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## Resource Accounting Policy

### 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. Allocating a full node (16 cores Anselm,  24 cores Salomon)
for 1 hour amounts to 16 wall-clock core-hours (Anselm) or 24 wall-clock core-hours (Salomon).
### 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:
NCH = F*WCH
All jobs are accounted in normalized core-hours, using factor F valid at the time of the execution:

| System                          | F   | Validity |
| ------------------------------- | -   | -------- |
| Salomon                         | 1.00 |  2017-09-11 to 2018-06-01 |
| Anselm                          | 0.65 |  2017-09-11 to 2018-06-01 |

The accounting runs whenever the computational cores are allocated via the PBS Pro workload manager (the qsub command), regardless of whether
the cores are actually used for any calculation. 
    *The allocations are requested/granted in normalized core-hours NCH.
    
Whenever the term core-hour is used in this documentation, we mean the normalized core-hour, NCH.
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. The past (before 2017-09-11) F factors are all 1.0.
In future, the factors F will be updated, as new systems are installed. Factors F are expected to only decrease in time.

See examples in the [Job submission and execution](job-submission-and-execution/) section.

### Consumed Resources

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

```console
$ 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

Legend
======
WCH   =    Wall-clock Core Hour
NCH   =    Normalized Core Hour
```
The **it4ifree** command is a part of it4i.portal.clients package, located here: <https://pypi.python.org/pypi/it4i.portal.clients>