Open Stack

Hi, I'd like you to take a look at this patch for potential
DocImpact.
https://review.openstack.org/20545

Log:
commit 46de2d1e2d0abd6fdcd4da13facaf3225c721f5e
Author: Rafi Khardalian <rafi at metacloud.com>
Date:   Sat Jan 26 09:02:19 2013 +0000

    Libvirt: Add support for live snapshots
    
    blueprint libvirt-live-snapshots
    
    Implements support for live snapshots when QEMU 1.3 and Libvirt
    1.0.0 are available. This implementation may function with other
    hypervisors, at which point _check_use_live_snapshots can be
    adjusted accordingly.
    
    At a high level, the process is as follows. First we create a
    destination file for the snapshot. This file uses the same backing
    file as the origin disk and is of the same virtual size. We do this
    since the combination of blockRebase and "shallow" copies are the
    only bug-free method available as of QEMU 1.3 (Vish has submitted
    patches upstream). This process ultimately produces a CoW file,
    representing only the current delta between the root disk and
    backing file. The final step converts the CoW delta to a backless
    image matching the format of the origin disk.
    
    Flags: DocImpact
    Change-Id: Icba53336556295722c3f8b7345e6cd09d8ccfed9