What is the Caviness Cluster and Why Should You Use it?

Overview

Teaching: 25 min
Exercises: 5 min

Questions

• What is the Caviness Cluster and who can use it?

• What can I expect to learn from this course?

Objectives

• Understand the basics about the Caviness Cluster, who are its owners and who can use it.

• Identify how the Caviness Cluster could benefit your research.

• Know how Caviness may differ from other High Performance Computing (HPC) Systems but also other clusters here at the University of Delaware

What is the Caviness Cluster?

The Caviness cluster is named in honor of Jane Caviness, the former director of Academic Computing Services at the University of Delaware. In the 1980’s, Jane Caviness led a groundbreaking expansion of UD’s computing resources and network infrastructure that laid the foundation for UD’s current research computing capabilities.

Caviness is University of Delaware’s (UD) third community cluster. It was deployed in July 2018 and is a distributed-memory Linux cluster. It is based on a rolling-upgradeable model for expansion and replacement of hardware over time. For more information on the specifics of Caviness hardware please vist the Caviness page. The cluster was purchased with a proposed 5 year life for the first generation hardware, putting its refresh in the April 2023 to June 2023 time period.

Caviness is a technical and financial partnership between UD’s Information Technologies and UD’s faculty and researchers who require high-performance computing resources. Faculty and researchers become financial stakeholders by purchasing HPC resources (based on the cost of one or more compute nodes) in the cluster. Only stakeholders and the researchers sponsored by a stakeholder may use the cluster. It is located at UD’s Computing Center.

Why Use The Caviness Cluster

What do you need?

Talk to your neighbor about your research. How does computing help you do your research? How could more computing help you do more or better research?

Frequently, research problems that use computing can outgrow the desktop or laptop computer where they started:

• A statistics student wants to do cross-validate their model. This involves running the model 1000 times – but each run takes an hour. Running on their laptop will take over a month!
• A genomics researcher has been using small datasets of sequence data, but soon will be receiving a new type of sequencing data that is 10 times as large. It’s already challenging to open the datasets on their computer – analyzing these larger datasets will probably crash it.
• An engineer is using a fluid dynamics package that has an option to run in parallel. So far, they haven’t used this option on their desktop, but in going from 2D to 3D simulations, simulation time has more than tripled and it might be useful to take advantage of that feature.

In all these cases, what is needed is access to more computers that can be used at the same time. Luckily, large scale computing systems – shared computing resources with lots of computers – like Caviness can be use to help with these problems. HPC systems similar to Caviness can be found at many other universities, labs, or through national networks. These resources usually have more central processing units(CPUs), CPUs that operate at higher speeds, more memory, more storage, and faster connections with other computer systems. They are frequently called “clusters”, “supercomputers” or resources for “high performance computing” or HPC. In this lesson, we will usually use the terminology of HPC and HPC cluster.

Using a cluster often has the following advantages for researchers:

• Speed. With many more CPU cores, often with higher performance specs, than a typical laptop or desktop, HPC systems can offer significant speed up.
• Volume. Many HPC systems have both the processing memory (RAM) and disk storage to handle very large amounts of data. Terabytes of RAM and petabytes of storage are available for research projects.
• Efficiency. Many HPC systems operate a pool of resources that are drawn on by a many users. In most cases when the pool is large and diverse enough the resources on the system are used almost constantly.
• Cost. Bulk purchasing and government funding means that the cost to the research community for using these systems is significantly less than it would be otherwise.
• Convenience. Maybe your calculations just take a long time to run or are otherwise inconvenient to run on your personal computer. There’s no need to tie up your own computer for hours when you can use someone else’s instead.

This is how a large-scale compute system like a cluster can help solve problems like those listed at the start of the lesson.

Thinking ahead

How do you think using a large-scale computing system will be different from using your laptop? Talk to your neighbor about some differences you may already know about, and some differences/difficulties you imagine you may run into.

Caviness Cluster compared to the other clusters at UD and other HPC systems.

The workload management software on Caviness is Slurm. It is commonly used for HPC systems but it is new to UD. The prior two community clusters used Grid Engine for their workload manager. For setting up your computing environment Caviness will continue to use VALET, just as Mills and Farber have used. VALET is a recursive acronym for VALET Automates Linux Environment Tasks – is an alternative that strives to be as simple as possible to configure your environment to use software installed on the cluster. VALET is unique to UD, if you have used another HPC system you might be familiar with the Environment Modules Package, more commonly known as modules. VALET and modules essentially perform the same services, but each have a different syntax in doing so. More details on VALET will be coming later on in the course.

On Command Line

Using Caviness like most HPC systems involves the use of a shell through a command line interface (CLI) and either specialized software or programming techniques. The shell is a program with the special role of having the job of running other programs rather than doing calculations or similar tasks itself. Whatever the user types, is passed to the shell, which then figures out what commands to run and orders the computer to execute them. (Note that the shell is called “the shell” because it encloses the operating system in order to hide some of its complexity and make it simpler to interact with.) The most popular Unix shell is Bash, the Bourne Again SHell (so-called because it’s derived from a shell written by Stephen Bourne). Bash is the default shell on most modern implementations of Unix and in most packages that provide Unix-like tools for Windows.

Interacting with the shell is done via a command line interface (CLI) on most HPC systems. In the earliest days of computers, the only way to interact with early computers was to rewire them. From the 1950s to the 1980s most people used line printers. These devices only allowed input and output of the letters, numbers, and punctuation found on a standard keyboard, so programming languages and software interfaces had to be designed around that constraint and text-based interfaces were the way to do this. Typing-based interfaces are often called a command-line interface, or CLI, to distinguish it from a graphical user interface, or GUI, which most people now use. The heart of a CLI is a read-evaluate-print loop, or REPL: when the user types a command and then presses the Enter (or Return) key, the computer reads it, executes it, and prints its output. The user then types another command, and so on until the user logs off.

Learning to use Bash or any other shell sometimes feels more like programming than like using a mouse. Commands are terse (often only a couple of characters long), their names are frequently cryptic, and their output is lines of text rather than something visual like a graph. However, using a command line interface can be extremely powerful, and learning how to use one will allow you to reap the benefits described above.

The rest of this lesson

The only way to use these types of resources is by learning to use the command line. This introduction to Caviness has two parts:

• We will learn to use the UNIX command line (also known as Bash).
• We will use our new Bash skills to connect to and operate a high-performance computing supercomputer.

The skills we learn here have other uses beyond Caviness or other HPC: Bash and UNIX skills are used everywhere, be it for web development, running software, or operating servers. It’s become so essential that Microsoft now ships it as part of Windows! Knowing how to use Bash and HPC systems will allow you to operate virtually any modern device. With all of this in mind, let’s connect to a cluster and get started!

Key Points

• Caviness is like other HPC systems but does use a custom program (VALET) for setting up the computing environment.

• Caviness and HPC systems can be used to do work that would either be impossible or much slower on a local desktop or lab computer.

• The standard method of interacting with most HPC systems is via a command line interface such as Bash.