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Difference between revisions of "Cluster SSH access"
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→Testing Cluster Access
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To test your access to the cluster, you'll use the pdsh command. pdsh uses ssh to send commands in parallel to a group of machines. You have to remember to only send commands that are not going to run for a long time or prompt you for any input, because that will cause your pdsh command to hang as the commands on the other end wait for input that never comes. So, you can send commands like 'uptime' or 'date' that will return output and then exit.
'date' is a good example, it will display the system time on the remote machine and then exit. It's a good idea to run it to make sure all of the remote machines have synchronized clocks. Type the following command: (you may want to stretch the terminal window vertically to see all
pdsh -R ssh -w pnode[01-
This will display the date from each of the remote machines. This should run without errors and come back to a command prompt. If it has errors or does not finish, there may be a problem with either your keys or connectivity to the cluster.
To see how busy the remote machines are, you can do:
pdsh -R ssh -w pnode[01-
which will tell you how long each machine has been up and its system load.
You can use this same command to run things on a subset of nodes, like this command to check the load on the last 8 nodes:
pdsh -R ssh -w pnode[
Or other computation hosts where you have keys set up, such as fibonacci and ramsey:
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