Docker driver_opts.type=none?

Question

What does type=none do? e.g.

volumes:
  transmission_config:
    driver: "local"
    driver_opts:
      type: "none"

Lots of people are using it but I can't find where any of this is documented.

Where are all the driver options documented?

Answer 1

As explained in the answer from LinPy, the options specified under driver_opts are similar to the options that are used for the mount command.

Looking into what type="none" does in the mount command, I found this answer that says:

The none just means that there is no physical disk partition linked to the mount point you see when issuing the mount command. It is used for virtual filesystems like shm, ramfs, proc and tmpfs.

Which makes sense to use for local Docker volumes as well that are not associated with a specific partition.