FAQ for BU renewal (#2624)

* FAQ for BU renewal * questions and answers * questions and answers * note that LUMI is unaffected * implement suggestions * typo * minor edits * added one i * minor edit --------- Co-authored-by: attesillanpaa <atte.sillanpaa@csc.fi>

Author: rkronberg

csc-overrides/partials/announcement.html

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 #}
 {# import ".icons/material/coffee.svg" as icon #}
 {# import ".icons/material/chat.svg" as icon #}
-{# import ".icons/material/information.svg" as icon #}
-{% import ".icons/material/alert.svg" as icon %}
+{% import ".icons/material/information.svg" as icon %}
+{# import ".icons/material/alert.svg" as icon #}
 {# import ".icons/material/wrench.svg" as icon #}
 {# import ".icons/material/rocket-launch.svg" as icon #}
 {# import ".icons/material/test-tube.svg" as icon #}
@@ -18,7 +18,7 @@
 <div class="announcement-icon">{{ icon }}</div>
 {# Put the announcement, in HTML, right under this comment! #}
 <p>
-Note: There will be a service break on Puhti on Tue Aug 12 from 8:30 to 12:00. <a href="https://research.csc.fi/service-break/puhti-service-break/">Click here for more info</a>.
+Note: There are upcoming changes to the billing unit model CSC uses in September 2025. <a href="{{ base_url | url }}/support/faq/bu-renewal/">Read the FAQ to learn more</a>.
 </p>
 {# ...and right above _this_ comment. #}
 <div class="announcement-icon announcement-icon-end">{{ icon }}</div>

docs/support/faq/bu-renewal.md

@@ -0,0 +1,79 @@
+# Questions and answers related to the billing unit renewal (2025)
+
+## 1. What are the new billing units?
+
+The new billing unit (BU) types are **HPC**, **HPC GPU**, **Cloud** and
+**Storage**. In other words, CSC's services for research will consume different
+billing units based on the kind of services used. A summary of which service
+uses which units is depicted below:
+
+* **HPC billing unit**
+ * Puhti, Mahti and Roihu jobs *without GPU*
+* **HPC GPU billing unit**
+ * Puhti, Mahti and Roihu jobs *with GPU*
+* **Cloud billing unit**
+ * cPouta, ePouta, Rahti, Pukki DBaaS, SD Desktop
+* **Storage billing unit**
+ * Puhti, Mahti and Roihu Lustre storage, Allas, Shared fileservice, SD
+ Connect
+
+!!! info "Note"
+ LUMI billing is **not** affected by the billing unit renewal.
+
+## 2. When are the new billing units taken into use?
+
+The new billing units will be taken into use in September 2025. The exact date
+will be announced later.
+
+## 3. Will I need to do something? What will happen to my old billing units?
+
+No, you do not need to anything. Old unused billing units already granted to
+projects will be migrated to the new units, i.e. no granted resources are lost.
+The mapping of old BUs to new BUs will be based on the past usage of the
+project. In other words, e.g. projects only running GPU jobs on Puhti will not
+get cloud billing units which they have no use for.
+
+You can check your current BU budget in [MyCSC](https://my.csc.fi), as well as
+using the `csc-projects` command on Puhti and Mahti.
+
+## 4. How will the BU renewal affect CSC's services?
+
+The migration to new billing units will have minimal effect on service usage
+and services will be available as usual. However, resource applications will be
+unavailable during the migration when old billing units are converted into new
+ones.
+
+## 5. How will the new billing units affect resource applications?
+
+Resource applications will be done in the four new billing units in the future.
+This means that users have to consider what kind of resources and services they
+need before applying for them.
+
+Moreover, the application limits for different resources will be separated
+based on the capacity available under every billing unit type. So far, all
+billing unit applications have been processed based on whether they are S-, M-,
+or L-sized applications. However, 1 million BUs used in cPouta has a much
+larger impact on the service capacity compared to the same amount of BUs used
+on Mahti CPU nodes. Thus, the size limits for resource applications will be
+based on the type of billing unit applied for.
+
+## 6. Will I lose billing units to the new BU cutter even if my projects use billing units?
+
+The billing unit renewal introduces a "cutter" that will depreciate unused BUs.
+The billing unit cutter only affects projects that have used **less than 40% of their
+billing units** in a 6 month period counted from the last billing unit grant
+or depreciation check. If a project has used more than that, no resources are
+cut. The billing unit cutter affects only academic projects with student
+projects being exempt.
+
+## 7. When will the first billing unit depreciation happen?
+
+The billing unit cutter is taken into use at the same time as the new units, so
+the first cuts would happen in **March 2026 at the earliest**. The billing unit
+usage of projects is checked six months after either the latest billing unit
+grant or the latest depreciation check.
+
+## More information
+
+* Blog: [Mapping out the future of billing units](https://csc.fi/en/blog/mapping-out-the-future-of-billing-unit/) (CSC.fi)
+* Blog: [Billing unit renewal schedule and changes](https://csc.fi/en/blog/billing-unit-renewal-schedules-and-changes/) (CSC.fi)

docs/support/faq/index.md

@@ -12,6 +12,7 @@
 * [Is there a glossary of the acronyms you keep using?](is-there-a-glossary-of-the-acronyms-you-keep-using.md)
 * [How to write good support requests to CSC Service Desk](../support-howto.md)
 * [My SSH keys do not work](ssh-keys-not-working.md)
+* [I have questions about the billing unit renewal (2025)](bu-renewal.md)
 
 ## Batch jobs
 * [Why does my batch job fail?](why-does-my-batch-job-fail.md)