snippets/resource_accounting.md

+# 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 2019-03-01 |
+| Anselm                          | 0.65 |  2017-09-11 to 2019-03-01 |
+
+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.
+
+!!! note
+    **The allocations are requested/granted in normalized core-hours NCH.**
+
+!!! warning
+    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][1] 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][a].
+
+[1]: job-submission-and-execution.md
+
+[a]: https://pypi.python.org/pypi/it4i.portal.clients