Re: Can anyone boot a system using btrfs root with linux 3.14 or newer?

Calvin Walton
2014-04-23T20:25:44Z

On Wed, 2014-04-23 at 21:06 +0200, Kai Krakow wrote:
> Пламен Петров <plamen@petrovi.no-ip.info> schrieb:
>
> I'm going with the module suggestion from Marc, too.
>
> > /dev/sda2 / btrfs relatime,compress=zlib 0 0
>
> This line looks kinda useless to me. The compress=zlib option won't be
> applied at boot and cannot be changed at runtime because AFAIR btrfs does
> not allow that yet.

... My understanding is that the compress= option on btrfs *can* be
changed at run time. After remounting with a compress= option, later
writes will be done using the newly selected algorithm.

The compress= option is filesystem-wide, you cannot currently use
different compress= options for different subvolumes. Mounting a
subvolume with a different compress= option will change the compression
algorithm for all mounted subvolumes on that filesystem.

(Note that I wouldn't recommend zlib on most systems as a / filesystem -
it's slow to decompress compared to lzo, so it will cause slower boots
if your disk is reasonably fast.)

--
Calvin Walton <calvin.walton@kepstin.ca>