Add note about metadata/ephemeral volumes (#2795)

* Add note about metadata/ephemeral volumes

* Add note to what's new about new ephemeral disks partition

* fix typo

---------

Co-authored-by: Antonio Delgado <adelgado@csc.fi>

Author: ajdelgado

docs/cloud/pouta/images.md

@@ -4,15 +4,15 @@
 
 CSC provides a set of standard images that are well suited for cloud
 use. In most cases, you can use these images instead of creating your
-own. The images are created automatically using _diskimage-builder_. 
+own. The images are created automatically using _diskimage-builder_.
 If you are interested in the details of how
 these images are created, see this [GitHub page]. The images are
 updated at regular intervals so that they contain the latest security
 updates at the time virtual machines are launched.
 
 It is possible that for some use cases the automatically created
 images are not suitable. In this case, it is possible to create your
-own images and use them instead. However, there are some caveats 
+own images and use them instead. However, there are some caveats
 to consider when creating your own images that you would not
 need to consider when using the default images. For more information,,
 see [Advanced images](adding-images.md)
@@ -82,6 +82,12 @@ This can be useful for doing tests in Pouta, such as testing if the network work
 how fast you can launch an instance. You should not use this for persistent
 VMs, and you should always delete the instance when you are done with
 testing. There is very little reason for end-users using this image, and if
-you are unsure, CentOS and Ubuntu are better choices 99% of the time. 
+you are unsure, CentOS and Ubuntu are better choices 99% of the time.
 
 [GitHub page]: https://github.com/CSC-IT-Center-for-Science/diskimage-builder-csc-automation
+
+## Image metadata
+Images updated since November of 2025 might have metadata reporting the type and version of
+the operating system (os_type, os_distro). That information allow OpenStack to create
+[ephemeral](ephemeral-storage.md) disks with the more appropriate format ext4 instead of vfat. Be
+aware that this might affect your workflow or automations.

docs/support/wn/cloud-new.md

@@ -1,5 +1,10 @@
 # Cloud services
 
+## Small changes in Pouta's cloud images creation, 2.12.2025
+
+Since end of November of 2025, newly created Public images in Pouta will create the ephemeral partitions as ext4 instead of vfat. This won't be
+an issue for most people but in some cases, you might expect a certain file system format.
+
 ## New database minor versions available in Pukki, 25.11.2025
 
 PostgreSQL 17.7 and 14.20 and MariaDB 11.4.8 are now available in Pukki DBaaS. See [PostgreSQL's](https://www.postgresql.org/about/news/postgresql-181-177-1611-1515-1420-and-1323-released-3171/) and [MariaDB's](https://mariadb.com/docs/release-notes/community-server/11.4/11.4.8) documentation for release notes.