manifesto7473 , 2 months ago

It is only for new data.

For example, you would have to defragment your filesystem again with btrfs filesystem defragment -r -v -czstd /. Where zstd is an algorithm and /, a root path. With this command, the default compression level will be used, which is level 3.

Be careful, defragmenting the btrfs file system will/can duplicate the data.

As for a mount point, if you decided to use zstd algorithm with level 1 compression, just add the compress=zstd:1 or compress-force=zstd:1 to the mount options (fstab or while mounting manually)