Ganymede, named after Jupiter’s largest satellite, is a Cyberinfrastructure Research Computing (CIRC) cluster built on the condo model. While Ganymede does have free-to-use queues available to all UT Dallas researchers, a majority of the computational power is provided by nodes purchased for exclusive group access.

For information about purchasing nodes to add to Ganymede, email

Ganymede node setup

Ganymede is set up to run only one job per node. When a user submits a job, they will be given exclusive access to the entire node, regardless of how many cores or how much memory is requested. The following partitions are available by default:

Queue Name Number of nodes Cores (CPU Architecture) Memory Time Limit ([d-]hh:mm:ss)



16 (Intel Sandy Bridge)

32 GB




16 (Intel Sandy Bridge)

32 GB




16 (Intel Sandy Bridge)

128 GB




20 (Intel Ivy Bridge)

256 GB




16 ( Intel Haswell)

256 GB


The above resources only account for a fraction of the compute capacity of Ganymede. All nodes cluster-wide considered, Ganymede has nearly 7300 CPU cores and 36 TB of RAM.

Ganymede storage

Ganymede has two user-writable storage directories, accessible from the head node ( and the compute nodes:

Directory Filesystem Type Network Speed Filesystem Size User Quota (Soft/Hard) Backup Frequency



1/10 gigabit/s[1]

5 TB

50/55 GB


~/scratch (via /scratch/ganymede)

40/56/100 gigabit/s[2]


200 TB

10 TB



/home, due to its small quota, serial nature (recall that it’s exported via NFS) and slower speed, is recommended to be used for scripts, runfiles, and smaller output files. Please don’t run jobs from /home as the filesystem and network can be easily saturated, reducing user experience for others. MPI jobs read and write a lot of data, so just a single multi-node MPI job can slow the /home filesystem drastically.

Recall from the chart that /home is backed up nightly. Backups run nightly to facilitate restoration of users' files in the event file deletion or corruption occurs. If you need a backup restored email {circ-support-email} as soon as possible and a CIRC team member will assist you however they can in getting your files back.


Ceres is the primary high-performance Parallel File System (PFS) for CIRC High Performance Computing (HPC) resources. Currently, Ceres is accessible from Ganymede and Ganymede2.


Ceres is based on the Weka parallel filesystem. This filesystem is software-defined, with client and server-side processing.

On both the client and server side, container technology is utilized.

Note: On clients, a single core is dedicated to the Weka container. This means that on a 24-core system, only 23 cores are available for processing jobs.


Ceres is hosted on Dell servers, namely PowerEdge R7515 NVMe servers and ECS500 spinning disk enclosures to reduce pressure on the flash storage.

The networking consists of 200 gigabit/s (HDR) Infiniband to export to clusters via the WekaFS protocol and 25 gigabit/s Ethernet to export to other systems via the NFS protocol.

Attached Clusters


Ceres exports to Ganymede as /scratch/ganymede, with soft links provided as ~/scratch. On the cluster side:

Directory Filesystem Type Network Speed Filesystem Size User Quota (Soft/Hard) Backup Frequency

~/scratch (via /scratch/ganymede)

40/56/100 gigabit/s[3]


200 TB

10 TB[4]


Please notate in the preceding chart that ~/scratch is NOT BACKED UP IN ANY FORM OR FASHION. Any important data should NOT be stored on the Ganymede Scratch filesystem. Important data should be stored in your home directory, or if applicable, your MooseFS /work directory. While we generally ask users to voluntarily clean up ~/scratch, we reserve the right to purge scratch at any time. If you need assistance, please email


Ceres exports to Ganymede2 as /scratch/ganymede2, with soft links provided as ~/scratch. On the cluster side:

Directory Filesystem Type Network Speed Filesystem Size User Quota (Soft/Hard) Backup Frequency

~/scratch (via /scratch/ganymede2)

200 gigabit/s


20 TB

1 TB[5]



On Ganymede and Ganymede2, ~/scratch is best utilized for high I/O and "larger than 50 GB" datasets, TEMPORARILY. Please utilize the scratch space as "copy to, run, clean up when done" space. The filesystem is a shared resource amongst all Ganymede users and needs to be kept as clean as possible for performance and usability reasons.

Note the network speeds are 40/56/100/200 gigabit/s rather than 1/10/25 gigabit/s. This is due to the network link being Infiniband as opposed to Ethernet; Infiniband is a much faster and much lower latency (0.5 us as opposed to 5-10 ms) than Ethernet. This allows much faster file access (near-instantaneous) when running jobs and ~1.3 GB/s file read/write, which is about 10 times faster than the "standard" link to Ganymede’s /home and . Also, due to its parallel nature, the filesystem doesn’t get saturated as easily as /home, which allows more users to run jobs at the same time. MPI jobs are no issue for ~/scratch, so it’s highly advised to use that space for running jobs, whether parallel or serial.

If you need persistent data storage in addition to the temporary scratch space, please contact with the amount of storage you need, how long you need it, and what your workloads are and a CIRC team member will work with you to determine how best to proceed.


Recall from above, ~/scratch is NOT BACKED UP. Repeat, the entire Ceres filesystem is NOT BACKED UP. Any data on Ceres can be considered as volatile, so if it’s important please move it off when your job is complete. The hardware running the storage is robust, but nothing is invincible so please be cautious with data storage.


As Ceres is a shared resource by many, we ask that everyone cleans up their data when their jobs have finished, they no longer need it, or if it’s been copied to an external file system.


We are not currently offering buy-ins to Ceres to prevent labs from having significant investment stake into the highly volatile filesystem.

Using Ganymede

Logging in

Ganymede is accessed via SSH. Once your account is activated, you can connect to Ganymede at For example, in a typical terminal client run the command:

ssh <NetID>

More information on setting up SSH access to CIRC machines on your computer can be found here.

Submitting jobs

Information on submitting jobs to Ganymede can be found here. However, there is one Slurm variable that should not be included in your submission script:

#SBATCH --account=<NetID>

Attempting to run a Slurm submission script with this variable results in:

[user@ganymede ~]$ sbatch
sbatch: error: Batch job submission failed: Invalid account or account/partition combination specified

This error can usually be fixed by removing the --account flag in your batch script.

Users and accounts are separate concepts in Slurm. Your NetID is a user ID, not an account.

TACC Launcher

Multiple instances of serial programs can run on Ganymede via TACC Launcher. To use, load the launcher module in your submission script:

# Loads the Launcher Module
module load launcher

The TACC webpage has more information on running Launcher jobs.

DO NOT use Launcher with MATLAB. MATLAB at UT Dallas is run by a central license server (not run by CIRC) and queuing up many simultaneous MATLAB jobs will crash the license server and break MATLAB for everyone at UT Dallas.

Using containers

Many "bundled" codes are distributed via Docker containers. Docker is not allowed on CIRC systems due to security issues. However, Docker containers can be used by running them with Apptainer/Singularity. For example, you can use the TensorFlow Docker container from DockerHub with the following commands:

# Loads the Singularity Module
module load singularity

# Pull the TensorFlow Docker container and transform
# it into a Singularity sandbox
singularity build --sandbox tensorflow_sandbox/ docker://tensorflow/tensorflow

# Run your Python script with the tensorflow container
singularity run -u --nv tensorflow_sandbox python <>

Available software

You can view all available modules on Ganymede by running the command module spider. If you need new software installed or a different version than is provided, please contact

1. Most Ganymede nodes have a 1 gigabit/s connection to `/home`; however some privately accessible nodes have a 10gigabit/s connection. The file server itself exports the filesystem via a 10 gigabit/s link.
2. The `smallmem` queue utilizes a 40gigabit/s link whereas the `normal` and `debug` queues utilize a 56gigabit/s link. Some privately accessible nodes utilize a 100gigabit/s link. The storage appliance itself exports the filesystem at 100gigabit/s.
3. The `smallmem` queue utilizes a 40 gigabit/s link whereas the `normal` and `debug` queues utilize a 56 gigabit/s link. Some privately accessible nodes utilize a 100 gigabit/s link. The storage appliance itself exports the filesystem at 200 gigabit/s.
4. Due to the high capital investment of Ceres and a relatively small amount of space being purchased, all Ganymede users have a 10 TB quota on the filesystem to prevent any one user from utilizing more than 5% of the available space. If you require a larger quota, please email
5. Due to the high capital investment of Ceres and a relatively small amount of space being purchased, all Ganymede2 users have a 1 TB quota on the filesystem to prevent any one user from utilizing more than 5% of the available space. If you require a larger quota, please email