How to keep the process running on remote server even if the ssh connection is closed?
You can use screen to detach a session. You connect to your ssh server, launch screen and then your computation...
At your next connection, screen -a
to attach previous sessions
see : http://www.bangmoney.org/presentations/screen.html
You can run your process/command inside a screen or tmux session, Or you can do:
yourcmd &
disown