Clariden is a vcluster (versatile software-defined cluster) that's part of the Alps system.

A short summary of the hardware available in the nodes: 

Each node consists of 4xGH200 superchips. Each superchip is a unified memory system consisting of a Grace CPU and a Hopper GPU with a 900GB/s NVLINKC2C connect. The Grace CPUs share 512GB of LPDDR5X memory. Each individual Hopper GPU has 96GB of HBM3 memory with 3000GB/s read/write, totaling 896GB of unified memory available within each node.

More information on the available partitions can be found with scontrol show partitions.

Access and Accounting

• Clariden can be reached via ssh from the frontend Ela ( `ssh <username>@ela.cscs.ch`). The access to CSCS services and systems requires users to authenticate using multi-Factor Authentication (MFA). Please, find more information here.
• Account and Resources Management Tool
• Usage policies

Connecting to Clariden

Clariden can be accessed by ssh -A ela  (which is a frontend) and from then, ssh clariden.

It's possible to create a shh tunnel to Clariden via Ela. The following must be add in your personal computer's ~/.ssh/config file (replacing <username> by your CSCS user name)

Host ela
 Hostname ela.cscs.ch
 User <username>
 AddKeysToAgent yes
 ForwardAgent yes
Host clariden
 Hostname clariden.cscs.ch
 User <username>
 ProxyJump ela
 IdentityFile ~/.ssh/cscs-key
 User <username>

Now you should be able to access clariden directly with ssh clariden .

Running Jobs

• Clariden uses the Slurm  workload manager to manage the job scheduling.

• Some typical/helpful slurm commands are

  sbatch	submit a batch script
  squeue	check the status of jobs on the system
  scancel	delete one of your jobs from the queue
  srun	launch commands in an existing allocation
  srun --interactive --jobid <jobid> --pty bash	start interactive session on an allocated node

• Example of Slurm job script

  #!/bin/bash -l
  
  #SBATCH --job-name=<jobname>
  #SBATCH --time=00:15:00
  #SBATCH --nodes=1
  #SBATCH --ntasks-per-core=1
  #SBATCH --ntasks-per-node=4
  #SBATCH --cpus-per-task=16
  
  srun executable

• Please note that the Slurm scheduling system is a shared resource that can handle a limited amount of batch jobs and interactive commands simultaneously. Therefore users are not supposed to submit arbitrary amounts of Slurm jobs and commands at the same time.

Files system

• Storage in Clariden

Software

• We encourage to run the software in Clariden via containers. Jobs using containers can be easily setup and submitted thanks to the Container Engine service.
• To build images see Building container images on Alps
• Running multi-node jobs with NCCL and RCCL