docs: Document tmpfs-backed storage for usr-overlay - #2381
Open
jmarrero wants to merge 1 commit into
Open
Conversation
The transient overlay created by `bootc usr-overlay` is backed by a tmpfs filesystem, meaning installed packages consume system RAM rather than persistent disk. The kernel default sizes this tmpfs at 50% of physical RAM, and there is currently no pre-flight space check before the overlay fills up. This is not obvious from the existing documentation and can lead to confusing ENOSPC errors on memory-constrained systems such as CI runners or small VMs, where users may assume the overlay uses disk storage. Assisted-by: AI Signed-off-by: Joseph Marrero Corchado <jmarrero@redhat.com>
jmarrero
force-pushed
the
docs/usr-overlay-tmpfs-storage
branch
from
August 14, 2026 02:45
89ac779 to
732e645
Compare
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
The transient overlay created by
bootc usr-overlayis backed by atmpfs filesystem, meaning installed packages consume system RAM rather
than persistent disk. The kernel default sizes this tmpfs at 50% of
physical RAM, and there is currently no pre-flight space check before
the overlay fills up.
This is not obvious from the existing documentation and can lead to
confusing ENOSPC errors on memory-constrained systems such as CI
runners or small VMs, where users may assume the overlay uses disk
storage.
Assisted-by: AI
I am knowledgeable in this problem domain and reviewed the change carefully.