Connecting to the Machines

Basic High Performance Computing (HPC) System Architecture

As you prepare to use TACC systems for this workshop, it is important to understand the basic architecture. Think of an HPC resource as a very large and complicated lab instrument. Users need to learn how to:

Interface with it / push the right buttons (Linux)
Load samples (data)
Run experiments (jobs)
Interpret the results (data analysis / vis)

Login vs. Compute Nodes

As we’ve discussed, an HPC system has login nodes and compute nodes. We cannot run applications on the login nodes because they require too many resources and will interrupt the work of others. Instead, we must submit a job to a queue to run on compute nodes.

Connecting to Frontera

To log in to Frontera, follow the instructions for your operating system below.

Mac / Linux

Open the application ‘Terminal’

[local]$ ssh username@frontera.tacc.utexas.edu
(enter password)
(enter 6-digit token)

Windows

Windows users will need to install an SSH client like PuTTY to follow along. If you have not done so already, download the PuTTY “Windows Installer” here. (Other tools like PowerShell work, too).

Once PuTTY is installed:

Double-click the PuTTY icon
In the PuTTY Configuration window make sure the Connection type is SSH
enter frontera.tacc.utexas.edu for Host Name
click “Open”
answer “Yes” to the SSH security question

In the PuTTY terminal:

enter your TACC user id after the “login as:” prompt, then Enter
enter the password associated with your TACC account
enter your 6-digit TACC token value

Open the application 'PuTTY'
enter Host Name: frontera.tacc.utexas.edu
(click 'Open')
(enter username)
(enter password)
(enter 6-digit token)

Successful Login to Frontera

If your login was successful, your terminal will look something like this:

------------------------------------------------------------------------------
                   Welcome to the Frontera Supercomputer
      Texas Advanced Computing Center, The University of Texas at Austin
------------------------------------------------------------------------------

              ** Unauthorized use/access is prohibited. **

If you log on to this computer system, you acknowledge your awareness
of and concurrence with the UT Austin Acceptable Use Policy. The
University will prosecute violators to the full extent of the law.

TACC Usage Policies:
http://www.tacc.utexas.edu/user-services/usage-policies/
______________________________________________________________________

Welcome to Frontera, please read these important system notes:

--> Frontera user documentation is available at:
       https://portal.tacc.utexas.edu/user-guides/frontera

----------------------- Project balances for user lima ------------------------
| Name           Avail SUs     Expires |                                      |
| TACC-SCI          102149  2025-06-30 |                                      |
-------------------------- Disk quotas for user lima --------------------------
| Disk         Usage (GB)     Limit    %Used   File Usage       Limit   %Used |
| /home1              0.7      25.0     2.90         4752      200000    2.38 |
| /work2             68.4    1024.0     6.68       232978     3000000    7.77 |
| /scratch1           0.0       0.0     0.00            7           0    0.00 |
| /scratch2           0.0       0.0     0.00            1           0    0.00 |
| /scratch3           0.0       0.0     0.00            1           0    0.00 |
-------------------------------------------------------------------------------

Tip 131   (See "module help tacc_tips" for features or how to disable)

   Use Ctrl+E to go the end of the command line.

A Note About Quotas

The welcome message you receive upon successful login to Frontera has useful information for you to keep track of. Especially of note is the breakdown of disk quotas for your account, as you can keep an eye on whether your usage is nearing the determined limit.

Once your usage is nearing the quota, you’ll start to experience issues that will not only impact your own work, but also impact the system for others. For example, if you’re nearing your quota in $WORK, and your job is repeatedly trying (and failing) to write to $WORK, you will stress that file system.

$HOME

is backed up
Recommended Use: cron jobs, scripts and templates, environment settings, compilations

$WORK

NOT backed up
Recommended Use: software installations, original datasets that can’t be reproduced.

$SCRATCH

NOT backed up, subject to purge if access time is more than 10 days old
Recommended Use: Reproducible datasets, I/O files: temporary files, checkpoint/restart files, job output files

Another useful way to monitor your disk quotas (and TACC project balances) at any time is to execute:

[frontera]$ /usr/local/etc/taccinfo