diff --git a/input/grid5000/disks.yaml b/input/grid5000/disks.yaml
index 995a79873e80a74f5fd55f2f727f08d8f4138578..99a068d3e4de40f9b915d49e362f53244a76d6e6 100644
--- a/input/grid5000/disks.yaml
+++ b/input/grid5000/disks.yaml
@@ -65,3 +65,5 @@ disk_vendor_model_mapping:
   Micron:
     - MTFDDAK480TDN
     - MTFDDAK960TDN
+  Unknown:
+    - unknown
diff --git a/lib/refrepo/input_loader.rb b/lib/refrepo/input_loader.rb
index ff94511b7d9b5aaa5ae8c0cd924b27c7705cd7b8..3025fea079eac68618871333467eaebaec26050e 100644
--- a/lib/refrepo/input_loader.rb
+++ b/lib/refrepo/input_loader.rb
@@ -183,6 +183,7 @@ end
 def add_kavlan_ipv6s(h)
   h['sites'].each_pair do |site_uid, hs|
     hs['clusters'].each_pair do |_cluster_uid, hc|
+      next if !hc['kavlan'] # skip clusters where kavlan is globally set to false (used for initial cluster installation)
       hc['nodes'].each_pair do |node_uid, hn|
         kvl_adapters = hn['network_adapters'].select { |_k,v| v['mountable'] and (v['kavlan'] or not v.has_key?('kavlan')) and v['interface'] == 'Ethernet' }
         if kvl_adapters.length > 0
@@ -222,6 +223,9 @@ def add_software(h)
   h['sites'].each_pair do |site_uid, hs|
     hs['clusters'].each_pair do |cluster_uid, hc|
       hc['nodes'].each_pair do |node_uid, hn|
+        if not hn.key?('software')
+          hn['software'] = {}
+        end
         hn['software']['postinstall-version'] = h['software']['postinstall-version']
         hn['software']['forced-deployment-timestamp'] = h['software']['forced-deployment-timestamp']
       end
diff --git a/lib/refrepo/valid/input/schemas/schema-node.yaml b/lib/refrepo/valid/input/schemas/schema-node.yaml
index 1342b88335a4731e1fc67d79726a7e9e4efd9717..8a44e1a33fe3cb216197e4570b227200c04e293a 100644
--- a/lib/refrepo/valid/input/schemas/schema-node.yaml
+++ b/lib/refrepo/valid/input/schemas/schema-node.yaml
@@ -23,11 +23,13 @@ chassis:
 exotic: optional_boolean
 gpu_devices: optional_hash
 kavlan:
-  <multi>:
-    <multi>: ip_address
+  <optional_hash>:
+    <multi>:
+      <multi>: ip_address
 kavlan6:
-  <multi>:
-    <multi>: ip_address
+  <optional_hash>:
+    <multi>:
+      <multi>: ip_address
 main_memory:
   ram_size: integer
   pmem_size: optional_integer