diff --git a/planetstack/core/models/sliver.py b/planetstack/core/models/sliver.py
index 580c2af..8ebcbd4 100644
--- a/planetstack/core/models/sliver.py
+++ b/planetstack/core/models/sliver.py
@@ -8,10 +8,11 @@
 from core.models import Node
 from core.models import Site
 from core.models import DeploymentNetwork
+from openstack.manager import OpenStackManager
 
 # Create your models here.
 class Sliver(PlCoreBase):
-    instance_id = models.CharField(max_length=200, help_text="Nova instance id")    
+    instance_id = models.CharField(null=True, blank=True, max_length=200, help_text="Nova instance id")    
     name = models.CharField(max_length=200, help_text="Sliver name")
     instance_name = models.CharField(blank=True, null=True, max_length=200, help_text="OpenStack generated name")
     ip = models.GenericIPAddressField(help_text="Sliver ip address", blank=True, null=True)
@@ -20,18 +21,21 @@
     slice = models.ForeignKey(Slice, related_name='slivers')
     node = models.ForeignKey(Node, related_name='slivers')
     deploymentNetwork = models.ForeignKey(DeploymentNetwork, verbose_name='deployment', related_name='sliver_deploymentNetwork')
-    numberCores = models.IntegerField(verbose_name="Number of Cores", help_text="Number of cores for sliver", default=2)
+    numberCores = models.IntegerField(verbose_name="Number of Cores", help_text="Number of cores for sliver", default=0)
 
 
     def __unicode__(self):  return u'%s' % (self.instance_name)
 
     def save(self, *args, **kwds):
-        if not self.slice.subnet.exists():
-            raise exceptions.ValidationError, "Slice %s has no subnet" % self.slice.name
-
-        self.os_manager.save_sliver(self)
+        if not self.name:
+            self.name = self.slice.name
+        if not hasattr(self, 'os_manager'):
+            setattr(self, 'os_manager', OpenStackManager())
+            self.os_manager.save_sliver(self)
         super(Sliver, self).save(*args, **kwds)
 
     def delete(self, *args, **kwds):
-        self.os_manager.delete_sliver(self)
+        if not hasattr(self, 'os_manager'):
+            setattr(self, 'os_manager', OpenStackManager())
+            self.os_manager.delete_sliver(self)
         super(Sliver, self).delete(*args, **kwds)