Move Docker data on an external drive to free up memory on the main SD card
Move Docker data on an external drive to free up memory on the main SD card
Attempt #1 - Failed
I followed these guides:
- https://thesmarthomejourney.com/2021/02/11/moving-docker-data-to-an-external-ssd/
- https://www.howtogeek.com/devops/how-to-store-docker-images-and-containers-on-an-external-drive/
First list external drives: df.
My output:
File system 1K-blocchi Usati Disponib. Uso% Montato su
/dev/root 7303220 6419724 529608 93% /
devtmpfs 3834192 0 3834192 0% /dev
tmpfs 3999920 204 3999716 1% /dev/shm
tmpfs 1599968 1228 1598740 1% /run
tmpfs 5120 4 5116 1% /run/lock
/dev/mmcblk0p1 261108 31292 229816 12% /boot
tmpfs 799984 516 799468 1% /run/user/1000
/dev/sda1 960302096 28 911447644 1% /media/alcaprar/lacie
Then create a folder where we’ll mount the drive: sudo mkdir /mnt/ext-drive
Mount the drive on the new folder: sudo mount /dev/sda1 /mnt/ext-drive/. This is a temporary mount.
Make the mount permanent:
- Find the drive UUID:
ls -l /dev/disk/by-uuid - Edit
/etc/fstaband add something similar to:UUID=ef63c1cf-6d18-48c3-976d-f8590b8a662d /mnt/ext-drive ext4 defaults 0 0
Add (or change if it exists already) to the /etc/docker/daemon.json:
{
"data-root": "/mnt/ext-drive/docker-data"
}
IMPORTANT: Before proceeding do a backup!!!
Copy the previous docker data into the new folder in the external drive: sudo rsync -aSv /var/lib/docker/ /mnt/ext-drive/docker-data.
Copy the previous volumes data: sudo rsync -aSv ~/self-hosted/data /mnt/ext-drive/self-hosted/data.
Restart docker daemon: sudo service docker restart.
At this point everything should start up without problems and you should have all the data.
Now this is the new output of df:
File system Dim. Usati Dispon. Uso% Montato su
/dev/root 7,0G 5,7G 1,1G 85% /
devtmpfs 3,7G 0 3,7G 0% /dev
tmpfs 3,9G 204K 3,9G 1% /dev/shm
tmpfs 1,6G 1,2M 1,6G 1% /run
tmpfs 5,0M 4,0K 5,0M 1% /run/lock
/dev/mmcblk0p1 255M 31M 225M 12% /boot
tmpfs 782M 516K 781M 1% /run/user/1000
/dev/sda1 916G 464M 869G 1% /mnt/ext-drive
A bit disappointed, only a 8% saving. I will dig into it a bit more in the future.
Since I moved the /var/lib/docker into the external drive I can remove it. This gave only 1% more of free space, better than nothing.
These are my 10 biggest folders: sudo du -aBm / 2>/dev/null | sort -nr | head -n 10
6761M /
3065M /usr
1677M /home/alcaprar
1677M /home
1605M /home/alcaprar/.local/share/docker
1605M /home/alcaprar/.local/share
1605M /home/alcaprar/.local
1598M /home/alcaprar/.local/share/docker/overlay2
1524M /usr/lib
934M /var
The .local/share/docker folder occupies still a lot of space. But I am not sure if it’s still in use or not.
At this point I was not sure that the above worked. This stackoverflow comment helped me to understand that it did not. If I run docker info|grep "Docker Root Dir" I still get Docker Root Dir: /home/alcaprar/.local/share/docker which is not the new folder I configured above.
Attempt #2 - Failed again
I am now going to try this guide. This is what I did:
docker-compose down- backup
datafolder where I bind volumes - backup the
/mnt/ext-drive/docker-datathat I thought Docker is now using:sudo rsync -aSv /mnt/ext-drive/docker-data /mnt/ext-drive/docker-data-backup. Andsudo rm -r /mnt/ext-drive/docker-data && mkdir /mnt/ext-drive/docker-data. - change the
ExecStartline in the service configuration file:sudo vi /lib/systemd/system/docker.serviceto beExecStart=/usr/bin/dockerd --data-root /tmp/new-docker-root -H fd:// --containerd=/run/containerd/containerd.sock - restart docker by running
sudo systemctl daemon-reloadandsudo systemctl restart docker. The restart failed and by runningjournalctl -xeI saw this errorservice-start-limit-hit. I found somewhere that the.jsonconfig could interfeer and I deleted it. After re-running the restart it worked.
At this point I retried the docker info with no luck. It still shows the old folder.
Attempt 3
Let’s start from the beginning and re-install it from scratch.
First of all let’s wipe Docker: https://askubuntu.com/a/1021506.
Now I have a lot of free space finally!
File system Dim. Usati Dispon. Uso% Montato su
/dev/root 7,0G 3,8G 2,9G 58% /
devtmpfs 3,7G 0 3,7G 0% /dev
tmpfs 3,9G 408K 3,9G 1% /dev/shm
tmpfs 1,6G 1,2M 1,6G 1% /run
tmpfs 5,0M 4,0K 5,0M 1% /run/lock
/dev/mmcblk0p1 255M 31M 225M 12% /boot
tmpfs 782M 32K 782M 1% /run/user/1000
/dev/sda1 916G 2,1G 868G 1% /mnt/ext-drive
I used the get script provided in their installation page and after the installation this is the space situation:
File system Dim. Usati Dispon. Uso% Montato su
/dev/root 7,0G 4,2G 2,5G 63% /
devtmpfs 3,7G 0 3,7G 0% /dev
tmpfs 3,9G 408K 3,9G 1% /dev/shm
tmpfs 1,6G 1,2M 1,6G 1% /run
tmpfs 5,0M 4,0K 5,0M 1% /run/lock
/dev/mmcblk0p1 255M 31M 225M 12% /boot
tmpfs 782M 32K 782M 1% /run/user/1000
/dev/sda1 916G 2,1G 868G 1% /mnt/ext-drive
And docker info still shows that root folder.
This time I will create a symlink instead of tweaking the configs:
- Stop docker:
sudo systemctl stop docker.socketandsudo systemctl stop docker - Since it’s a fresh installation there is nothing to move.
- Create the symlink:
ln -s /mnt/ext-drive/docker-data /home/alcaprar/.local/share/docker - Restart docker. I wanted to be sure and I also rebotted.
- Restart the
docker-composeand wait that it downloads all the images again. Evreything is up and working!
And, df -h now shows this:
File system Dim. Usati Dispon. Uso% Montato su
/dev/root 7,0G 4,1G 2,6G 62% /
devtmpfs 3,7G 0 3,7G 0% /dev
tmpfs 3,9G 204K 3,9G 1% /dev/shm
tmpfs 1,6G 1,2M 1,6G 1% /run
tmpfs 5,0M 4,0K 5,0M 1% /run/lock
/dev/mmcblk0p1 255M 31M 225M 12% /boot
/dev/sda1 916G 3,7G 866G 1% /mnt/ext-drive
tmpfs 782M 512K 781M 1% /run/user/1000
Finally / has remained the same and /dev/sda1 has now 1.5 GB more!