When i do the following.
"cat /proc/mounts".
tmpfs /export/ftp/import tmpfs rw,relatime,size=102400k 0 0
tmpfs /export/ftp/export tmpfs rw,relatime,size=10240k,mode=755 0 0
The documentation of embedded device said that import and export are located in DRAM
However in other equipment
ubi18_0 /nvdata1/temporary-download ubifs rw,sync 0 0
ubi18_0 /export/ftp/import ubifs rw,sync 0 0
ubi18_0 /export/http/import ubifs rw,sync 0 0
tmpfs /export/ftp/export tmpfs rw,size=10240k,mode=755 0 0
The documentation of embedded device said that import is located in NAND and export are located in DRAM.
I really do not know what resides in DRAM, NAND, NOR.
The basic knowledge i have in our equiment is that NOR has u-boot. NAND has kernel and rootfs.
Format of /proc/mounts
The 1st column specifies the device that is mounted.
The 2nd column reveals the mount point.
The 3rd column tells the file-system type.
The 4th column tells you if it is mounted read-only (ro) or read-write (rw).
The 5th and 6th columns are dummy values designed to match the format used in /etc/mtab.
tmpfs /export/ftp/import tmpfs rw,relatime,size=102400k 0 0
tmpfs /export/ftp/export tmpfs rw,relatime,size=10240k,mode=755 0 0
Meaning : Two independent tmpfs-es are mounted at both /export/ftp/import and /export/ftp/export. Any data stored into these directories is lost upon rebooting the kernel. tmpfs is essentially a ramdisk-like construct that stores data in the RAM. Technically speaking tmpfs is mapped into virtual memory which uses RAM and swap (if present).
ubi18_0 /nvdata1/temporary-download ubifs rw,sync 0 0
ubi18_0 /export/ftp/import ubifs rw,sync 0 0
ubi18_0 /export/http/import ubifs rw,sync 0 0
tmpfs /export/ftp/export tmpfs rw,size=10240k,mode=755 0 0
Meaning : The same "partition" on the NAND device (ubi18_0) is mounted at 3 different mount-points. ubi is a intermediate file-system layer that simplifies and optimises I/O with the underlying flash media devices. Also a temporary filesystem is mounted at /export/ftp/export.
来源：https://stackoverflow.com/questions/18122123/how-to-interpret-proc-mounts