New operating system default in HTC system TODAY October 17

[chtc-users@xxxxxxxxxxx]

Greetings CHTC users,

For users of our HTC system: Today's the day that all CHTC-managed submit servers will now allow your jobs to run on Scientific Linux 6 or CentOS 7, instead of our previous default of Scientific Linux 6 only. This change is now reflected in our operating system transition guide: http://chtc.cs.wisc.edu/os-transition

If your jobs have been running fine up to this point, they should continue to do so without requiring that you take any additional action. Please let us know if you experience otherwise.Â

Best,

Your CHTC team

---------- Forwarded message ----------
From: <chtc-users@xxxxxxxxxxx>
Date: Wed, Oct 4, 2017 at 3:56 PM
Subject: New operating system default in HTC system, October 17; please read
To: chtc-users <chtc-users@xxxxxxxxxxx>

Greetings CHTC users,

This message is for all users of our high throughput computing (HTC) system.

CHTC staff are continuing to upgrade the computers in our HTC system to a newer version of Linux, as described in this guide.

Up to now, HTC jobs submitted from CHTC-managed submit servers have required (by default) that they only run on execute servers with our Scientific Linux 6 operating system. Users have been able to also run on our newer operating system (CentOS 7) by opting in as we transition more execute servers to this new version. In two weeks, this default will change.Â

On October 17, all CHTC submit servers will be configured to allow submitted jobs to run on either operating system version unless you specify that they require only one of these.

CHTC jobs that have been running on Scientific Linux 6 will also be able to run on the newer CentOS 7 without errors (based upon our own tests and the experiences of users who have tried running on the newer CentOS 7). We anticipate that most users should be able to continue submitting jobs as usual without any changes.

If you are interested in testing your jobs on the new operating system (just to make sure they'll work), or if you otherwise know that your jobs cannot run on both operating systems, read on:

• If you want to test your jobs to make sure they will run successfully on CentOS 7, you can test a subset of your jobs by adding the following submit file line:
  requirements = (OpSysMajorVer == 7)
• If you already have a "requirements" statement specifying a specific "OpSysMajorVer", that requirement will override the defaults we set on the submit servers, so your jobs will only run on the OpSysMajorVer number(s) you have specified.
  
• For those who will need to run on only Scientific Linux 6 or only on CentOS 7 in the future, you will be able to specify a single operating system by using the same requirement described above, with the appropriate operating system version.Â
  

If you experience a situation where code that you've compiled on our Scientific Linux 6 servers (the current default) fails when running on CentOS 7 servers, please let us know immediately!Â

Email questions or concerns to chtc@xxxxxxxxxxx.

Best,
Your CHTC team

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