Move /home directory (or any other) to a dedicated partition

Sometimes your disk will get full. That’s the sad reality of life. So one solution can be to move a directory, like /home for example, to dedicated partition on another drive. Good news is, you can do this on a running system, without a single reboot…

Also, I assume that you already created the new the new partition using something like GParted.

1. Create the filesystem

If not done yet (with GParted for example), create the filesystem, and don’t forget to indicate the correct partition path:

sudo mkfs.ext4 /dev/nvme0n1p1

2. Copy the files to the new partition

sudo mkdir /mnt/temp
sudo mount -t ext4 /dev/nvme0n1p1 /mnt/temp

and

sudo rsync -av /home/ /mnt/temp/

The -a (archive) option is important as it will preserve file properties (owner, group, creation time etc.)

3. Find the UUID of the new partition

lsblk -f -e7

4. Modify /etc/fstab

You can now add the new partition to /etc/fstab, using the UUID of the partition:

UUID=1c765...       /home   ext4    errors=remount-ro       0       2

As we modified /etc/fstab, we must relad systemd to take modifications into account:

sudo systemctl daemon-reload

5. Mount the new partition and test

And now we can mount the new partition:

sudo mount /home

And test!

6. Remove files from the original partition

Now here is the trick: the files are still present on the original partition (and thus consuming space), but ‘hidden’ under the freshly mounted partition.

The remove them, we can ‘bind mount’ the root directory in /mnt/bind for example, so we can access and delete the files from the original partition:

sudo mkdir /mnt/bind
sudo mount --bind / /mnt/bind

And delete the files:

sudo rm -Rf /mnt/bind/home/*

Moving a directory to a dedicated partition on another drive can be a lifesaver when dealing with a full disk. This process can be accomplished on a running system without the need for a reboot, making it a convenient solution for system administrators and users alike. But remember to carefully follow each step, including modifying the directory and partition paths to match your specific setup, and taking necessary precautions to avoid data loss.

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