Using USB Storage with the Omega

The Omega can read and write to USB storage devices, such as USB keys, and USB external hard-drives. This tutorial will show you how to manually mount and unmount storage, and then how to setup automatic mounting.

This tutorial is on how to use USB drive as separate storage device. If you want to use the USB storage device as Rootfs (i.e. if you want to install opkg packages on the USB storage device), then read [[Tutorials/Using-USB-Storage-as-Rootfs]].

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Supported Filesystems

The following filesystems are currently supported:

• FAT32
• NTFS
• ext2, ext3, ext4

Let us know if you have any requests!

Using USB Storage

Steps to setup USB storage manually:

1. Plug in the USB Storage
2. Usually, it will get mapped to the sda1 device
   • Double check the mapping:
     • ls /dev/sda*
   • It should output something like:
     • /dev/sda /dev/sda1
   • Usually it will get mapped to sda1
3. Create a mount point directory
   • mkdir /mnt/sda1
4. Mount the drive
   • mount <device> <mount point>
   • for example: mount /dev/sda1 /mnt/sda1/ * The storage can now be accessed at /mnt/sda1

Safely Removing USB Storage

The USB storage must be unmounted before safely removing the disk.

The umount command is used to unmount the storage

umount <mount point>

From the above example:

umount /mnt/sda1

The USB device can now be safely unplugged.

Automatic Mounting

Manually mounting everytime becomes pretty tedious after a while… Luckily, Linux has a built-in utility to automatically mount drives when they are plugged in.

Setting up Automatic Mounting for a Drive

Let’s take a look at our fstab configuration, this is the configuration file that holds all of the storage device info on the system. It can be found at /etc/config/fstab, meaning we can access it with UCI:

root@Omega-267F:~# uci show fstab
fstab.@global[0]=global
fstab.@global[0].anon_swap='0'
fstab.@global[0].anon_mount='0'
fstab.@global[0].auto_swap='1'
fstab.@global[0].auto_mount='1'
fstab.@global[0].delay_root='5'
fstab.@global[0].check_fs='0'

Setup a New Device

Now, plug in the drive.

Then, we will need to detect the information for the drive and save it in our fstab configuration:

block detect > /etc/config/fstab

Now the Omega has an fstab UCI entry for this specific USB drive. Let’s update the UCI entry so that it will automatically be mounted.

First, let’s see the current configuration by running uci show fstab, it will output something like the following:

fstab.@global[0]=global
fstab.@global[0].anon_swap='0'
fstab.@global[0].anon_mount='0'
fstab.@global[0].auto_swap='1'
fstab.@global[0].auto_mount='1'
fstab.@global[0].delay_root='5'
fstab.@global[0].check_fs='0'
fstab.@mount[0]=mount
fstab.@mount[0].target='/mnt/sda1'
fstab.@mount[0].uuid='1806-3FEB'	// this is the unique identifier of the USB drive
fstab.@mount[0].enabled='0'

Now, lets enable the mount[0] device:

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

Make sure fstab is Enabled

Just to be safe, let’s enable fstab to run at boot:

/etc/init.d/fstab enable
block mount

Restarting fstab

Any time the fstab configuration is changed, the following command can be used to restart the process so the changes will take effect:

block umount;block mount

Summary

That’s it! Now this particular USB drive will be automatically mounted whenever it’s plugged in, or if it’s present at boot.

Enjoy!

Safely Removing USB Storage

Even when automatically mounting a USB drive, it still has to be unmounted before it’s unplugged:

block umount

What’s Next?

Now that your USB drive is mounted, you can use it to store all sorts of different data. For instance, you can set it up so the Omega’s root filesystem is run from the USB device. You can also setup a Samba share so that users on your local network can access the USB drive wirelessly. It’s really up to you!

Happy hacking!