Colima disk full: check usage and reclaim space

Part of: Docker disk space on Mac: Docker.raw, images and build cache explained (Docker)

If Colima says the disk is full, the space is almost always used by Docker data inside the VM: images, build cache, stopped containers and volumes. Look first with two read-only commands, remove what you can pull or build again, and only then think about a bigger disk.

Colima is a tool that runs Docker in a small Linux virtual machine (VM) on your Mac. The VM has its own disk with a fixed size, so it can be full while your Mac still has plenty of space.

Check what is using the space

Make sure Colima is running and the Docker command points at it. Then run:

docker system df

You get one row each for images, containers, local volumes and build cache, with a total size and a reclaimable amount. docker system df -v lists the individual items. In my test on Colima 0.10.3 both worked, and the output included a Build Cache row; that row is our observation, not something Docker’s reference page states.

To see the size the VM disk was set up with, run:

colima list

On our Colima install the output had a DISK column showing the configured size; the Colima docs do not document that column. To see how full the disk is from the inside, colima ssh -- df -h / runs a normal disk-usage check in the VM. On our install it printed the filesystem size and the used and available space; this is our observation, not a documented command.

Where Colima keeps its data on your Mac

The Colima FAQ says it stores its data in $HOME/.colima by default, and you can change that with the COLIMA_HOME environment variable. To see how large that folder is on your Mac, run:

du -sh ~/.colima

On my Colima 0.10.3 install, the VM disk is a single large file below ~/.colima/_lima/_disks/. That layout is not described in the FAQ and may differ between versions, so treat it as an observation, not a rule.

Like Docker.raw, that file is sparse: ls -lh shows the configured limit and du -h shows what is really used. The Docker.raw guide explains the difference.

What to remove

Docker’s pruning guide describes a separate prune command for containers, images, volumes and build cache, and says volume pruning leaves named volumes alone unless you add an option. The overview explains a calm order, and the build cache guide covers the cache.

Will the space come back to the Mac?

Freeing space inside the VM and getting it back on your Mac are two steps. The Colima FAQ says that for version 0.5.0 and above, “unused disk space in the VM is released on startup”. It also describes a manual option, running fstrim inside the VM, for the same purpose. For Colima 0.4.x or earlier, it says freed VM space is not reflected on the host.

So after you remove data, restarting Colima is the documented way to let the Mac reclaim it. I did not test the fstrim route, so I do not give a command for it here.

If you need a bigger disk

The Colima README says the default VM has 100 GiB of storage, that you can choose a size with the --disk option when you create it, or edit the configuration file, and that the “disk size can be increased after the VM is created”. It does not describe shrinking the disk, so plan on growing only. Look at the README for the exact current syntax before you change anything.

Starting over with a new VM removes every image and container in the old one, so treat that as a last resort.

Quick checklist

1. Run colima list to see the configured disk size.
2. Run docker system df to see which kind of data is biggest.
3. Remove what you can pull or build again.
4. Restart Colima so unused space is released, if your version supports it.
5. Only then consider a bigger disk.

How DiskJoy fits in

DiskJoy is our product. It is pre-alpha: it scans your Mac and shows what is reclaimable, with allocated sizes rather than the maximum a sparse file claims. It does not look inside the Colima VM and it does not remove anything, because cleanup is not built yet. The download page shows the current status of the scan.