On 2015-08-18 11:10, Timothy Normand Miller wrote:
> I ran the following command.  It spent a lot of time creating a
> 1672450048 byte file.  Then it stopped writing to the file and started
> using 100% CPU.  It's currently doing no I/O, and it's been doing that
> for a while now.  Is that supposed to happen?
>
Not normally, I've seen this happen sometimes before for a short period 
when it hits a group of blocks that don't compress well, but that 
usually goes away after a few seconds.  I think this is probably a bug. 
  However, it isn't unusual for a big filesystem to have a really small 
image produced if it contains mostly big files (btrfs-image just copies 
the metadata, not the actual file data, so even without compression, it 
usually will take up less space than the filesystem being imaged).