diff --git a/beat/web/backend/migrations/0002_scheduler_addons.py b/beat/web/backend/migrations/0002_scheduler_addons.py
index 0150040f949ab078a7ebf18937439a058c41aea2..2b9c58fd220df15fd4e96b85ed53c26047adf189 100644
--- a/beat/web/backend/migrations/0002_scheduler_addons.py
+++ b/beat/web/backend/migrations/0002_scheduler_addons.py
@@ -58,6 +58,11 @@ class Migration(migrations.Migration):
             old_name='nb_cores_per_slot',
             new_name='cores_per_slot',
         ),
+        migrations.AlterField(
+            model_name='worker',
+            name='active',
+            field=models.BooleanField(default=False, help_text='If this worker is usable presently'),
+        ),
         migrations.RenameField(
             model_name='worker',
             old_name='nb_cores',
diff --git a/beat/web/backend/models.py b/beat/web/backend/models.py
index 63e54824241d2a53b7c141713a24e511bb27aaf6..73cefa8c688d868b84a85b224361507a43328ff5 100644
--- a/beat/web/backend/models.py
+++ b/beat/web/backend/models.py
@@ -50,10 +50,11 @@ from ..common.texts import Messages
 
 class EnvironmentManager(models.Manager):
 
-    def get_by_natural_key(self, name, version):
+    def get_by_natural_key(self, key):
+        name, version = key.split()
         return self.get(
                 name=name,
-                version=version,
+                version=version[1:-1],
                 )
 
 
@@ -114,18 +115,13 @@ class Environment(Shareable):
 
 
     def natural_key(self):
-        return (self.name, self.version)
+        return self.fullname()
 
 
     #_____ Utilities __________
 
     def fullname(self):
-        retval = '%s (%s)' % (
-            self.name,
-            self.version,
-            )
-        if not self.active: retval += ' [INACTIVE]'
-        return retval
+        return '%s (%s)' % (self.name, self.version)
 
     def get_absolute_url(self):
 
@@ -160,7 +156,7 @@ class Worker(models.Model):
 
     active = models.BooleanField(
         help_text=u'If this worker is usable presently',
-        default=True,
+        default=False,
         )
 
     cores = models.PositiveIntegerField()