Open Stack

Hi, I'd like you to take a look at this patch for potential
DocImpact.
https://review.openstack.org/18042

Log:
commit ccaf528463617f56c6347d042f51603c5426b3d1
Author: David McNally <dave.mcnally at hp.com>
Date:   Thu Dec 13 15:03:13 2012 +0000

    Adding ability to specify the libvirt cache mode for disk devices
    
    In past versions of Nova it was possible to explicitly configure
    the cache mode of disks via the libvirt XML template. The current approach
    makes this a derived setting of either “none” or “writethrough” based
    on the support of O_DIRECT. Whilst this provides a good set of default
    settings it removes the ability of the cloud provider to use other
    modes such as “writeback” and “unsafe” which are valuable in certain
    configurations.
    
    This change allows the cache mode to be specified on a per-disk type
    basis. If a disk type does not have a cache mode specified then the
    default behaviour remains unchanged.
    
    DocImpact
    
    bug 1086386
    
    Change-Id: I3d296fe0b4b9b976db02db90ad69fd299cd2096a