diff --git a/openstack-ansible b/openstack-ansible
index 6ec9c83..7aff566 160000
--- a/openstack-ansible
+++ b/openstack-ansible
@@ -1 +1 @@
-Subproject commit 6ec9c83247cf91f828ca4e1b88f23b38713769b3
+Subproject commit 7aff566ddc9030e11655635ef24cc7917d4eabc2
diff --git a/openstack_deploy/user_variables.yml b/openstack_deploy/user_variables.yml
index dac964b..1a0cc97 100644
--- a/openstack_deploy/user_variables.yml
+++ b/openstack_deploy/user_variables.yml
@@ -42,7 +42,7 @@ nova_console_type: novnc
 # The intent is to allow flexible ratios (to a point) while using ram as the
 # bottom line limiting factor in determining a full host normally.
 nova_cpu_mode: host-passthrough
-nova_libvirt_disk_cachemodes: writeback
+nova_libvirt_disk_cachemodes: 'file=writeback'
 nova_compute_ksm_enabled: True
 nova_cpu_allocation_ratio: 10
 nova_disk_allocation_ratio: 5