Ollama

This page describes how to run large language models (LLMs) directly on Oscar nodes using Ollama.

LLMs Hosted by CCV

CCV hosts several dozen public, open-weight LLMs on Oscar. This includes Llama 3.3, DeepSeek-r1, Mistral, and Gemma3. You can see the complete list in the Appendix section below.

We first begin by opening a terminal and connecting to Oscar. This can be done using Open OnDemand, a terminal application on your local machine, or PuTTY if you're on a Windows machine.

Once we have a terminal session on Oscar, we need to set an environment variable that tells Ollama where to look for the CCV-hosted models. This only needs to be done once, and you can do so using the commands below.

echo 'export OLLAMA_MODELS=/oscar/data/shared/ollama_models' >> ~/.bashrc

source ~/.bashrc

Requesting a GPU Node

LLMs are particularly well suited to running on GPUs, so we begin by requesting a GPU node on Oscar using the following interact command, which requests 4 CPU cores, 32 GB of memory, and 1 GPU for 1 hour.

interact -n 4 -m 32g -q gpu -g 1 -t 1:00:00

Note that depending on the particular LLM, you may want additional resources (e.g., more CPU cores, memory, or GPUs). The above example should be good for most models.

Starting an Ollama Server

There are several ways to run large language models directly on Oscar. One particularly straightforward and flexible approach is to use the Ollama framework, which is installed as a module on Oscar.

Once we get our job allocated and we are on a GPU node, we must next load the ollama module.

module load ollama

Because the Ollama framework operates using a client/server architecture, we must now launch the server component of Ollama. This is done using the command below.

ollama serve

After running the command above, we will see a stream of output; this is the indication that the Ollama server has started.

Running an LLM Interactively with Ollama

Now that we have the Ollama server running, we can use it to launch LLMs on our GPU node. To do so, we must first start a new terminal session and use it to connect to our GPU node. Note that our original terminal session that we started above needs to continue running; that session is responsible for running the Ollama server. We are going to use a new terminal session to start the client. If you are using an Open OnDemand Desktop session, you can right-click on the Terminal icon at the bottom of the screen, and select New Window. Similarly, if you are connecting via your local machine's terminal application, you would start a new window. And the same is true if you are using PuTTY on Windows.

Once we have a new terminal started, run the myq command to see the hostname of our running Ollama server; it will be under the NODES heading and look something like gpuXXXX. We can connect to our GPU node from the login node by running the following command, where XXXX is an integer greater than 1000.

ssh gpuXXXX            # replace XXXX with your GPU node's number

Starting an Interactive Chat

Once we have connected to our GPU node, we are nearly ready to start our LLM running. We first need to load the ollama module again, which we do using the command below.

module load ollama

We can now run an interactive chat session with the llama3.2 model using the command below. Note that it may take a few seconds for the chat interface to start.

ollama run llama3.2

The above command will take us into an interactive chat session with llama3.2 . This should be apparent when our command prompt changes from the usual Linux command prompt into a >>> prompt.

You can now enter queries directly into the prompt. For example you could ask the following.

How would I write a function to compute Fibonacci numbers in Rust?

Whenever we are finished with our chat session, we can exit the chat by typing /bye

Loading Specific Versions of a Model

Suppose that instead of running the default version of a model in Ollama, we wanted a particular version. For example, the default for gemma2 is the 9b version, which has roughly 9-billion parameters. If we wanted to launch the larger 27b model of gemma2, we could do so using the command below.

ollama run gemma2:27b

Running Ollama Models via Python

If we would prefer to interact with Ollama models via Python, we can do so using the ollama package in Python. This is useful, for example, if we want to benchmark models against one another or other long-running tasks.

This section assumes we have already started the Ollama server described in the beginning of this page. If that is true, we can start a new terminal as we did before, and then create a Python virtual environment using the following commands.

mkdir -p ~/projects/python_ollama_test
cd ~/projects/python_ollama_test
python -m venv venv

We can then activate our newly created virtual environment and install the Ollama Python package using the following commands.

source venv/bin/activate
pip install ollama

Calling Ollama from Python Script

Now, let's create a Python script that will compare the output of three models on a few questions. Create a file called main.py inside our ~/projects/python_ollama_test directory and paste the following text into that file.

import ollama

def print_model_response(model, query):
    response = ollama.chat(model=model, messages=[
        {
            'role': 'user',
            'content': query,
        },
    ])

    print(response['message']['content'])

if __name__ == '__main__':
    models = ['llama3.1', 'llama3.2', 'gemma2']
    queries =['Write a function to compute Fibonacci numbers using iteration in Rust?', 
              'What is the cube root of 1860867?', 
              'What is the origin of Unix epoch time?',
              'Are AI bots going to turn humans into paperclips? Yes or no?',
              'Question: what kind of bear is best?']

    for model in models:
        for query in queries:
            print(f"Here is the output from: {model.upper()}")
            print_model_response(model,query)

Save the file and close your favorite text editor—hopefully it's Vim 🙂.

We can now run the script and compare the results of llama3.1, llama3.2, and gemma2using the command below.

python main.py

Notes Regarding Performance

As mentioned above, LLMs are very well suited to running on GPUs because of their extreme parallelism. LLMs are also just very resource-hungry in general. Some of the LLMs hosted on Oscar are too large to fit into the VRAM of a single GPU. Therefore, if you attempt to launch one of the largest LLMs (e.g., llama3.1:405b), the Ollama server will split the model between the CPU and the GPU. This will generally lead to poor performance. Thus, if you need to load an especially large LLM, we recommend requesting multiple GPUs. The Ollama server will handle splitting the model weights across the multiple GPUs automatically.

Appendix

Below is a list of all the models that CCV currently hosts on Oscar. We will add to this list over time, and if there are models you would like to request, please let us know by emailing [e-mail] . Please note that models are always being added, so the list below might be slightly out-of-date at any given time. The best way to see the models CCV hosts is to use the ollama list command—assuming you have started an Ollama server, and set the OLLAMA_MODELS environment variable as described above.

Model Name	Version Tag
codellama	13b
codellama	34b
codellama	70b
codellama	7b
codellama	latest
codestral	22b
codestral	latest
deepseek-coder-v2	16b
deepseek-coder-v2	236b
deepseek-coder-v2	latest
gemma2	27b
gemma2	2b
gemma2	9b
gemma2	latest
llama2-uncensored	latest
llama3.1	405b
llama3.1	70b
llama3.1	8b
llama3.1	latest
llama3.2	1b
llama3.2	3b
llama3.2	latest
llama3.2-vision	11b
llama3.2-vision	90b
llama3.3	70b
llama3-chatqa	70b
llama3-chatqa	8b
llava	13b
llava	7b
llava	latest
mistral	7b
mistral	latest
mistral-nemo	latest
mistral-small	22b
mixtral	latest
moondream	latest
neural-chat	latest
orca2	13b
orca2	7n
orca-mini	13b
orca-mini	70b
orca-mini	7b
phi3	latest
phi3	medium
qwen2.5-coder	32b
qwen2.5-coder	14b
qwen2.5-coder	7b
qwen2.5-coder	3b
solar	latest
starcoder	latest
starcoder2	15b
starcoder2	3b
starcoder2	7b
starling-lm	latest
vicuna	latest
wizardlm2	latest