When you reinstall or update Ollama with curl -fsSL `https://ollama.com/install.sh | sh` on Linux, if the models are not in the default folder, add the environment variable to the service file /etc/systemd/system/ollama.service with the following line: 

Environment="OLLAMA_MODELS=/mnt/ollama_models" 

Then, run: 

sudo systemctl daemon-reload 
sudo systemctl restart ollama 

The models will be restored.