Hoffman2:Interactive Sessions: Difference between revisions
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==Basic Command== | ==Basic Command== | ||
To get one, you need to use the <code>qrsh</code> command | To get one, you need to use the <code>qrsh</code> command. | ||
For example | For example | ||
$ qrsh | $ qrsh | ||
will try to get you an interactive node | will try to get you an interactive node. | ||
Because you didn't specify a time limit this session will only last two hours after which you will be kicked off of the interactive node back to a login node. | Because you didn't specify a time limit this session will only last two hours after which you will be kicked off of the interactive node back to a login node. | ||
And because you didn't specify a memory limit, | And because you didn't specify a memory limit, the default is 1GB. | ||
If you successfully get a node, your prompt will change from something like | If you successfully get a node, your prompt will change from something like | ||
Line 28: | Line 26: | ||
[joebruin@n1234 ~] $ | [joebruin@n1234 ~] $ | ||
indicating you are on node 1234. | indicating you are on node 1234. | ||
==Longer Time== | ==Longer Time== |
Revision as of 21:25, 14 November 2017
Interactive sessions on Hoffman2 let you have access to a computing node for up to 24 hours. This is ideal for:
- running a intensive program like MATLAB (in fact that's how it works), WEKA, R or FSLView
- debugging a script you will be submitting to the queue later
- moving/tar'ing/untar'ing lots of files
- any other computing or graphics intensive operations
since you aren't supposed to use the login nodes for such heavy lifting.
Basic Command
To get one, you need to use the qrsh
command.
For example
$ qrsh
will try to get you an interactive node.
Because you didn't specify a time limit this session will only last two hours after which you will be kicked off of the interactive node back to a login node.
And because you didn't specify a memory limit, the default is 1GB.
If you successfully get a node, your prompt will change from something like
[joebruin@login4 ~] $
to something like
[joebruin@n1234 ~] $
indicating you are on node 1234.
Longer Time
If you wanted to specify a a time limit for your interactive session (anything less than 24 hours), use the resource flag again and specify time in the HH:MM:SS format.
For example
$ qrsh -l i,h_rt=4:00:00
will try securing an interactive node for four hours with the default amount of RAM, but if they are all taken you will be kindly told you are out of luck.
More Memory
Doing something memory intensive? Like working with a lot of visualizations or multiple datasets? Use the resource flag again and specify a data request.
For example
$ qrsh -l i,h_rt=4:00:00,h_data=4G
will try securing an interactive node for four hours with four gigabytes of RAM, but if no such node is available the cluster will deny your request.
Tips
Sometimes inactivity on your computer will result in Hoffman2 connection break [ Broken Pipe ] (even while computing).
To prevent this from happening: For Macs - in your /etc/ssh_config -add this line to the bottom
ServerAliveInterval 180
This will tell your ssh to ping the server every 180 seconds to prevent it from timing out.