Adding kvm-block-migration feature.

I wrote some description the below URL. I hope it may help for reviewing.
<http://etherpad.openstack.org/kvm-block-migration>

1 files changed, 9 insertions, 0 deletions

diff --git a/nova/exception.py b/nova/exception.py
index a5a25086e..3e2218863 100644
--- a/nova/exception.py
+++ b/nova/exception.py
@@ -273,6 +273,11 @@ class DestinationHypervisorTooOld(Invalid):
                 "has been provided.")
 
 
+class DestinationDiskExists(Invalid):
+    message = _("The supplied disk path (%(path)s) already exists, "
+                "it is expected not to exist.")
+
+
 class InvalidDevicePath(Invalid):
     message = _("The supplied device path (%(path)s) is invalid.")
 
@@ -699,6 +704,10 @@ class InstanceExists(Duplicate):
     message = _("Instance %(name)s already exists.")
 
 
+class InvalidSharedStorage(NovaException):
+    message = _("%(path)s is on shared storage: %(reason)s")
+
+
 class MigrationError(NovaException):
     message = _("Migration error") + ": %(reason)s"