On Wed, Dec 30, 2020 at 12:53 PM Ben Cotton <bcotton@xxxxxxxxxx> wrote: > > ** Update anaconda to perform the installation using <code>mount -o > compress=zstd:1</code> > ** Set the proper option in fstab (alternatively: set the XATTR) I think the most discoverable is using 'compress=zstd:1" as the mount option, and any one who wants to opt out would remove this. Upon removal, the system will become not compressed basically by attrition, as files are replaced. The mount option method is per file system. Since we have 'subvol' mount options to mount '/' and '/home' it seems plausible that compression is a per subvolume option, but it's not (see below). It's file system wide. The per subvolume, per directory, per file method of compression has some pretty esoteric nuances: - chattr +c method uses the default compression, currently this is zlib - btrfs property method can't be unset https://github.com/kdave/btrfs-progs/issues/308 - btrfs property compression 'none' is not the same as unsetting it, and it inherits just like any other xattr; none means mount option "compress" does not apply; mount option "compress-force" will compress files set with compression 'none'. - btrfs property method isn't recursive https://github.com/kdave/btrfs-progs/issues/278 - both methods stop at subvolume boundaries; i.e. if you set compression on a subvolume or directory, it inherits as you add new directories or files, but stops at a subvolume - compression flags survive through btrfs send/receive - this is particularly confusing because it can make it a bit difficult to have a copy without compression, and not immediately obvious that it's continuing to tag along This might best be turned into a flowchart :P > This Change only applies to newly installed systems. Existing systems > on upgrade will be unaffected, but can be converted manually with > <code>btrfs filesystem defrag -czstd -r</code>, updating `/etc/fstab` > and remounting. Note that defragmenting to compress is an option. You can just add the mount option to fstab and remount, but only new files will be compressed, but again by attrition, eventually most of the file system will end up compressed. -- Chris Murphy _______________________________________________ devel mailing list -- devel@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to devel-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@xxxxxxxxxxxxxxxxxxxxxxx
