How to Fix: SSH error: Temporary failure in name resolution on mpi run

The SSH error 'Temporary failure in name resolution' occurs when the hostname of a slave computer cannot be resolved by the master machine, preventing the execution of parallel MPI jobs. This issue affects users running NAMD computational chemistry software using OpenMPI on multiple computers with static IPs.

This error can be frustrating because it causes the job to fail, even though SSH connections are established successfully. To resolve this issue, we will investigate the possible root causes and provide two primary fix methods.

💡 Why You Are Getting This Error

• The first main reason why this error happens is due to a mismatch between the hostname in the /etc/hosts file of the master machine and the actual hostname of the slave computers. Although SSH connections are established successfully, the hostname resolution fails because the master machine cannot find the correct IP address associated with the slave computer's hostname.
• Another alternative reason could be related to the network configuration or DNS settings on the slave computers that prevent them from resolving their hostnames correctly.

🔧 Proven Troubleshooting Steps

🎯 Final Words

To resolve the SSH error 'Temporary failure in name resolution', update the /etc/hosts file of the master machine to ensure accurate hostname resolution, or use fully qualified domain names (FQDNs) instead of hostnames in the mpi-hostfile. By following these steps, users can resolve this issue and successfully execute parallel MPI jobs on their cluster.