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COSMA is comprised of:

  • COSMA5,
  • COSMA7,
  • COSMA8,
  • Storage and support hardware (including tape drives for archival).

COSMA also includes a number of other facilities including:

Storage includes:

  • /cosma5 - 2.4PB
  • /cosma6 - 2.5PB (to be retired in Autumn 2023)
  • /cosma7 - 3.1PB
  • /cosma8 - 5.3PB
  • /snap7 - 440TB for fast temporary storage (e.g. checkpointing)
  • /snap8 - 1.2PB for fast temporary storage (e.g. checkpointing)
  • /cosma/home - 37TB for user homespace (10GB quota)
  • /cosma/local - 37TB for program/module storage

Users have access to /cosma/home/PROJECT/USERNAME, and one or more of /cosmaN/data/PROJECT/USERNAME.

Scratch space

COSMA7 and COSMA8 both contains the /snap[7,8]/ fast I/O storage space, which offers an achievable 180GB/s-400GB/s bandwidth. At installation in 2018, /snap7 this was the fastest storage in Europe.

To make the most of alloted time on COSMA, researchers often pause their jobs e.g. every 12-24 hours, and create checkpoints which capture all the data in memory. Using the checkpointing /snap storage, these checkpoints are many tens of times faster than without. For example, if a checkpoint for a 5 month simulation takes three hours on COSMA6, made every 12 hours, researchers will lose 1.8 million core hours (13% of available time) on a 4096 core job. On COSMA7, it will take only 10 minutes to create a checkpoint, and so only 0.2% of available time is lost.

COSMA6-8 network map (mixed InfiniBand fabric)