On 09/09/2010 11:48 AM, Paolo Bonzini wrote:
On 09/09/2010 02:49 PM, Anthony Liguori wrote:
We should optimize for the future. That means a btrfs file system and/or
enterprise storage.
So we should just implement a copy-on-read wrapper that generates a
sparse raw image and uses FIEMAP (or whatever it is called these days)
to test for the presence of extents. Then you let btrfs handle
everything else...
My position is that we'll need a sparse image format well into the
future because while btrfs may be ubiquitous as a file system, IRL,
people transfer images around all of the time through dumb transports
like HTTP and fat-formatted USB keys. A 100GB image with 1GB allocated
cannot explode to 100GB just because HTTP is a dump transport.
Where we should do copy-on-read is a different topic. Really, I should
have waited to share that feature to avoid confusing the current discussion.
Regards,
Anthony Liguori
Paolo
