Open Stack

Hi, I'd like you to take a look at this patch for potential
DocImpact.
https://review.openstack.org/33333

Log:
commit 78ed7b0a8e558c40056f23551e56cdb03fca9fa4
Author: Samuel Merritt <sam at swiftstack.com>
Date:   Thu Jun 13 11:24:29 2013 -0700

    Local write affinity for object PUT requests.
    
    The proxy can now be configured to prefer local object servers for PUT
    requests, where "local" is governed by the "write_affinity". The
    "write_affinity_node_count" setting controls how many local object
    servers to try before giving up and going on to remote ones.
    
    I chose to simply re-order the object servers instead of filtering out
    nonlocal ones so that, if all of the local ones are down, clients can
    still get successful responses (just slower).
    
    The goal is to trade availability for throughput. By writing to local
    object servers across fast LAN links, clients get better throughput
    than if the object servers were far away over slow WAN links. The
    downside, of course, is that data availability (not durability) may
    suffer when drives fail.
    
    The default configuration has no write affinity in it, so the default
    behavior is unchanged.
    
    Added some words about these settings to the admin guide.
    
    DocImpact
    
    Change-Id: I09a0bd00524544ff627a3bccdcdc48f40720a86e

Automatically generated bug (please review):
https://bugs.launchpad.net/bugs/1192657