10.0 Requesting an Interactive Node

10.1 Introduction

This guide provides step-by-step instructions on how to request an interactive node on the Sun Grid Engine (SGE) cluster.

Open a Terminal
- Access your terminal application on your local machine or connect to the cluster via SSH.
Load the Required Modules (if necessary)
- Depending on your environment, you may need to load specific modules. Use the following command:
```
module load <module_name>
```
Request an Interactive Session
- Use the qlogin command with the -pe option to request an interactive session. You can specify the resources you need (e.g., number of slots, time limit) as follows:
```
qlogin -pe mpi 64 -l mem_free=4G -l h=hostname
```
- Replace 4G with the desired memory and hostname with the specific node you want to use (example compute-0-0).
Specify Additional Options (Optional)
- You can add more options to customize your request, such as:
  - -q queue_name: Specify the queue.
  - -l h_rt=01:00:00: Set the maximum run time (1 hour in this example).
Connect to the Interactive Node
- Once your request is accepted, you will be connected to the interactive node, and you can start executing your commands.
End the Interactive Session
- To exit the interactive session, simply type:
```
exit
```

Open a Terminal
- Access your terminal application on your local machine.
Connect to the Cluster with X11 Forwarding
- Use the ssh command with the -X option to enable X11 forwarding. Replace username and cluster_address with your actual username and the address of the cluster (e.g. quevedo.eaifr.org):
```
ssh -X username@quevedo.eaifr.org
```
Load the Required Modules (if necessary)
- If VMD is not installed by default, load the necessary module:
```
module load vmd
```
Launch VMD
- Start VMD by typing the following command:
```
vmd
```
Use VMD for Visualization
- Once VMD is open, you can load your molecular structures and begin your visualization tasks.
End the VMD Session
- To exit VMD, simply close the application window or type:
```
exit
```

Login to CINECA’s HPC Infrastructure can be configured to ease access. See :doc:Section 11 <cineca_access>

For further assistance, please refer to the cluster documentation or contact the ICTP-EAIFR research support team.