FUSE on Linux · CLIO Core

1. Install FUSE 3

Debian, Ubuntu

shell

$ sudo apt install fuse3 libfuse3-3

Fedora, RHEL

shell

$ sudo dnf install fuse3 fuse3-libs

Source build

shell

$ sudo apt install libfuse3-dev fuse3     # or: sudo dnf install fuse3-devel fuse3
$ cmake --preset release-fuse
$ cmake --build build -j"$(nproc)" && sudo cmake --install build

2. Start the runtime and mount

shell

$ clio_run start &
$ mkdir -p ~/clio-mnt
$ CLIO_WITH_RUNTIME=0 clio_cte_fuse ~/clio-mnt -f

The daemon creates or binds the filesystem pool on its own; no extra compose step is needed. CLIO_WITH_RUNTIME=0 attaches it to your runtime, so Python clients and other mounts see the same files.

Every argument after the mountpoint goes to libfuse:

Option	Effect
`-f`	Stay in the foreground. Leave it off to daemonize.
`-d`	Print every FUSE request. Useful for debugging.
`-s`	Single-threaded mode.
`-o allow_other`	Let other users open the mount. Needs `user_allow_other` in `/etc/fuse.conf`.

3. Try it

shell

$ cp -r ~/datasets/era5-sample ~/clio-mnt/
$ du -sh ~/clio-mnt/era5-sample
$ python -c "import numpy as np; print(np.fromfile('$HOME/clio-mnt/era5-sample/t2m.bin', 'f4')[:5])"
$ git clone https://github.com/iowarp/clio-core.git ~/clio-mnt/src   # git works too

4. Unmount

shell

$ fusermount3 -u ~/clio-mnt

Files stay in CLIO Core; mount again to see them. Unmount with fusermount3 -u rather than Ctrl+C: the daemon does not exit on Ctrl+C.

Coherence and caching

Writes always go straight through to the runtime, so sizes are exact after write(). Two settings trade coherence for speed:

Variable	Default	When to change it
`CLIO_FUSE_ATTR_CACHE_S`	1.0 on one node, 0 on several	Set to `0` when several processes on one node modify the same files and must see each other's metadata at once.
`CLIO_FUSE_WRITEBACK`	off	Set to `1` for a single writer doing many small writes. Unsafe with several writers.

Containers and Apptainer

In Docker, the container needs the FUSE device and the capability to mount:

shell

$ docker run --device /dev/fuse --cap-add SYS_ADMIN ...

If something goes wrong

fuse: device not found: the kernel module is not loaded. Run sudo modprobe fuse.
Transport endpoint is not connected: the daemon exited and left a stale mount. Run fusermount3 -u ~/clio-mnt and mount again.
Python does not see the files: the daemon started its own runtime. Mount again with CLIO_WITH_RUNTIME=0.