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Resource Accounting Policy

Starting with the 24th open access grant competition, the accounting policy has been changed from normalized core hours (NCH) to node-hours. This means that it is now required to apply for node hours of the specific cluster and node type:

  1. Barbora CPU
  2. Barbora GPU
  3. Barbora FAT
  4. DGX-2
  5. Karolina CPU
  6. Karolina GPU
  7. Karolina FAT

The accounting runs whenever the nodes are allocated via the Slurm workload manager (the sbatch, salloc command), regardless of whether the nodes are actually used for any calculation. The same rule applies for unspent reservations.

Conversion Table

Resources Conversion for 1 node-hour
Barbora CPU 36 core-hours
Barbora GPU 4 GPU hours
Barbora FAT 128 core-hours
DGX-2 16 GPU hours
Karolina CPU 128 core-hours
Karolina GPU 8 GPU hours
Karolina FAT 768 core-hours

Original Resource Accounting Policy

The original policy, as stated below, is still applied to projects from previous grant competitions.

Wall-Clock Core-Hours WCH

The wall-clock core-hours (WCH) are the basic metric of computer utilization time. 1 wall-clock core-hour is defined as 1 processor core allocated for 1 hour of wall-clock time. For example, allocating a full node (i.e. 36 cores) on Barbora for 1 hour amounts to 36 wall-clock core-hours.

Normalized Core-Hours NCH

The resources subject to accounting are the normalized core-hours (NCH). The normalized core-hours are obtained from WCH by applying a normalization factor:


All jobs are accounted in normalized core-hours, using factor F valid at the time of the execution:

System F
Karolina 1.00
Barbora CPU 1.40
Barbora GPU 4.50
DGX-2 5.50

Factors are valid as of July 9, 2022.

The normalized core-hours were introduced to treat systems of different age on equal footing. Normalized core-hour is an accounting tool to discount the legacy systems.

See examples in the Job submission and execution section.

Consumed Resources

Check how many core-hours have been consumed. The command it4ifree is available on cluster login nodes.

$ it4ifree

Projects I am participating in
PID         Days left      Total    Used WCHs    Used NCHs    WCHs by me    NCHs by me     Free
----------  -----------  -------  -----------  -----------  ------------  ------------  -------
OPEN-XX-XX  323                0      5169947      5169947         50001         50001  1292555

Projects I am Primarily Investigating
PID        Login         Used WCHs    Used NCHs
---------- ----------  -----------  -----------
OPEN-XX-XX user1            376670       376670
           user2           4793277      4793277

WCH   =    Wall-clock Core Hour
NCH   =    Normalized Core Hour

The it4ifree command is a part of the it4i.portal.clients package, located here.