# SO:UK Data Centre Systems

```{toctree}
:maxdepth: 2
:hidden:
:glob:

systems/*
```

## Worker nodes at Blackett

As the SO:UK Data Centre is part of Blackett, we have access to [its Tier-2 services](https://www.blackett.manchester.ac.uk/services/). This means by default when we submit jobs from HTCondor, we can have access to the facility as well, where its main users are from ATLAS and LHCb.

For more details of our current testbed, see [](#System-specifications).

### Wall-clock time

Copied from [Feedback on user documentation · Issue #14 · simonsobs-uk/data-centre](https://github.com/simonsobs-uk/data-centre/issues/14).

- There's a maximum wall-clock time configured. It's currently **72 hours**, jobs get killed if they exceed this.
- The same is true for CPU time for each requested CPU (ie job gets killed if `total used CPU hours > requested CPUs * 72 hours`)
- Need to check how the machine count fits into this, we'll most likely have to update the configuration to take this into account (ie `machine count * requested CPUs * 72 hours`).

### `/tmp` directory

Different HTCondor processes sees a different `/tmp` directory, even when they lands on the same physical nodes. `/tmp` is actually a symlink to somewhere within scratch there, and scratch is unique to each HTCondor process.

I.e. you do not need to worry our tarball method which rely on `/tmp` will clashes with other HTCondor process.

## SO:UK Data Centre worker nodes (Coming Soon)

:::{note}
Unless stated otherwise, as SO:UK Data Centre is part of Blackett, everything from the last section should applies here. SO:UK-Data-Centre-worker-nodes specific details and differences will be put here.
:::

## Submit node

Our submit node is `vm77`, a single, small VM instance for submitting jobs. This is where you ssh into.

## JupyterHub (Coming Soon)

See [Establishing a Dedicated Login Node for Interactive Computing and JupyterHub Integration · Issue #31 · simonsobs-uk/data-centre](https://github.com/simonsobs-uk/data-centre/issues/31).