Logging Into Arc from a Linux or Mac Desktop/Laptop

You can connect to Arc using your myUTSA ID (abc123) and an SSH client or terminal. Two-factor authentication is required; therefore, you will need to register your account with DUO at passphrase.utsa.edu

The complete SSH command is as follows (replace abc123 with your actual myUTSA ID):

ssh abc123@arc.utsa.edu

When you connect, you will be prompted to choose a DUO authentication method as shown below. Enter the number corresponding to your preferred option, follow the directions on your mobile device, and you will then be connected to Arc.

|Duo two-factor login for abc123
|
|Enter a passcode or select one of the following |options:
|
| 1. Duo Push to XXX-XXX-1234
| 2. Phone call to XXX-XXX-1234
| 3. SMS passcodes to XXX-XXX-1234
|
| Passcode or option (1-3):

After logging into Arc, you are placed on one of two login nodes, selected at random. On these nodes, you may edit files, transfer data, and submit batch jobs, but compute- or memory-intensive tasks are not allowed.

To run software interactively, you must first obtain a compute node using the following command:

srun -p partition-name -n 1 -t hh:mm:ss -c 40 --pty bash

Where

partition-name must be one of the valid partitions on Arc. The public partitions are listed in the following table.

-n 1 specifies that one concurrent task will be launched in the session, which is the default setting for non-MPI applications.

-t hh:mm:ss defines the duration of the session. The session will automatically terminate once the specified time expires. The maximum runtime for most partitions on Arc is 72 hours, except for compute2, where jobs can run up to 240 hours. Private partitions have no runtime limit.

Partition Name	Partition Type	Number of Nodes	Number of CPU Cores Per Node	Memory Size	Runtime Limit
compute1	Public CPU	65	40 Xeon(R) Gold 6248 @ 2.50GHz	384GB	72 Hours
compute2	Public CPU	27	40 Xeon(R) Gold 6248 @ 2.50GHz	384GB	240 Hours
compute3	Public CPU	6	16 AMD EPYC 7F32 @3.6GHz	1TB	72 Hours
gpu1v100	Public GPU	22	40 Xeon(R) Gold 6248 @ 2.50GHz One V100-32GB	384GB	72 Hours
gpu2v100	Public GPU	9	40 Xeon(R) Gold 6248 @ 2.50GHz Two V100-32GB	384GB	72 Hours
gpu4v100	Public GPU	2	40 Xeon(R) Gold 6248 @ 2.50GHz Four V100-32GB	384GB	72 Hours
gpu1a100	Public GPU	2	16 AMD EPYC 7F32 @3.6GHz One A100-40G	1TB	72 Hours
bigmem	Public CPU	2	80 Xeon(R) Gold 6248 @ 2.50GHz	1.5TB	72 Hours
bigmem2	Public CPU	1	16 AMD EPYC 7F32 @3.6GHz	2.1TB	72 Hours

There are also privately owned partitions on Arc, including softmatter, dgxa100, uavlab, uavlab2, and trustlab. Access to these partitions is restricted and requires prior authorization.

Logging Into Arc From a Windows Desktop/Laptop

Windows does not have a built-in SSH client suitable for HPC use, so users need to install a third-party SSH client to log into Arc. We recommend MobaXterm, an excellent SSH client for HPC users that simplifies remote access, integrates file transfer and graphical display, and provides a familiar Linux-like experience.

Please follow the steps below:

1. Download the free home edition of MobaXterm at https://mobaxterm.mobatek.net/download.html and install it on your Windows system.

2. After installing MobaXterm on Windows, launch the program. The following window will appear.​

3. Click “Session”, then select “SSH” in the new window.

• Enter arc.utsa.edu as the Remote Host.

• Enter your myUTSA ID (abc123).

• Click “OK.”

4. You will then be prompted to enter your password, followed by a DUO two-factor authentication prompt to complete the login process.

​Accessing Arc the Virtual Desktop Through the On-demand Web portal

The Arc On-Demand Web Portal provides an alternative way to access Arc through a convenient web interface. It is especially useful for users who need quick access from systems without SSH client software or who wish to run applications with a Graphical User Interface (GUI).

Detailed instructions can be found here.