On Thu, Sep 09, 2010 at 12:43:28PM -0500, Anthony Liguori wrote: > Define "very large disks". > > My target for VM images is 100GB-1TB. Practically speaking, that at > least covers us for the next 5 years.
We have 2TB SATA disks shipping already, and people tend to produce more and more "data". I don't think adding such a limit these days is a good idea at all. It's fine to limit the (tested)implementation to around 100TB for now, but desining a new image format that doesn't reach into the petabyte range today is extremly short sightened. > I can only imagine the use case for qcow2-over-lvm is performance. But > the performance of QED on a file system is so much better than qcow2 > that you can safely just use a file system and avoid the complexity of > qcow2 over lvm. A volume manager has many advantages over an image format. For one it allows much larger extent allocation sizes, given you much less fragmentation. There's also lots of infrastructure for dealing with it. Last but not least using clustered lvm is much simpler than a clustered filesystem.
