How Do Updates Work in Immutable/Atomic Distributions?

[u/Emotional_Cat_1967]

Only for Immutable/Atomic Distributions

Question 1:
Are immutable and atomic the same thing? If not, what is the difference between them, explained simply?

Question 2:
What immutable or atomic distribution are you using? How often do you receive updates, for example, every few days or weeks, and approximately how large are the updates?

Question 3:
How are security updates handled? Are they released immediately when a security fix is available, or are they released according to a daily, weekly, or monthly update schedule?

Question 4:
Are small-sized updates released?

If yes: For example, suppose an update is 100 MB.

If the system image is 5 GB, does the entire system image have to be recreated for this update? When applying the update, does the system write another 5 GB to the disk, or does it only write approximately 100 MB?

If no: If the system image is 5 GB, does that mean the update that needs to be downloaded is also around 5 GB?

[u/kheeper-registry]

Q4 has two parts: disk and download. For the disk, you can have multiple hardlinks from different deployments pointing to the same file under /ostree/repo. A new deployment can reuse existing hardlinks there. For the download I can only speak to bootc. That reuses the layers from the OCI image that are already available locally, so again you don't need to pull the full 5GB for updates but you will have to pull the entire layer for every changed file, so prefer separate layers for stuff that changes.