TL-WR703N: Adding Storage Space – EXTROOT

Once you have your TL-WR703N running OpenWrt, you’ll find that it doesn’t have a lot of free space for adding your own files. Here is the output from df from after installing attitude-adjustment:

root@OpenWrt:/# df -h
Filesystem Size Used Available Use% Mounted on
rootfs 1.1M 352.0K 736.0K 32% /
/dev/root 2.0M 2.0M 0 100% /rom
tmpfs 14.3M 56.0K 14.2M 0% /tmp
tmpfs 512.0K 0 512.0K 0% /dev
/dev/mtdblock3 1.1M 352.0K 736.0K 32% /overlay
overlayfs:/overlay 1.1M 352.0K 736.0K 32% /

Note how rootfs has only 736KB free.  Luckily, there’s an easy way to put your rootfs onto external storage (extroot), which lets you easily expand your root file system onto a USB flash drive. In the instructions below, I will illustrate how to implement the pivot overlay flavor of extroot.

First, format your USB flash drive with an ext4 filesystem. I used an old 512MB Crucial USB drive. If you are using Windows, MiniTool Partition Wizard Home Edition can easily create an ext4 filesystem on your USB flash drive.

Before you can mount the USB flash drive on your TL-WR703N, certain packages need to be installed.  ssh into your TL-WR703N, and issue the following commands:

opkg update
opkg install block-mount kmod-fs-ext4 kmod-usb-storage
reboot

After OpenWrt reboots, access it via LuCI in your web browser, and navigate to the System->Mount Points tab. You should see a disabled mount point for /dev/sda1 as below:

mount

Click the Edit button and then check Enable this mount and Use as root filesystem:

extroot

Click Save & Apply, and then reboot OpenWrt.

If you don’t have LuCI installed, you can alternatively directly edit /etc/config/fstab. Add the following lines to the file:

config mount
  option device /dev/sda1
  option fstype ext4
  option is_rootfs 1
  option enabled_fsck 0
  option enabled 1

After your system reboots, if all is well, your USB drive will become your root file system:

root@OpenWrt:/# df -h
Filesystem Size Used Available Use% Mounted on
rootfs 462.3M 2.3M 435.4M 1% /
/dev/root 2.0M 2.0M 0 100% /rom
tmpfs 14.3M 48.0K 14.2M 0% /tmp
tmpfs 512.0K 0 512.0K 0% /dev
/dev/sda1 462.3M 2.3M 435.4M 1% /overlay
overlayfs:/overlay 462.3M 2.3M 435.4M 1% /

Note how rootfs/overlayfs now have 435.4MB free. From LuCI, it looks like this:

overlay

 

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