Many useful OpenWrt utilities and packages rely on external storage to hold data files. This guide describes how to add a single USB stick or drive to your OpenWrt device.

Note: If you have a memory limited router (say with 4MBytes Flash internal storage), and want to be able to install more packages, you should instead read the Extroot Configuration page.

Requirements:

• Your device/router itself must have at least 8 MB Flash. Lower capacity devices will not be able to hold the required packages.
• The USB drive you're adding can be of any capacity.
• This procedure WILL ERASE THE USB DRIVE. Copy any data you care about to another destination.
• This quickstart requires you to ssh into the router.

Procedure:

1. Use your laptop/desktop computer to format your USB device. Use the default name and format options. This prepares the USB drive for the process below, which will erase those settings (again). Warning: This initial formatting will erase the entire USB drive.

2. SSH into the router and enter the following commands into the SSH window.

3. Update and download required packages: More... You may see error messages about installing kmod-usb3 on certain routers. These can be ignored since the hardware may not support USB3.

opkg update && opkg install block-mount e2fsprogs kmod-fs-ext4 kmod-usb-storage kmod-usb2 kmod-usb3

4. Enter ls -al /dev/sd* to show the name of all attached USB devices. The list may be empty if there are no USB devices. More... /dev/sda is the first USB device; /dev/sdb is the second, and so on. /dev/sda1 is the first partition on the first device; /dev/sda2 is the second partition, etc.

5. Insert the USB drive into your router. Enter ls -al /dev/sd* again, and this time you should see a new /dev/sdXX device. This is the name of your new USB device.

  root@OpenWrt:~# ls -al /dev/sd*
  brw-------    1 root     root        8,   0 Feb  4 15:13 /dev/sda
  brw-------    1 root     root        8,   1 Feb  4 14:06 /dev/sda1

6. Make an ext4 filesystem on the USB device using the name of the new USB device. Note: Be certain you enter the proper device name - this step will completely erase the device. More... This example creates an ext4 file system on the first partition of the first USB device - /dev/sda1.

mkfs.ext4 /dev/sda1

7. Update the fstab config file based on all the block devices found. More... This command writes the current state of all block devices, including USB drives, into the /etc/config/fstab file.

block detect | uci import fstab

8. Ensure the new drive will be mounted at startup. More... /dev/sda is mount[0], /dev/sdb is mount[1], etc. If you have more than one USB device attached, substitute the proper index (0 or 1 or …) as needed.

uci set fstab.@mount[0].enabled='1' && uci set fstab.@global[0].check_fs='1' && uci commit

9. Mount the device and enable the fstab service so the new configuration will be applied after a reboot.

/sbin/block mount && service fstab enable

10. You're done! By default, this procedure mounts the drive at /mnt/sdxx (whatever the device name was.) The drive is ready to save data at that part of the filesystem. You can change the mount point in the web interface, in System → Mount Points menu, or look fstab for configuring from the command line.

If you want more information about this procedure, see the full USB Drive tutorial. Or check the forum article that contains background information for this note at: https://forum.openwrt.org/t/more-on-usb-drive-installation/30695/2