Introduction to High Performance Computing ========================================== To begin this unit, we will introduce the basis of high performance computing (HPC), and the general architecture of HPC systems at TACC. We will cover how to log in to an HPC system, and navigate the different file systems available. After going through this module, students should be able to: * Describe the basic architecture of an HPC system * Log in to an HPC system at TACC * Navigate the different file systems available on TACC HPC systems Basic HPC System Architecture ----------------------------- As you prepare to use TACC systems for this unit, 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) .. image:: ./images/hpc_schematic.png :target: ./images/hpc_schematic.png :alt: HPC System Architecture Login vs. Compute Nodes ~~~~~~~~~~~~~~~~~~~~~~~ A typical 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. Tips for Success ~~~~~~~~~~~~~~~~ Read the `documentation `_. * Learn node schematics, limitations, file systems, rules * Learn about the scheduler, queues, policies * Determine the right resource for the job User Responsibility on Shared Resources ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ HPC systems are shared resources. Your jobs and activity on a cluster, if mismanaged, can affect others. TACC staff are always `available to help `_. Log in to Lonestar6 ------------------- To log in to Lonestar6, follow the instructions for your operating system below. Mac / Linux ~~~~~~~~~~~ Open the application 'Terminal' and: .. code-block:: console [local]$ ssh username@ls6.tacc.utexas.edu To access the system: 1) If not using ssh-keys, please enter your TACC password at the password prompt 2) At the TACC Token prompt, enter your 6-digit code followed by . (enter password) (enter 6-digit token) Windows (Use WSL2 or an SSH Client) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Open the application WSL2 : .. code-block:: console [local]$ ssh username@ls6.tacc.utexas.edu To access the system: 1) If not using ssh-keys, please enter your TACC password at the password prompt 2) At the TACC Token prompt, enter your 6-digit code followed by . (enter password) (enter 6-digit token) Or open an SSH client like `PuTTY `_: .. code-block:: console Open the application 'PuTTY' enter Host Name: ls6.tacc.utexas.edu (click 'Open') (enter username) (enter password) (enter 6-digit token) Successful Login to Lonestar6 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ If your login was successful, your terminal will look something like this: .. code-block:: console Last login: Mon Apr 13 16:09:20 2026 from 129.114.111.41 ------------------------------------------------------------------------------ Welcome to the Lonestar6 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 Lonestar6, please read these important system notes: 06/18/2025: /work access has been restored. --> Lonestar6 user documentation is available at: https://portal.tacc.utexas.edu/user-guides/lonestar6 ---------------------- Project balances for user wallen ----------------------- | Name Avail SUs Expires | Name Avail SUs Expires | | TACC-SCI 5933 2026-07-31 | OTH22024 19171 2026-07-31 | | IBN23016 8000 2027-03-31 | IBN22007 1145 2026-09-30 | | DrugDiscovery 6025 2026-05-31 | DBS22003 500 2026-09-30 | | STAR-Avathon 4989 2027-02-28 | OTH24028 525 2029-07-31 | ------------------------- Disk quotas for user wallen ------------------------- | Disk Usage (GB) Limit %Used File Usage Limit %Used | | /scratch 33955.8 0.0 0.00 1692900 0 0.00 | | /home1 7.6 10.0 75.91 56672 0 0.00 | | /work 636.2 1024.0 62.13 2533936 3000000 84.46 | ------------------------------------------------------------------------------- login1.ls6(1001)$ .. note:: The welcome message you receive upon successful login to Lonestar6 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. Another useful way to monitor your disk quotas (and TACC project balances) at any time is to execute: .. code-block:: console [ls6]$ /usr/local/etc/taccinfo .. tip:: Refer back to `Linux Essentials <../unit01/linux_essentials.html>`_ if you need a refresher on navigating Linux file systems. Systems Available at TACC ------------------------- Clusters ~~~~~~~~ * `Frontera `_: The fastest academic supercomputer in the world, providing computational capability that makes larger, more complex research challenges possible. * `Vista `_: Vista expands TACC's capacity for AI and ensures that the broadscience, engineering, and education research communities have access to the most advanced computing and AI technologies. * `Stampede3 `_: The newest strategic resource advancing NSF's supercomputing ecosystem for the nation's open science community. * `Lonestar6 `_: Supporting Texas researchers in providing simulation, data analysis, visualization, and AI/machine learning. * `Jetstream2 `_: A user-friendly, scalable cloud environment with reproducible, sharable computing on geographically isolated clouds. Storage Systems ~~~~~~~~~~~~~~~ * `Corral `_: Storage and data management resource designed and optimized to support large-scale collections and a collaborative research environment. * `Ranch `_: Long-term data archiving environment designed, implemented, and supported to provide storage for data sets of the TACC user community. * `Stockyard `_: Global file system at the center of TACC's system ecosystem that supports data-driven science by providing online storage of large datasets, and offers migration for further data management and archiving. File Systems ~~~~~~~~~~~~ The account-level environment variables ``$HOME``, ``$WORK``, and ``$SCRATCH`` store the paths to directories that you own on each of these file systems. +---------------------+-----------------------------------+--------------------------------------------------------------------------------------------------------------------+ | File System | Quota | Key Features | +=====================+===================================+====================================================================================================================+ | ``$HOME`` |- 10GB |- Backed up. | | | |- Recommended Use: scripts and templates, environment settings, compilation, cron jobs | +---------------------+-----------------------------------+--------------------------------------------------------------------------------------------------------------------+ | ``$WORK`` |- 1TB |- NOT backed up. | | |- 3,000,000 files |- Recommended Use: software installations, original datasets that can't be reproduced. | +---------------------+-----------------------------------+--------------------------------------------------------------------------------------------------------------------+ | ``$SCRATCH`` |- No quota assigned |- NOT backed up. | | | |- Recommended Use: Reproducible datasets, I/O files: temporary files, checkpoint/restart files, job output files | +---------------------+-----------------------------------+--------------------------------------------------------------------------------------------------------------------+ Files in ``$SCRATCH`` are subject to purge if access time is more than 10 days old. Navigating File Systems ~~~~~~~~~~~~~~~~~~~~~~~ To navigate the different file systems available on TACC HPC systems, you can use the standard ``cd`` command along with the ``PATH``, or you can use some TACC-specific shortcuts: 1. **Home Directory**: To change to your home directory, you can use: .. code-block:: console [ls6]$ cd $HOME # or [ls6]$ cd 2. **Work Directory**: To change to your work directory, you can use: .. code-block:: console [ls6]$ cd $WORK # or [ls6]$ cdw 2. **Scratch Directory**: To change to your scratch directory, you can use: .. code-block:: console [ls6]$ cd $SCRATCH # or [ls6]$ cds Additional Resources -------------------- * `TACC Docs `_ * `Lonestar6 Docs `_ * `Unit 1: Linux Essentials <../unit01/linux_essentials.html>`_