# BSC HPC machines

Providentia's download mode supports downloading **GHOST** and **non-GHOST** observational data, as well as model outputs, directly from BSC HPC systems. 

In order to do this type of download, a BSC HPC account is required.

## Supported HPC login nodes

Providentia can download GHOST and non-GHOST networks from the BSC HPC environment using available login nodes. By default, it connects to `storage5` (or `mn5` if `storage5` is unavailable).  

The login nodes used are defined in `settings/dl_hpc.yaml`:

- `transfer1.bsc.es` (primary)  
- `transfer2.bsc.es`  
- `transfer3.bsc.es`  
- `transfer4.bsc.es`  
- `glogin4.bsc.es`  

Downloads will attempt the nodes in the order listed. If the primary node is unavailable, the system automatically tries the next one in the list.

## Download of networks from HPC machines

The network is essential to generate a report, as it provides access to the real observational data. At BSC, a large number of observational datasets are already stored on `gpfs`.

**Download source paths:**
- Networks are saved under the `ghost_root` and `nonghost_root` paths specified in the `local` key of `settings/data_paths.yaml`.  
- Networks are retrieved from the `ghost_root` and `nonghost_root` paths specified in the `storage5` or `mn5` key of `settings/data_paths.yaml`.

**How to enable:**  
- You must include at least one network in your configuration.  
- Set `dl_mode` to `both` or `obs` (or answer `both`/`obs` to the prompt _"Which type of data do you want to download? Observational, modelled or both?"_).  
- For GHOST network downloads, answer `y` to the prompt:  
  _"Do you want to download observational data from the BSC remote machine? (Otherwise, GHOST observational data will be retrieved from Zenodo)"_  
  or set `dl_ghost_source = bsc` in your configuration.
- **If the configuration file contains only network data and no models, network data will be downloaded automatically.**

## Download of interpolated models

An interpolated model consists of model output that have already been spatially interpolated to the observations. These models are ready to be used in modes such as report and dashboard. Most interpolated model data is stored on `gpfs`.

**Download source paths:**
- Models are saved under the `mod_root` path specified in the `local` key of `settings/data_paths.yaml`.  
- Models are retrieved from the `mod_root` path specified in the `storage5` or `mn5` key of `settings/data_paths.yaml`.

**How to enable:**  
- You must include at least one network and one model in your configuration.  
- Set `dl_mode` to `both` or `mod` (or answer `both`/`mod` to the prompt).  
- Answer `y` to the prompt:  
  _"Model data was detected in the configuration file. Do you want to download the interpolated version? (Otherwise, the non-interpolated model data will be downloaded)"_  
  or set `dl_interpolated = True` in your configuration.

## Download of non-interpolated models

### Local non-interpolated downloads

Non-interpolated model data refers to model outputs that are ready to be interpolated against a network using interpolation mode. Most non-interpolated datasets are stored in `esarchive`, although some may already exist in `gpfs`.

**Download source paths:**
- Models are saved under the `mod_to_interp_root` path specified in the `local` key in `settings/data_paths.yaml`.  
- Models are retrieved from the paths specified in `settings/interp_models.yaml`. To learn how to define models, please see the [Defining models in interp_models.yaml](define-models) section in Interpolation.
- If the model is not in the path, the system looks in the `mod_to_interp_root` paths under the `storage5` or `mn5` key in `settings/data_paths.yaml`.  

**How to enable:**  
- You must include at least one model in your configuration.  
- Set `dl_mode` to `both` or `mod` (or answer `both`/`mod` to the prompt).  
- Answer `n` to the prompt:  
  _"Model data was detected in the configuration file. Do you want to download the interpolated version? (Otherwise, the non-interpolated model data will be downloaded)"_  
  or set `dl_interpolated = False` in your configuration.
- **If the configuration file contains only model data and no networks, non-interpolated model data will be downloaded automatically.**

### HPC non-interpolated downloads
In some cases, model data exists in `esarchive`, but not all HPC machines have direct access to it. When interpolation needs to be performed on a machine without `esarchive` access, the model data must first be copied from `esarchive` to `gpfs`.

**Download source paths:**
- Models are copied from `esarchive` to the `gpfs` `mod_to_interp_root` folder defined under the `storage5` key in `settings/data_paths.yaml`.  
- Only copies from paths specified in `settings/interp_models.yaml`. To learn how to define models, please see the [Defining models in interp_models.yaml](define-models) section in Interpolation.

**How to enable:**  
- The download **must be performed from the `storage5` machine**.

## .env file

An `.env` file will appear in the Providentia root directory when using the download mode. It is designed to store specific user preferences.

   - **PRV_USER:** This setting specifies the username used to connect to the remote machines. It can be any valid username, e.g.: `bsc000000`.
   - **PRV_PWD:** This setting allows you to save the password needed for connecting to remote machines.  
  Note that the password is not required if you have configured a passwordless connection to the different servers.  
  Tutorial: [SSH Key Autologon](https://earth.bsc.es/wiki/doku.php?id=computing:sshkeyautologon&s%5B%5D=id_rsa.pub#ssh_key_autologon) _Only accessible for users with a BSC CAS account._

These values can be changed directly on the `.env` file and also be updated by Providentia during the next run.