: 00010000 00010000 "art"
mtd6: 007d0000 00010000 "firmware"
root@TL_WR941HP:/# cat /proc/partitions
major minor #blocks name
31 0 64 mtdblock0
31 1 6912 mtdblock1
31 2 192 mtdblock2
31 3 1088 mtdblock3
31 4 64 mtdblock4
31 5 64 mtdblock5
31 6 8000 mtdblock6
There is also a one file complete backup called full_backup.bin