Latest revision as of 22:45, 9 February 2022

Silverblue and Kinoite will have /var on its own Btrfs subvolume

Summary

Silverblue and Kinoite: For new clean automatic (guided) installations, create a "var" subvolume to be mounted at /var.

Owner

Name: Chris Murphy
Email: bugzilla@colorremedies.com

Current status

Targeted release: Fedora Linux 36
Last updated: 2022-02-09
devel thread
FESCo issue: #2742
Tracker bug: #2051550
Release notes tracker: #803

Detailed Description

Currently, Silverblue and Kinoite mimic other Fedora desktops. There is a "root" subvolume mounted at / and a "home" subvolume mounted at /home.

This proposal adds a "var" subvolume to be mounted at /var.

The "var" subvolume will be located at the top-level of the Btrfs file system, along-side the "root" and "home" subvolumes. An entry in /etc/fstab will mount it at /var during startup.

Feedback

Benefit to Fedora

Users who opt into Btrfs features like snapshots and rollbacks.

By moving /var into its own subvolume, it can be independently snapshot and rolled back from the "root" subvolume, which contains /etc and /usr.
The ability to snapshot "var" and use Btrfs send/receive to replicate only "var" permits for an efficient way of backing up the variable system data, similar to snapshotting "home" and replicating it as a way of backing up user data.
- A clean install will restore the "root", therefore it doesn't strictly need to be backed up. Meanwhile "var" and "home" can be restored using snapshot replication via send/receive, or a favorite backup utility.

Scope

Proposal owners:
- change anaconda Silverblue and Kinoite profiles, such that automatic/guided installation creates a "var" subvolume mounted at /var.

Upgrade/compatibility impact

Change will not be applied to upgrades. But we can document steps to apply the change to existing installations.

How To Test

Do a clean installation and check df and /etc/fstab for an explicitly listed /var mount point.

User Experience

The change won't generally be noticeable to users
Users will see an additional /var mount point in /etc/fstab, and df
Some utilities, notably backup programs like borg backup, and rsync with -x option, will treat Btrfs subvolumes as separate file systems and may not descend (recursively) into them.

Dependencies

Anaconda

Contingency Plan

Contingency deadline: beta freeze (not a System Wide Change)
Blocks release? No

Documentation

No significant documentation is planned other than this change proposal.

N/A (not a System Wide Change)

Release Notes

@@ Line 15: / Line 15: @@
 == Current status ==
-[[Category:ChangePageIncomplete]]
+[[Category:ChangeAcceptedF36]]
 <!-- When your change proposal page is completed and ready for review and announcement -->
 <!-- remove Category:ChangePageIncomplete and change it to Category:ChangeReadyForWrangler -->
@@ Line 33: / Line 33: @@
 ON_QA -> change is fully code complete
 -->
-* FESCo issue: <will be assigned by the Wrangler>
+* [https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org/thread/FPSS64EWBODIRCBYP5WAZ56FMROUPOFX/ devel thread]
-* Tracker bug: <will be assigned by the Wrangler>
+* FESCo issue: [https://pagure.io/fesco/issue/2742 #2742]
-* Release notes tracker: <will be assigned by the Wrangler>
+* Tracker bug: [https://bugzilla.redhat.com/show_bug.cgi?id=2051550 #2051550]
+* Release notes tracker: [https://pagure.io/fedora-docs/release-notes/issue/803 #803]
 == Detailed Description ==
@@ Line 43: / Line 44: @@
 The "var" subvolume will be located at the top-level of the Btrfs file system, along-side the "root" and "home" subvolumes. An entry in `/etc/fstab` will mount it at `/var` during startup.
 == Feedback ==
 <!-- Summarize the feedback from the community and address why you chose not to accept proposed alternatives. This section is optional for all change proposals but is strongly suggested. Incorporating feedback here as it is raised gives FESCo a clearer view of your proposal and leaves a good record for the future. If you get no feedback, that is useful to note in this section as well. For innovative or possibly controversial ideas, consider collecting feedback before you file the change proposal. -->
 == Benefit to Fedora ==
@@ Line 51: / Line 54: @@
 Users who opt into Btrfs features like snapshots and rollbacks.
-* By moving /var into its own subvolume, it will be excluded from snapshots and rollbacks of the "root" subvolume, which contains `/etc` and `/usr`.
+* By moving /var into its own subvolume, it can be independently snapshot and rolled back from the "root" subvolume, which contains `/etc` and `/usr`.
-* Users will find it straightforward to rollback "root" while not rolling back "var": including logs, VMs, databases, and so on.
+* The ability to snapshot "var" and use Btrfs send/receive to replicate only "var" permits for an efficient way of backing up the variable system data, similar to snapshotting "home" and replicating it as a way of backing up user data.
-* The ability to snapshot only "var" and use Btrfs send/receive to replicate only "var" permits for an efficient way of backing up the variable system data.
+** A clean install will restore the "root", therefore it doesn't strictly need to be backed up. Meanwhile "var" and "home" can be restored using snapshot replication via send/receive, or a favorite backup utility.
-** A clean install can restore the "root", therefore it doesn't strictly need to be backed up. Meanwhile "var" and "home" can be restored using snapshot replication via send/receive.
 == Scope ==
 * Proposal owners:
-** changes to lorax and anaconda as needed so that Silverblue and Kinoite variants have their own installation kickstart, such that automatic/guided installation automatically creates "var".
+** change anaconda Silverblue and Kinoite profiles, such that automatic/guided installation creates a "var" subvolume mounted at /var.
-*** possible liability, determine whether the the addition of /var mount point for Btrfs scheme results in /var mount point for other schemes (and inhibit)
-* Other developers: <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
-<!-- What work do other developers have to accomplish to complete the feature in time for release?  Is it a large change affecting many parts of the distribution or is it a very isolated change? What are those changes?-->
-* Release engineering: [https://pagure.io/releng/issues #Releng issue number] <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
-<!-- Does this feature require coordination with release engineering (e.g. changes to installer image generation or update package delivery)?  Is a mass rebuild required?  include a link to the releng issue.
-The issue is required to be filed prior to feature submission, to ensure that someone is on board to do any process development work and testing and that all changes make it into the pipeline; a bullet point in a change is not sufficient communication -->
-* Policies and guidelines: N/A (not needed for this Change) <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
-<!-- Do the packaging guidelines or other documents need to be updated for this feature?  If so, does it need to happen before or after the implementation is done?  If a FPC ticket exists, add a link here. Please submit a pull request with the proposed changes before submitting your Change proposal. -->
-* Trademark approval: N/A (not needed for this Change)
-<!-- If your Change may require trademark approval (for example, if it is a new Spin), file a ticket ( https://pagure.io/Fedora-Council/tickets/issues ) requesting trademark approval from the Fedora Council. This approval will be done via the Council's consensus-based process. -->
-* Alignment with Objectives:
-<!-- Does your proposal align with the current Fedora Objectives: https://docs.fedoraproject.org/en-US/project/objectives/ ? It's okay if it doesn't, but it's something to consider -->
 == Upgrade/compatibility impact ==
@@ Line 87: / Line 73: @@
 == How To Test ==
-<!-- This does not need to be a full-fledged document. Describe the dimensions of tests that this change implementation is expected to pass when it is done.  If it needs to be tested with different hardware or software configurations, indicate them.  The more specific you can be, the better the community testing can be.
-Remember that you are writing this how to for interested testers to use to check out your change implementation - documenting what you do for testing is OK, but it's much better to document what *I* can do to test your change.
-A good "how to test" should answer these four questions:
-. What special hardware / data / etc. is needed (if any)?
-. How do I prepare my system to test this change? What packages
-need to be installed, config files edited, etc.?
-. What specific actions do I perform to check that the change is
-working like it's supposed to?
-. What are the expected results of those actions?
--->
 * Do a clean installation and check `df` and `/etc/fstab` for an explicitly listed `/var` mount point.
-<!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
 == User Experience ==
-<!-- If this change proposal is noticeable by users, how will their experiences change as a result?
- This section partially overlaps with the Benefit to Fedora section above. This section should be primarily about the User Experience, written in a way that does not assume deep technical knowledge. More detailed technical description should be left for the Benefit to Fedora section.
- Describe what Users will see or notice, for example:
-  - Packages are compressed more efficiently, making downloads and upgrades faster by 10%.
-  - Kerberos tickets can be renewed automatically. Users will now have to authenticate less and become more productive. Credential management improvements mean a user can start their work day with a single sign on and not have to pause for reauthentication during their entire day.
- - Libreoffice is one of the most commonly installed applications on Fedora and it is now available by default to help users "hit the ground running".
- - Green has been scientifically proven to be the most relaxing color. The move to a default background color of green with green text will result in Fedora users being the most relaxed users of any operating system.
--->
 * The change won't generally be noticeable to users
@@ Line 124: / Line 85: @@
 == Dependencies ==
-<!-- What other packages (RPMs) depend on this package?  Are there changes outside the developers' control on which completion of this change depends?  In other words, completion of another change owned by someone else and might cause you to not be able to finish on time or that you would need to coordinate?  Other upstream projects like the kernel (if this is not a kernel change)? -->
-<!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
-* Anaconda/blivet, lorax, and possibly kickstarts
+* Anaconda
 == Contingency Plan ==
-<!-- If you cannot complete your feature by the final development freeze, what is the backup plan?  This might be as simple as "Revert the shipped configuration".  Or it might not (e.g. rebuilding a number of dependent packages).  If you feature is not completed in time we want to assure others that other parts of Fedora will not be in jeopardy.  -->
-* Contingency mechanism: (What to do?  Who will do it?) N/A (not a System Wide Change)  <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
-<!-- When is the last time the contingency mechanism can be put in place?  This will typically be the beta freeze. -->
 * Contingency deadline: beta freeze (not a System Wide Change)  <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
 <!-- Does finishing this feature block the release, or can we ship with the feature in incomplete state? -->
@@ Line 142: / Line 97: @@
 == Documentation ==
-<!-- Is there upstream documentation on this change, or notes you have written yourself?  Link to that material here so other interested developers can get involved. -->
 No significant documentation is planned other than this change proposal.

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