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docs(hpc): add storage overview, cache redirect instructions, update smoke test path

- Add storage table ($VSC_HOME / $VSC_DATA / $VSC_SCRATCH) with guidance
- Document cache redirect requirement in interactive sessions
- Update smoke test path to configs/hpc/smoke_test.yaml
- Describe train.pbs output staging behaviour
This commit is contained in:
Tibo De Peuter 2026-04-04 18:39:53 +02:00
parent 7bcfa66685
commit cd2e594d1b

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@ -6,17 +6,49 @@ Full documentation: <https://docs.hpc.ugent.be/>
Choose the appropriate cluster before submitting a job with `module swap cluster/<name>`. The default login cluster is **doduo**.
| Cluster | Type | Use case |
|-----------|-------------------------|-----------------------------------------------|
| `donphan` | Interactive / debug GPU | First-time setup, interactive debugging |
| `doduo` | CPU (default login) | Rapid iteration, CPU-only smoke tests |
| `joltik` | GPU (A100 ¼-slice) | Standard training runs |
| `accelgor`| GPU (A100 full) | Large-scale / long experiments |
| `litleo` | GPU | Alternative GPU option |
> **Rule:** use at most **1 GPU per group at a time** on shared GPU clusters.
> Check the current queue load at <https://shieldon.ugent.be:8083/pbsmon-web-users/>.
---
## Storage Overview
The HPC provides three filesystems for different purposes. Understanding this is critical to avoid filling up your home directory.
| Variable | Typical size | Purpose |
|-----------------|-------------|------------------------------------------------------|
| `$VSC_HOME` | ~3 GB | Config files, SSH keys, project source code only |
| `$VSC_DATA` | ~25 GB | Persistent outputs: trained models, final logs |
| `$VSC_SCRATCH` | Large | Fast I/O during jobs: caches, intermediate files |
**Important:**
- Clone the repository into `$VSC_HOME` — it is small in size and accessible from all clusters.
- All caches (pip, uv, matplotlib) must be redirected to `$VSC_SCRATCH` to avoid filling `$VSC_HOME`.
- Run outputs are written to `$VSC_SCRATCH` during the job (fast I/O) and copied to `$VSC_DATA` at the end for persistence.
- `$VSC_SCRATCH` may be purged periodically — do not use it as long-term storage.
Check your quota: <https://account.vscentrum.be> (Usage section).
---
## Initial Environment Setup
Run **once** from a login node after cloning the repository:
Run **once** from a login shell on `donphan` after cloning the repository:
```bash
# 1. Connect via the web portal → HPC Login → Interactive Apps > Shell (tmux)
# Set cluster to "donphan (interactive/debug)"
# 2. Clone the project (if not done yet)
# 2. Clone the project into $VSC_HOME (if not done yet)
cd $VSC_HOME
git clone <repo-url>
cd 2026SEL3-project-BrittleStar
@ -24,29 +56,45 @@ cd 2026SEL3-project-BrittleStar
bash scripts/hpc/install.sh
```
> **Note:** virtual environments are cluster-specific. Re-run the script if you switch to a new cluster.
This uses the official [`vsc-venv`](https://docs.hpc.ugent.be/Linux/setting_up_python_virtual_environments/#vsc-venv-python-virtual-environment-wrapper-script) wrapper to:
- Redirect caches to `$VSC_SCRATCH` (to preserve your `$VSC_HOME` quota)
- Load the EasyBuild modules listed in `env/hpc/modules.txt` (JAX, Flax, WandB, …)
- Create a per-cluster virtual environment in `$VSC_DATA`
- Pip-install the remaining packages from `env/hpc/requirements.txt`
- Register a Jupyter kernel named `SEL3 (<cluster>)`
> **Note:** virtual environments are cluster-specific. Re-run the script when switching to a new cluster.
---
## Interactive Debugging on donphan
The `donphan` cluster provides quick access to a fractional A100 GPU and is ideal for verifying your environment end-to-end before submitting batch jobs.
The `donphan` cluster provides quick access and is ideal for verifying your environment before submitting batch jobs.
### Option A — Interactive shell session
```bash
# Swap to the debug cluster (from the login node)
# Swap to the debug cluster (from any login node)
module swap cluster/donphan
# Request an interactive job (1 node, 4 cores)
qsub -I -l nodes=1:ppn=4 -l walltime=1:00:00
# Once inside the job, activate your environment
cd "$PBS_O_WORKDIR" # or cd to your project root if not set
# Once inside the job — redirect caches to scratch first
export XDG_CACHE_HOME="$VSC_SCRATCH/.cache"
export UV_CACHE_DIR="$VSC_SCRATCH/.cache/uv"
export MPLCONFIGDIR="$VSC_SCRATCH/.config/matplotlib"
# Change to the project directory and activate environment
cd "$PBS_O_WORKDIR"
module load vsc-venv
source vsc-venv --activate --modules env/hpc/modules.txt
# Run the smoke test
# Set headless rendering backend
export MUJOCO_GL=egl
python src/train.py --config configs/hpc_smoke_test.yaml
# Run the smoke test
python src/train.py --config configs/hpc/smoke_test.yaml
```
### Option B — JupyterLab session (HPC web portal)
@ -54,13 +102,13 @@ python src/train.py --config configs/hpc_smoke_test.yaml
1. In the web portal go to **Interactive Apps → JupyterLab RHEL9**
2. Set the following options:
| Option | Value |
|---------------------|---------------------------------|
| Cluster | `donphan (interactive/debug)` |
| Number of nodes | 1 |
| Number of cores | 4 |
| JupyterLab version | `4.2.5 GCCcore-13.3.0` |
| Custom code | *(leave blank — vsc-venv handles modules)* |
| Option | Value |
|---------------------|-------------------------------------------------|
| Cluster | `donphan (interactive/debug)` |
| Number of nodes | 1 |
| Number of cores | 4 |
| JupyterLab version | `4.2.5 GCCcore-13.3.0` |
| Custom code | *(leave blank — vsc-venv handles modules)* |
3. Click **Launch**, wait for the session to start, then **Connect**.
4. In JupyterLab, select the kernel **`SEL3 (<cluster>)`**.
@ -74,6 +122,8 @@ python src/train.py --config configs/hpc_smoke_test.yaml
> **Warning:** JAX can only be loaded by one kernel at a time. Shut down other kernels before switching notebooks.
---
## Submitting Batch Training Jobs
```bash
@ -85,6 +135,12 @@ module swap cluster/accelgor
qsub scripts/hpc/train.pbs
```
The job script automatically:
- Redirects all caches to `$VSC_SCRATCH`
- Writes run outputs to `$VSC_SCRATCH/runs/<job_id>` during the run
- Copies final results to `$VSC_DATA/runs/<job_id>` on completion
- Writes PBS stdout/stderr to `$VSC_DATA/runs/<job_id>/job.out` / `job.err`
Monitor your jobs:
```bash
@ -93,13 +149,11 @@ qstat -f <id> # detailed info for a specific job
qdel <id> # cancel a job
```
Logs are written to `runs/pbs_<jobid>.out` and `runs/pbs_<jobid>.err`.
---
## Managing Dependencies
`env/hpc/requirements.txt` is the **source of truth** for pip packages on the HPC. It is automatically regenerated by CI whenever `pyproject.toml` changes. To regenerate locally:
`env/hpc/requirements.txt` is auto-generated by CI whenever `pyproject.toml` changes. To regenerate locally:
```bash
uv run scripts/export_hpc_requirements.py