RPI Image not utilizing all available space

So I was doing my round of updating all my Linux boxes and I was having quite a bit of trouble from the modbro-raspberry pi. Constantly disconnecting my SSH sessions, extremely slow input lag.

I didn't check free diskspace at first. No, my first step was to create a swapfile, because the RPI was really slow and unresponsive and I thought it was having memory issues.

I couldn't even create a 1GB swapfile, because the disk was full.

Upon checking, I found this:

Filesystem      Size  Used Avail Use% Mounted on
/dev/root       2.7G  2.7G     0 100% /
devtmpfs        459M     0  459M   0% /dev
tmpfs           464M  4.2M  459M   1% /dev/shm
tmpfs           464M  6.2M  457M   2% /run
tmpfs           5.0M  4.0K  5.0M   1% /run/lock
tmpfs           464M     0  464M   0% /sys/fs/cgroup
none             10M  196K  9.9M   2% /var/log
/dev/mmcblk0p1  253M   53M  200M  21% /boot
tmpfs            93M     0   93M   0% /run/user/1001

This not being my first RPI, I knew what to do, but it would be nice if the Modbro setup would go through this automatically.

What you need to do, is run “sudo raspi-config”, go to "Advanced Options" and select “Expand Filesystem”.

I had to do this twice in a row, because the first attempt threw an error (lack of diskspace), the 2nd time it did work.

After rebooting my RPI, the entire memorycard was finally being used (check the root size):

Filesystem      Size  Used Avail Use% Mounted on
/dev/root        15G  3.9G   10G  28% /
devtmpfs        459M     0  459M   0% /dev
tmpfs           464M  6.2M  457M   2% /dev/shm
none             10M     0   10M   0% /run
tmpfs           464M     0  464M   0% /sys/fs/cgroup
none             10M  200K  9.9M   2% /var/log
/dev/mmcblk0p1  253M   53M  200M  21% /boot

After this step, the performance and responsiveness improved drastically (obviously).

This can easily be automated by running a single command “raspi-config --expand-rootfs”, followed by a reboot.