Question: I have a 256GB SSD disk on which I converted my ext4 root FS to btrfs. I erased the ext4 backup subvolume, enabled compression and defragmented recursively to enable it on all files.
btrfs fi df / has an output that worries me though:
Data: total=148.00GB, used=106.11GBSystem: total=32.00MB, used=16.00KBMetadata: total=65.00GB, used=2.04GB
If I understand the output correctly, 65GB (1/4 of my disk!) is reserved for meta-data and not available for storing files. If this is correct, it would be a huge waste of my disk space. Am I understanding correctly? Can the metadata-allocated portion of my disk be resized?
Answer: First, make sure your kernel and the BTRFS user-space is up-to-date.
According to the BTRFS FAQ, you cannot resize the metadata block size. You can, however, try to run btrfs balance start -m
If that doesn’t work, you may have to backup your data and recreate the filesystem. (Take a look at this for more info.)