https://fedoraproject.org/wiki/Changes/FedoraCloudBtrfsByDefault
== Summary ==
For cloud installs of Fedora, we want to provide advanced file system
features to users in a transparent fashion. Thus, we are changing the
file system for the Cloud Edition to Btrfs so we can leverage its
features and capabilities to improve the quality of experience for
Cloud users.
== Owners ==
* Name: [[User:Davdunc|David Duncan]], [[User:Chrismurphy|Chris
Murphy]], [[User:Josef|Josef Bacik]], [[User:Salimma|Michel Alexandre
Salim]], [[User:Dcavalca|Davide Cavalca]], [[User:Ngompa|Neal Gompa]],
[[User:Dustymabe|Dusty Mabe]], [[User:Malmond|Matthew Almond]]
* Email: davd...@amazon.com, chrismur...@fedoraproject.org,
jo...@toxicpanda.com, mic...@michel-slm.name, dcava...@fb.com,
ngomp...@gmail.com, du...@dustymabe.com, malm...@fb.com
* Products: Fedora Cloud Edition
* Responsible WGs: Fedora Cloud WG
== Detailed Description ==
Fedora Cloud Edition will switch to using Btrfs for its images. The
configuration for the Cloud Edition will match the setup used on the
desktop variants, as this has been very well-tested with production
deployments across multiple Fedora Linux releases now.
This includes the same subvolume layout that is used on the desktop
variants [[Changes/BtrfsByDefault|as introduced in Fedora Linux 33]],
as well as transparent Zstd compression
[[Changes/BtrfsTransparentCompression|as introduced in Fedora Linux
34]].
== Feedback ==
== Benefit to Fedora ==
The benefits are similar to
[[Changes/BtrfsByDefault#Benefit_to_Fedora|the ones for Fedora desktop
variants]]; however, there are specific benefits for Fedora Cloud:
* Adds support to Fedora Cloud for [[Changes/RPMCoW|the Change to
introduce support for Copy-on-Write enhancements to improve
performance to package management]]
* Adds the ability to logically separate contents of the volume
without dividing up the available space
** Transparent compression: significantly reduces write amplification
and improves effective I/O throughput
** Reflinks and snapshots improve efficiency for use cases like
containers (CRI-O, containerd, and Podman support both)
* Storage devices can be flaky, resulting in data corruption; Btrfs
can help mitigate this
** Everything is checksummed and verified on every read
** Corrupt data results in EIO (input/output error), instead of
resulting in application confusion, and isn’t replicated into backups
and archives
* Improves system responsiveness under pressure
** Btrfs has been tested in production to have proper IO isolation
capability via cgroups2
** Completes the resource control picture: memory, cpu, IO isolation
* File system resize
** Online shrink and grow are cornerstones of the Btrfs design
* Complex storage setups are… complicated
** Simple and comprehensive command interface. One master command
** Simpler to boot, all code is in the kernel, no initramfs complexities
** Simple and efficient file system replication, including incremental
backups, with btrfs send and btrfs receive
== Scope ==
* Proposal owners:
** Submit PRs for Cloud Edition kickstarts to produce disk images using Btrfs.
* Release engineering: [https://pagure.io/releng/issue/10129 #10129]
* Policies and guidelines: N/A
* Trademark approval: N/A
== Upgrade/compatibility impact ==
Change will not affect upgrades.
== How To Test ==
Once the change lands in Rawhide, spin up the images in AWS, GCP, and
KVM/OpenStack to test to see systems boot and run.
== User Experience ==
* Mostly transparent.
* Space savings and extend hardware life, via compression.
* Utilities for used and free space are expected to behave the same.
No special commands are required.
* More detailed information can be revealed by btrfs
specific commands.
* cp command will create reflink copies
[https://src.fedoraproject.org/rpms/coreutils/c/5d08d14b/ by default.]
== Dependencies ==
None.
== Contingency Plan ==
* Contingency mechanism: Owner will revert changes back to the
previous ext4 configuration
* Contingency deadline: Beta freeze
* Blocks release? Yes
* Blocks product? Cloud
== Documentation ==
Strictly speaking, no extra documentation is required reading for users.
== Release Notes ==
The default file system on the cloud is now Btrfs, following the
desktop change in Fedora Linux 33. Fedora Server, IoT, and CoreOS are
still specifically excluded.
--
Ben Cotton
He / Him / His
Fedora Program Manager
Red Hat
TZ=America/Indiana/Indianapolis
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