Policies

Legion Scheduler

• Tries to give each user an equal share of the machine at any given moment
• Tries to fill gaps with small, short jobs
• Has a few special sets of nodes to run test (short, small) or interactive jobs

"Production"

Anything that uses:

• a lot of CPU time
• a lot of RAM
• a lot of disk access

Production work should be run as a job.

What Can Run

We can provide (stable) application centrally, and compile up software to put in the /shared/ucl/apps space.

You're free to run almost anything that you can build on Legion, though.

Some departments also provide applications, e.g. Chemistry Department: module load chemistry-modules.

We reserve the right to ban the use of applications that prevent or harm other users' use of the cluster.

Limits

Time	Cores	Queue Type
≤ 15 mins	≤1 node	Rapid Test Queue
≤ 1 day	≤ 512 cores	Large Parallel Queue
≤ 2 days	≤ 256 cores	Smaller Parallel Queue
≤ 3 days	1 core	Serial Queue

(Actually more complex than this, check the website.)

Extraordinary Resource Requests

• Grab the form from the website
• Send it to your supervisor/PI to support
• Send it to us: rc-support@ucl.ac.uk
• Wait for approval by the CRAG

Data Policies

Access

• Legion is not a long-term data repository
• Do not store the only copy of your data on Legion

Security

Legion is not suitable for Highly Restricted data and above.

Level	Examples
Secret:	Identifiable patient information
...	Personal financial details
...	Confidential investigations
Highly Restricted:	Student profiles
...	Unpublished commercially sensitive material
Restricted:	UCL main web page
...	Unpublished research data
Normal:	Email about fridge-cleaning meeting

(See: UCL's data security policy)

Security

Responsibility for the accuracy of the results of software installed or available on Legion is the sole responsibility of researchers.

So:

• Test your software
• Check your results

Security

• ssh is the only recommended method to connect to/from Legion
• UCL is not responsible for security of non-UCL machines
• Ensure your machines are reasonably secure

Quotas

• Home directories have a 50 GB quota
• Scratch has a 200 GB quota
  • However you can use as much as you want for up to two weeks
  • After two weeks job submission is disabled until you decrease usage to below quota
• If you need more, we can make small increases (up to double)
  • For more apply to the CRAG

Support Queries

A Good Ticket

Tell us:

• What you're trying to do (technical)
• Exact error output
• Job IDs, scripts, and relevant file paths
• Whether we can look at your files

Keeping Tickets Sane

Subject: Re: Error When Compiling My_App v0.45 (Ref:IN:01287844)

Keeping one ticket ID per problem helps us immensely.

Other Compute Resources

UCL Funded

• Emerald
  • for GPU jobs
• Departmental clusters
  • talk to your local IT manager

Other

• ARCHER
• DIRAC collection
• PRACE
• US National Labs
• EGI
• (Cloud Providers)