avoiding HOST_UNAVAILABLE exception: if there is not enough free memory does not spawn the VM at all.

instance state is set to "SHUTDOWN"

2 files changed, 19 insertions, 1 deletions

diff --git a/nova/virt/xenapi/vm_utils.py b/nova/virt/xenapi/vm_utils.py
index 4bbd522c1..3a0f0a149 100644
--- a/nova/virt/xenapi/vm_utils.py
+++ b/nova/virt/xenapi/vm_utils.py
@@ -139,6 +139,17 @@ class VMHelper(HelperBase):
         return vm_ref
 
     @classmethod
+    def ensure_free_mem(cls, session, instance):
+        instance_type = instance_types.INSTANCE_TYPES[instance.instance_type]
+        mem = str(long(instance_type['memory_mb']) * 1024 * 1024)
+        #get free memory from host
+        host = session.get_xenapi_host()
+        host_free_mem = session.get_xenapi().host.compute_free_memory(host)
+        if (host_free_mem < mem ):
+            return False
+        return True
+
+    @classmethod
     def create_vbd(cls, session, vm_ref, vdi_ref, userdevice, bootable):
         """Create a VBD record.  Returns a Deferred that gives the new
         VBD reference."""
diff --git a/nova/virt/xenapi/vmops.py b/nova/virt/xenapi/vmops.py
index e84ce20c4..2d4e53083 100644
--- a/nova/virt/xenapi/vmops.py
+++ b/nova/virt/xenapi/vmops.py
@@ -66,7 +66,14 @@ class VMOps(object):
         if vm is not None:
             raise exception.Duplicate(_('Attempted to create'
             ' non-unique name %s') % instance.name)
-
+        #ensure enough free memory, otherwise don't bother
+        if not VMHelper.ensure_free_mem(self._session,instance):
+                LOG.exception(_('instance %s: not enough free memory'),
+                              instance['name'])
+                db.instance_set_state(context.get_admin_context(),
+                                      instance['id'],
+                                      power_state.SHUTDOWN)
+                return 
         bridge = db.network_get_by_instance(context.get_admin_context(),
                                             instance['id'])['bridge']
         network_ref = \