Arch Linux

860lacov

Member

Registered: 2020-05-02

Posts: 497

Need a little help with new default btrfs-progs options

I use btrfs on my laptop.

I created partition some time ago (before kernel 5.15)

Today when I wanted to format pen drive with btrfs (it was for test purposes) I got a message:

NOTE: several default settings have changed in version 5.15, please make sure
      this does not affect your deployments:
      - DUP for metadata (-m dup)
      - enabled no-holes (-O no-holes)
      - enabled free-space-tree (-R free-space-tree)

I know what DUP is, and I did set this parameter during my partition setup.

Few minutes ago, I read that free-space-tree is just space_cache=v2 option. It is good for very large drives. I created my partition on older kernel, so I assume that my space_cache version i v1 right now. I have 1 TB drive, so is there any good reason to convert version to v2?

And about no-holes
man says:

no-holes
           (default since btrfs-progs 5.15, kernel support since 3.14)

           improved representation of file extents where holes are not explicitly stored as an extent, saves a few
           percent of metadata if sparse files are used

I understand what this mean in my language but even in my language I don't understand what does it mean

Could you please explain me this in a simpler way if there is any?
Is it possible to enable this future on already created filesystem?