Extroot configuration
How to use a storage device (usb or sata or sdcard or whatever) to expand your LEDE device's space in root filesystem, to install freely all the packages you need.
Some background information
In most supported devices, the LEDE firmware splits the internal storage in two partitions, a highly-compressed read-only partition which is the actual root filesystem (/), the second partition is writable, called “overlay” (/overlay).
The overlay partition is merged with the root filesystem using the overlayfs feature of linux kernel, showing a single “whole” read-write filesystem to applications.
This way LEDE fits even in tiny amounts of internal storage (as low as 4 MiB), but still allows to write settings and install some packages in the writable partition without changing all linux programs used.
Extroot works by setting another overlay partition in the external storage device, and during boot this new overlay partition will be mounted over the internal storage's overlay partition. This approach allows easy fallback in case the external storage device is removed, as your LEDE device will still have its own overlay partition and thus will load all configuration from there.
Which means that it will behave exactly the same as just before you set up extroot.
The overlay partition is merged with the root filesystem using the overlayfs feature of linux kernel, showing a single “whole” read-write filesystem to applications.
This way LEDE fits even in tiny amounts of internal storage (as low as 4 MiB), but still allows to write settings and install some packages in the writable partition without changing all linux programs used.
Extroot works by setting another overlay partition in the external storage device, and during boot this new overlay partition will be mounted over the internal storage's overlay partition. This approach allows easy fallback in case the external storage device is removed, as your LEDE device will still have its own overlay partition and thus will load all configuration from there.
Which means that it will behave exactly the same as just before you set up extroot.
First stage for devices with 8 MiB or more internal space
These devices should have enough space to install the packages we need. Remove all packages you have installed to add functionality, as they are only wasting space now. After you made the extroot you will have all space you need.
From the command line interface write (on a single line):
opkg update && opkg install block-mount kmod-fs-f2fs kmod-usb-storage mkf2fs f2fsck kmod-usb-ohci kmod-usb-uhci fdisk
Common second stage
Connect with ssh to the device.
See what partitions you have:
root@lede:/# block info /dev/mtdblock2: UUID="9fd43c61-c3f2c38f-13440ce7-53f0d42d" VERSION="4.0" MOUNT="/rom" TYPE="squashfs" /dev/mtdblock3: MOUNT="/overlay" TYPE="jffs2" /dev/sda1: UUID="fdacc9f1-0e0e-45ab-acee-9cb9cc8d7d49" VERSION="1.4" TYPE="f2fs"
here we see mtdblock devices (partitions in internal flash memory), and a partition on /dev/sda1 that is on a usb flash drive (in the example it is already formatted as f2fs)
We now first format the external drive as f2fs or ext4.
For f2fs:
root@lede:/# mkfs.f2fs /dev/sda1
For ext4:
root@lede:/# mkfs.ext4 /dev/sda1
Then we transfer the content of the current overlay inside the external drive
root@lede:/# mount /dev/sda1 /mnt ; tar -C /overlay -cvf - . | tar -C /mnt -xf - ; umount /mnt
Automated fstab generation
Now we create automatically the fstab uci subsystem and fill it with the right configuration to have /dev/sda1 as new overlay
root@lede:/# block detect > /etc/config/fstab; \ sed -i s/option$'\t'enabled$'\t'\'0\'/option$'\t'enabled$'\t'\'1\'/ /etc/config/fstab; \ sed -i s#/mnt/sda1#/overlay# /etc/config/fstab; \ cat /etc/config/fstab;
If you have a swap partition it will also get recognized and added automatically.
Check if overlay is mountable
let's try manually mounting to see if everything is OK
root@lede:/# mount /dev/sda1 /overlay
now we see mount point sizes:
root@lede:/# df
this is an example output:
Filesystem 1K-blocks Used Available Use% Mounted on rootfs 896 244 652 27% / /dev/root 2048 2048 0 100% /rom tmpfs 14708 64 14644 0% /tmp /dev/mtdblock6 7759872 477328 7221104 6% /overlay overlayfs:/overlay 896 244 652 27% / tmpfs 512 0 512 0% /dev /dev/sda1 7759872 477328 7221104 6% /overlay
Note that only
/overlay has grown but not the /Final steps
root@lede:~# mount /dev/root on /rom type squashfs (ro,relatime) proc on /proc type proc (rw,noatime) sysfs on /sys type sysfs (rw,noatime) tmpfs on /tmp type tmpfs (rw,nosuid,nodev,noatime) /dev/mtdblock6 on /overlay type jffs2 (rw,noatime) overlayfs:/overlay on / type overlay (rw,noatime,lowerdir=/,upperdir=/overlay/upper,workdir=/overlay/work) tmpfs on /dev type tmpfs (rw,relatime,size=512k,mode=755) devpts on /dev/pts type devpts (rw,relatime,mode=600) /dev/sda1 on /overlay type ext4 (rw,relatime,data=ordered) /dev/sda3 on /data type ext4 (rw,relatime,data=ordered) debugfs on /sys/kernel/debug type debugfs (rw,noatime)
root@lede:~# df Filesystem 1K-blocks Used Available Use% Mounted on rootfs 7759872 477328 7221104 6% / /dev/root 2048 2048 0 100% /rom tmpfs 14708 64 14644 0% /tmp /dev/mtdblock6 7759872 477328 7221104 6% /overlay overlayfs:/overlay 7759872 477328 7221104 6% / tmpfs 512 0 512 0% /dev /dev/sda1 7759872 477328 7221104 6% /overlay /dev/sda3 242846048 163864 230323224 0% /data
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