Hydra supports a bunch of daemon processes, including ssh. There is a daemon process included with MPICH called "persist", which you could use for this purpose, but it's not really maintained. You could try it. -- Pavan From: unix haha Reply-To: "[email protected]<mailto:[email protected]>" Date: Tuesday, June 30, 2015 at 6:18 PM To: "[email protected]<mailto:[email protected]>" Subject: [mpich-devel] about MPI hydra process management Hi, all: I'm working on port the MPICH2 3.1.4 to an embedded environment. I met some problems for hydra process management, Could anyone help me? 1. For the old MPD, before the mpirun, there's a daemon process running on all computer nodes. But I don't see what's hydra's daemon process in the current MPI document. Could you give me some hints? 2. As we run the MPICH2 in a resource constraint environment, the SSH or the other linux-based launcher may not be used. Does it exist any simple launcher running on the computer nodes before the mpiexec? 3. What's my understanding for hydra is: once the Launcher process running on all computer nodes, I can use the mpiexec on the control node to start the parallel jobs? If so, the problem is: Could I start the Launcher process manually if there's no linux-based launcher? Thanks!