Optimize Nova disk_cachemodes and hw_disk_discard options for RBD

When using the Nova RBD driver for the ephemeral storage it is
suggested by the Ceph RBD OpenStack guide [1] to optimize certain
settings; this change will set disk_cachemodes and hw_disk_discard
accordingly to the guide.

1. http://docs.ceph.com/docs/master/rbd/rbd-openstack/

Change-Id: I8d2ee89ca4ff5458d1888cc037e2e91d19025ad4

diff --git a/puppet/manifests/overcloud_compute.pp b/puppet/manifests/overcloud_compute.pp
index cc58cb1..43e8778 100644 (file)
--- a/puppet/manifests/overcloud_compute.pp
+++ b/puppet/manifests/overcloud_compute.pp
@@ -90,8 +90,17 @@ if str2bool(hiera('nova::use_ipv6', false)) {
 } else {
   $vncserver_listen = '0.0.0.0'
 }
-class { '::nova::compute::libvirt' :
-  vncserver_listen => $vncserver_listen,
+
+if $rbd_ephemeral_storage {
+  class { '::nova::compute::libvirt':
+    libvirt_disk_cachemodes => ['network=writeback'],
+    libvirt_hw_disk_discard => 'unmap',
+    vncserver_listen        => $vncserver_listen,
+  }
+} else {
+  class { '::nova::compute::libvirt' :
+    vncserver_listen => $vncserver_listen,
+  }
 }
 
 nova_config {