Guide to Using the Center for High-Performance Computing (CHPC) at the University of Utah

This guide outlines the workflow for effectively utilizing the CHPC resources at the University of Utah. It covers setting up your environment, connecting to CHPC, managing interactive sessions, and tips for efficient computation.

1. Set Up Your CHPC Account

1.1. Set Bash as Your Default Shell

Log in to the CHPC User Portal:
- Navigate to https://www.chpc.utah.edu/role/user/edit_profile.php.
- Enter your UNID and password to log in.
Change Your Shell:
- Locate the "Shell in General Environment" option.
- Select "/bin/bash" from the dropdown menu.
- Click "Submit" to save your changes.

2. Connect to CHPC via SSH

2.1. SSH Connection Basics

SSH URL Format:
- Use the following format to connect to CHPC clusters:
```
ssh unid@cluster[1,2].chpc.utah.edu
```
  - Replace unid with your University of Utah ID.
  - Replace cluster with the name of the cluster you wish to access (e.g., ash or notch).
  - Optionally, specify 1 or 2 to connect to a specific cluster (e.g., cluster1 or cluster2).
Examples:
- Connect to the default cluster (load balancer will assign you to the preferred cluster):
```
ssh [email protected]
```
- Connect to a specific cluster (e.g., cluster1):
```
ssh [email protected]
```
GUI Alternative:
- For users who prefer a graphical interface, FastX is available. Visit https://www.chpc.utah.edu/ for more information.
Windows Users:
- Enable OpenSSH Client (built into Windows 10 and later).
- Alternatively, download and use PuTTY or FastX.

3. Add the Interactive Helper Command to Your Profile

3.1. Edit Your Bash Profile

Open the Bash Profile:
- Use nano to edit your ~/.bashrc file:
```
nano ~/.bashrc
```
Add the Interactive Helper Function:
- Scroll to the bottom of the file and paste the following function:

interactive ()
{ 
    local DEFAULT_ARGS=(--account="$1" --partition="$2" --nodes=1 --ntasks-per-node=1 --cpus-per-task=4 --mem=64G --time="$3" --gres=gpu:1);
    local EXTRA_ARGS=();
    local DO_NOTIFY=0;
    local num_fixed_args=3;
    local args_copy=("$@");
    local extra_args_start_index=-1;
    local i=0;
    while (( i < ${#args_copy[@]} )); do
        if [[ "${args_copy[$i]}" == "--notify" ]]; then
            DO_NOTIFY=1;
            unset 'args_copy[i]';
            args_copy=("${args_copy[@]}");
            continue;
        fi;
        if [[ "${args_copy[$i]}" == "--" ]]; then
            extra_args_start_index=$((i + 1));
            break;
        fi;
        i=$((i + 1));
    done;
    if [[ $extra_args_start_index -ne -1 ]]; then
        EXTRA_ARGS=("${args_copy[@]:$extra_args_start_index}");
    fi;
    declare -A arg_map;
    for arg in "${DEFAULT_ARGS[@]}";
    do
        key="${arg%%=*}";
        arg_map["$key"]="$arg";
    done;
    for extra_arg in "${EXTRA_ARGS[@]}";
    do
        key="${extra_arg%%=*}";
        arg_map["$key"]="$extra_arg";
    done;
    if [[ -v arg_map["--gres"] ]]; then
        local gres_value="${arg_map["--gres"]}";
        if [[ "$gres_value" == "--gres" || "$gres_value" == "--gres=" ]]; then
            unset arg_map["--gres"];
        fi;
    fi;
    local final_args=();
    for key in "${!arg_map[@]}";
    do
        final_args+=("${arg_map[$key]}");
    done;
    local remote_command="";
    if (( DO_NOTIFY == 1 )); then
        remote_command="push_to_mobile 'chpc-notification' 'Interactive Queue Ready' & ";
    fi;
    remote_command+="exec bash";
    if [ -z "${DEBUG+x}" ]; then
        salloc "${final_args[@]}" srun --pty /bin/bash -l -c "${remote_command}";
    else
        echo "salloc ${final_args[@]} srun --pty /bin/bash -l -c \"${remote_command}\"";
    fi
}

Save and Exit:
- Press Ctrl + O to save.
- Press Ctrl + X to exit.
Apply Changes:
- Reload your Bash profile:
```
source ~/.bashrc
```

4. Start a Tmux Session

4.1. Why Use Tmux?

Persistent Sessions: Tmux allows you to detach and reattach to your session, making it ideal for long-running jobs.
Multiple Windows/ Panes: Tmux supports multiple windows and panes for organizing your workflow.

4.2. Start a New Tmux Session

Create a New Session:
```
tmux new -s my_session
```
- Replace my_session with a meaningful name for your session.
Detach from the Session:
- Press Ctrl + B, then D to detach.
Reattach to the Session:
```
tmux attach -t my_session
```

5. Request an Interactive Session

5.1. Use the Interactive Helper Function

Inside a Tmux Session:
- Ensure you are inside your tmux session before requesting an interactive session.
Request Resources:
- Use the interactive function to request an interactive session:
```
interactive my_account main_partition 01:00:00
```
  - Replace:
    - my_account with your CHPC account name.
    - main_partition with the partition (queue) you want to use.
    - 01:00:00 with your desired walltime in HH:MM:SS format.
Customize Resource Requests (Optional):
- Override default arguments by adding extra parameters:
```
interactive my_account main_partition 01:00:00 -- --nodes=2 --mem=128G
```
Additonal Usage Instructions (Optional):
- See additional usage instructions here: https://gist.github.com/richbai90/a6f28ef8257335b38f89d3af07bb174a

6. Detach and Reattach to Your Session

Detach from Tmux Session:
- Press Ctrl + B, then D to detach from your tmux session.
Reattach Later:
- Reattach to your session when you are ready to resume work:
```
tmux attach -t my_session
```

7. Additional Tips and Resources

7.1. Monitoring Your Job

Use squeue -u unid to monitor your job status.
Use sacct to view historical job information.

7.2. Accessing Storage

Home Directory: /uufs/chpc.utah.edu/common/home/unid
Scratch Space: plan to use /scratch for temporary storage.

7.3. Getting Help

Visit the CHPC Documentation for more resources.
Contact CHPC support at [email protected].

By following this guide, you can efficiently utilize CHPC resources for your computational needs.

richbai90/CHPC Guide.md

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