Images could be more optimised for better performance

[Robie Basak]

15:43 <hallyn> rbasak: say, in uvtool, have youconsidered tuning the backing store files?
15:44 <hallyn> i.e. preallocation=metadata,compat=1.1,lazy_refcounts=on is supposed to be a nice speed increase
...
15:46 <hallyn> well, precise couldn't do compat=1.1 i guess, only 1.0

So when we sync images, it sounds like if the release supports the newer format, we should optimise the images on download and before import. Either by default with an option to disable, or with an option to enable.

[Robie Basak (racb)]

15:50 <hallyn> btw http://sevennet.org/2015/01/08/how-to-incredibly-slow-kvm-disk-performance-qcow2-disk-files-virtio-programming-dev-development/ was one example reference