Re: cloning single-device btrfs file system onto multi-device one

[Stephane Chazelas <stephane.chazelas@gmail.com>]

2011-03-28 14:24:03 +0100, Stephane Chazelas:
> 2011-03-23 12:13:45 +0700, Fajar A. Nugraha:
> > On Mon, Mar 21, 2011 at 11:24 PM, Stephane Chazelas
> > <stephane.chazelas@gmail.com> wrote:
> > > AFAICT, compression is enabled at mount time and would
> > > only apply to newly created files. Is there a way to compress
> > > files already in a btrfs filesystem?
> > 
> > You need to select the files manually (not possible to select a
> > directory), but yes, it's possible using "btrfs filesystem defragment
> > -c"
> [...]
> 
> Thanks. However I find that for files that have snapshots, it
> ends up increasing disk usage instead of reducing it (size of
> the file + size of the compressed file, instead of size of the
> file).
> 
> If I do the btrfs fi de on both the volume and its snapshot, I
> end up with some benefit only if the compression ratio is over
> 2 (and with more snapshots, there's little chance of getting any
> benefit at all). Also, with dozens of snapshots on a 4TB volume,
> it's likely to take weeks to do.
> 
> Is there a way around that?
[...]

OK, sorry. I can see now that it's a FAQ. So the answer to my
question would be "no"...

-- 
Stephane