113
edits
Difference between revisions of "Cluster SSH access"
Jump to navigation
Jump to search
→Testing Cluster Access
(Created page with " == Cluster SSH Access == Most cluster applications will be controlled using the SSH protocol. In order for this to work, you will have to set up SSH keys in your math acco...") |
|||
| (One intermediate revision by one other user not shown) | |||
|
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.
Don't worry if they differ by one second, because the time may have changed during the command. If they differ by more than a second, there may be a problem, but it should not effect most commands.
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[57-64] 'uptime'
Or other computation hosts where you have keys set up, such as fibonacci and ramsey:
pdsh -R ssh -w fibonacci,ramsey 'uptime'
Once you have these commands working, you're ready to configure your distributed application.
| |||