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OSG Exercise 1.5: Software Differences in OSG

The goal of this exercise is to see some differences in the availability of software in the OSG. At your local cluster, you may be used to having certain versions of software. But in the OS Pool, it is possible — even likely — that the software you need will not be available at all.

Comparing operating systems

To really see differences between slots in the local cluster vs the OSG, you will want to compare the slot ClassAds between the two pools. Rather than inspecting the very long ClassAd for each slot, you will look at a specific attribute called OpSysAndVer, which tells us the operating system version of the server where a slot resides. An easy way to show this attribute for all slots is by using condor_status in conjunction with the -autoformat (or -af, for short) option. The -autoformat option is like the -format option you learned about earlier, and outputs the attributes you choose for each slot; but as you may have guessed, it does some automatic formatting for you.

So, let’s examine the operating system and (major) version of slots on CHTC and the OS Pool.

  1. Log in or switch to learn.chtc.wisc.edu and run the following command:

    [email protected] $ condor_status -autoformat OpSysAndVer
    
  2. Log in or switch to login04.osgconnect.net (parallel windows are handy!) and run the same command

You will see many values for the operating system and major version. Some are abbreviated — for example, RedHat stands for “Red Hat Enterprise Linux” and SL stands for “Scientific Linux” (a Red Hat variant).

The only problem is that with hundreds or thousands of slots, it's difficult to get a feel for the composition of each pool from this output. You can use the sort and uniq commands, in sequence, on the condor_status output to get counts of each unique operating system and version string. Your command line should look something like this:

[email protected] $ condor_status -autoformat OpSysAndVer | sort | uniq -c

How would you describe the difference between CHTC and OS Pools?

Submitting probe jobs

Now you have some idea of the diversity of operating systems on the OS Pool. This is a step in the right direction to knowing what software is available in general. But what you really want to know is whether your specific software tool (and version) is available.

Software probe code

The following shell script probes for software and returns the version if it is installed:

#!/bin/sh

get_version(){
    program=$1
    $program --version > /dev/null 2>&1
    double_dash_rc=$?
    $program -version > /dev/null 2>&1
    single_dash_rc=$?
    which $program > /dev/null 2>&1
    which_rc=$?
    if [ $double_dash_rc -eq 0 ]; then
        $program --version 2>&1
    elif [ $single_dash_rc -eq 0 ]; then
        $program -version 2>&1
    elif [ $which_rc -eq 0 ]; then
        echo "$program installed but could not find version information"
    else
        echo "$program not installed"
    fi
}

get_version 'R'
get_version 'cmake'
get_version 'python'
get_version 'python3'

If there's a specific command line program that your research requires, feel free to add it to the script! For example, if you wanted to test for the existence and version of nslookup, you would add the following to the end of the script:

get_version 'nslookup'

Probing several servers

For this part of the exercise, try creating a submit file without referring to previous exercises!

  1. Log in or switch to login04.osgconnect.net
  2. Create and change into a new folder for this exercise, e.g. osg-ex15
  3. Save the above script as a file named sw_probe.sh
  4. Make sure the script can be run: chmod a+x sw_probe.sh
  5. Try running the script in place to make sure it works: ./sw_probe.sh
  6. Create a submit file that runs sw_probe.sh 100 times and uses macros to write different output, error, and log files
  7. Submit your job and wait for the results

Will you be able to do your research on the OSG with what's available? Do not worry if it does not seem like you can: Tomorrow, you will learn how to make your jobs portable enough so that they can run anywhere!