Fedora Btrfs Activity Continues - New Options To Control Discard, Compression
A new Anaconda Kickstart install configuration knob is being added for setting the async discard behavior for solid-state drives. This configuration option will simply set the Btrfs DISCARD option to be enabled by default per the /etc/fstab options. They are still weighing whether to make it the default or more than likely that default transition would be next year for Fedora 34.
Of Btrfs DISCARD reliability they note, "Facebook has been using it in production for [more than] 6 months, it's solved many problems with no regressions. Fedora already enables weekly fstrim via fstrim.timer by default. The advantage of 'discard=async' is mainly for workloads with heavy writes and deletes. Once per week fstrim might not be frequent enough. Both fstrim and discard=async mount option can peacefully co-exist."
Another option/enhancement they are looking at is enabling compression for Btrfs installs. At the moment they are looking at using Zstd with the basic compression level of 1. Btrfs compression can still be tuned (or disabled) on a per-subvolume/directory/file basis. Fedora 33 defaults still to be decided.
Additionally the Fedora developers continue working on improving the documentation around Btrfs support for their distribution. Fedora ARM hard-float desktop image builds have also been fixed up with Btrfs working by default.
More details on the Fedora 33 Btrfs quest via this latest report.