diff --git a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-1.json b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-1.json
index 4975294c3430a2414b4cb72b0020b07a2820dc19..320278181752a0949d7cf61dd5bc9de7fba4b508 100644
--- a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-1.json
+++ b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-1.json
@@ -2,7 +2,7 @@
   "architecture": {
     "platform_type": "x86_64",
     "smp_size": 2,
-    "smt_size": 4
+    "smt_size": 8
   },
   "bios": {
     "release_date": "08/10/2007",
@@ -90,7 +90,7 @@
   "supported_job_types": {
     "besteffort": true,
     "deploy": true,
-    "virtual": null
+    "virtual": "ivt"
   },
   "type": "node",
   "uid": "granduc-1"
diff --git a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-10.json b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-10.json
index f3154d153aaddc9a57116db3dafa5a67e36a7e29..86df72b7ddd77b1297197082f10b8f8ed94dd5cd 100644
--- a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-10.json
+++ b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-10.json
@@ -2,7 +2,7 @@
   "architecture": {
     "platform_type": "x86_64",
     "smp_size": 2,
-    "smt_size": 4
+    "smt_size": 8
   },
   "bios": {
     "release_date": "08/10/2007",
@@ -90,7 +90,7 @@
   "supported_job_types": {
     "besteffort": true,
     "deploy": true,
-    "virtual": null
+    "virtual": "ivt"
   },
   "type": "node",
   "uid": "granduc-10"
diff --git a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-11.json b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-11.json
index 3368232196a64c7394c8535c5fb635669c69551f..dfbe817d8b30d47a0804f1b965d28e09f26d20fe 100644
--- a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-11.json
+++ b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-11.json
@@ -2,7 +2,7 @@
   "architecture": {
     "platform_type": "x86_64",
     "smp_size": 2,
-    "smt_size": 4
+    "smt_size": 8
   },
   "bios": {
     "release_date": "08/10/2007",
@@ -90,7 +90,7 @@
   "supported_job_types": {
     "besteffort": true,
     "deploy": true,
-    "virtual": null
+    "virtual": "ivt"
   },
   "type": "node",
   "uid": "granduc-11"
diff --git a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-12.json b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-12.json
index 7c5fbeea62bb058e3e5933b9d1c02739eb63c17e..ea61cd27a5ef404eea58fbae163f7c55869acce2 100644
--- a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-12.json
+++ b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-12.json
@@ -2,7 +2,7 @@
   "architecture": {
     "platform_type": "x86_64",
     "smp_size": 2,
-    "smt_size": 4
+    "smt_size": 8
   },
   "bios": {
     "release_date": "08/10/2007",
@@ -90,7 +90,7 @@
   "supported_job_types": {
     "besteffort": true,
     "deploy": true,
-    "virtual": null
+    "virtual": "ivt"
   },
   "type": "node",
   "uid": "granduc-12"
diff --git a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-13.json b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-13.json
index 69561e817b80a41e7645f073b1abfcf7d4988ed3..aece2306680915c87df6ce2e77da59eba0c1d12e 100644
--- a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-13.json
+++ b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-13.json
@@ -2,7 +2,7 @@
   "architecture": {
     "platform_type": "x86_64",
     "smp_size": 2,
-    "smt_size": 4
+    "smt_size": 8
   },
   "bios": {
     "release_date": "08/10/2007",
@@ -90,7 +90,7 @@
   "supported_job_types": {
     "besteffort": true,
     "deploy": true,
-    "virtual": null
+    "virtual": "ivt"
   },
   "type": "node",
   "uid": "granduc-13"
diff --git a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-14.json b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-14.json
index 82927348d6c6b46884779ec4501af82688c92436..de010e8b368418466cb3e2a3ccb4653d222ceaa5 100644
--- a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-14.json
+++ b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-14.json
@@ -2,7 +2,7 @@
   "architecture": {
     "platform_type": "x86_64",
     "smp_size": 2,
-    "smt_size": 4
+    "smt_size": 8
   },
   "bios": {
     "release_date": "08/10/2007",
@@ -90,7 +90,7 @@
   "supported_job_types": {
     "besteffort": true,
     "deploy": true,
-    "virtual": null
+    "virtual": "ivt"
   },
   "type": "node",
   "uid": "granduc-14"
diff --git a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-15.json b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-15.json
index 3cdc05c655b4e0223434319cebf7dc8493a47256..68530ee31c3a706d4861199d9e8ea956a6247995 100644
--- a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-15.json
+++ b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-15.json
@@ -2,7 +2,7 @@
   "architecture": {
     "platform_type": "x86_64",
     "smp_size": 2,
-    "smt_size": 4
+    "smt_size": 8
   },
   "bios": {
     "release_date": "08/10/2007",
@@ -90,7 +90,7 @@
   "supported_job_types": {
     "besteffort": true,
     "deploy": true,
-    "virtual": null
+    "virtual": "ivt"
   },
   "type": "node",
   "uid": "granduc-15"
diff --git a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-16.json b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-16.json
index aa8dbfe715abfbf8973bb217751f7e6a2919892c..81a5e0fbcb08b83ba324836d07212e170ccb140c 100644
--- a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-16.json
+++ b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-16.json
@@ -2,7 +2,7 @@
   "architecture": {
     "platform_type": "x86_64",
     "smp_size": 2,
-    "smt_size": 4
+    "smt_size": 8
   },
   "bios": {
     "release_date": "08/10/2007",
@@ -90,7 +90,7 @@
   "supported_job_types": {
     "besteffort": true,
     "deploy": true,
-    "virtual": null
+    "virtual": "ivt"
   },
   "type": "node",
   "uid": "granduc-16"
diff --git a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-17.json b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-17.json
index b914f7e52f88cd3e069dc081d383ad749e23ab71..ca34d6daf28c487ce71a00fbf4738ceb22a71057 100644
--- a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-17.json
+++ b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-17.json
@@ -2,7 +2,7 @@
   "architecture": {
     "platform_type": "x86_64",
     "smp_size": 2,
-    "smt_size": 4
+    "smt_size": 8
   },
   "bios": {
     "release_date": "10/27/2007",
@@ -90,7 +90,7 @@
   "supported_job_types": {
     "besteffort": true,
     "deploy": true,
-    "virtual": null
+    "virtual": "ivt"
   },
   "type": "node",
   "uid": "granduc-17"
diff --git a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-18.json b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-18.json
index afd3e166377d124c56cb362c016b6fde6f6d2cf5..bf9f553a40e496b7abc357877042bc0ec70030a2 100644
--- a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-18.json
+++ b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-18.json
@@ -2,7 +2,7 @@
   "architecture": {
     "platform_type": "x86_64",
     "smp_size": 2,
-    "smt_size": 4
+    "smt_size": 8
   },
   "bios": {
     "release_date": "10/27/2007",
@@ -90,7 +90,7 @@
   "supported_job_types": {
     "besteffort": true,
     "deploy": true,
-    "virtual": null
+    "virtual": "ivt"
   },
   "type": "node",
   "uid": "granduc-18"
diff --git a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-19.json b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-19.json
index 480f128c34523a902734b89363f7bd59d7519acc..86240280ce05d52297cdb4810290e145d46ca675 100644
--- a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-19.json
+++ b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-19.json
@@ -2,7 +2,7 @@
   "architecture": {
     "platform_type": "x86_64",
     "smp_size": 2,
-    "smt_size": 4
+    "smt_size": 8
   },
   "bios": {
     "release_date": "08/10/2007",
@@ -90,7 +90,7 @@
   "supported_job_types": {
     "besteffort": true,
     "deploy": true,
-    "virtual": null
+    "virtual": "ivt"
   },
   "type": "node",
   "uid": "granduc-19"
diff --git a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-2.json b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-2.json
index bb129162913b609f447182a38f33f838cd9f8b50..c5e55960506c02a04d94981c340eb22e0b002405 100644
--- a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-2.json
+++ b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-2.json
@@ -2,7 +2,7 @@
   "architecture": {
     "platform_type": "x86_64",
     "smp_size": 2,
-    "smt_size": 4
+    "smt_size": 8
   },
   "bios": {
     "release_date": "08/10/2007",
@@ -90,7 +90,7 @@
   "supported_job_types": {
     "besteffort": true,
     "deploy": true,
-    "virtual": null
+    "virtual": "ivt"
   },
   "type": "node",
   "uid": "granduc-2"
diff --git a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-20.json b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-20.json
index f8b739891b32781db8d3206757a752423dbeac9b..8cc04caf2c93e46c5c4be61e4e4ba2f115f107c2 100644
--- a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-20.json
+++ b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-20.json
@@ -2,7 +2,7 @@
   "architecture": {
     "platform_type": "x86_64",
     "smp_size": 2,
-    "smt_size": 4
+    "smt_size": 8
   },
   "bios": {
     "release_date": "08/10/2007",
@@ -90,7 +90,7 @@
   "supported_job_types": {
     "besteffort": true,
     "deploy": true,
-    "virtual": null
+    "virtual": "ivt"
   },
   "type": "node",
   "uid": "granduc-20"
diff --git a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-21.json b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-21.json
index c337107c7e20dc8dea6855e5a86e0f5aa850a656..bafe50d2ea4b0662df23c819ef48d363afb2226d 100644
--- a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-21.json
+++ b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-21.json
@@ -2,7 +2,7 @@
   "architecture": {
     "platform_type": "x86_64",
     "smp_size": 2,
-    "smt_size": 4
+    "smt_size": 8
   },
   "bios": {
     "release_date": "10/27/2007",
@@ -90,7 +90,7 @@
   "supported_job_types": {
     "besteffort": true,
     "deploy": true,
-    "virtual": null
+    "virtual": "ivt"
   },
   "type": "node",
   "uid": "granduc-21"
diff --git a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-22.json b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-22.json
index afc205b19ddb8d0a7f37c4d164d2f3517a650013..f2e729a397c178f69abccbadb746d4909e0f4c84 100644
--- a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-22.json
+++ b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-22.json
@@ -2,7 +2,7 @@
   "architecture": {
     "platform_type": "x86_64",
     "smp_size": 2,
-    "smt_size": 4
+    "smt_size": 8
   },
   "bios": {
     "release_date": "10/27/2007",
@@ -90,7 +90,7 @@
   "supported_job_types": {
     "besteffort": true,
     "deploy": true,
-    "virtual": null
+    "virtual": "ivt"
   },
   "type": "node",
   "uid": "granduc-22"
diff --git a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-3.json b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-3.json
index 959ed1fbbd9e59a84c08d8a29429ec8e757e00d2..fa53c91bfc2771673171f82e9038343e26b7ee16 100644
--- a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-3.json
+++ b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-3.json
@@ -2,7 +2,7 @@
   "architecture": {
     "platform_type": "x86_64",
     "smp_size": 2,
-    "smt_size": 4
+    "smt_size": 8
   },
   "bios": {
     "release_date": "10/27/2007",
@@ -90,7 +90,7 @@
   "supported_job_types": {
     "besteffort": true,
     "deploy": true,
-    "virtual": null
+    "virtual": "ivt"
   },
   "type": "node",
   "uid": "granduc-3"
diff --git a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-4.json b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-4.json
index 52b0c86815206b8fafdb787fd7aca9c865122824..16063eb49c97eeeb429524bd4ac3b8287c8a18f9 100644
--- a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-4.json
+++ b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-4.json
@@ -2,7 +2,7 @@
   "architecture": {
     "platform_type": "x86_64",
     "smp_size": 2,
-    "smt_size": 4
+    "smt_size": 8
   },
   "bios": {
     "release_date": "10/27/2007",
@@ -90,7 +90,7 @@
   "supported_job_types": {
     "besteffort": true,
     "deploy": true,
-    "virtual": null
+    "virtual": "ivt"
   },
   "type": "node",
   "uid": "granduc-4"
diff --git a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-5.json b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-5.json
index dbbe2e885049b1e09d721e545ea0d0ba4a1952ec..c3ce9d9709a5a06ffde0453a7e5e8f1242af14a4 100644
--- a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-5.json
+++ b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-5.json
@@ -2,7 +2,7 @@
   "architecture": {
     "platform_type": "x86_64",
     "smp_size": 2,
-    "smt_size": 4
+    "smt_size": 8
   },
   "bios": {
     "release_date": "08/10/2007",
@@ -90,7 +90,7 @@
   "supported_job_types": {
     "besteffort": true,
     "deploy": true,
-    "virtual": null
+    "virtual": "ivt"
   },
   "type": "node",
   "uid": "granduc-5"
diff --git a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-6.json b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-6.json
index d7b10e9b9edbab54c81fd7df0de46b132797c3e6..0bd20b308ce56d60bba8aafd455d73a87db0d912 100644
--- a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-6.json
+++ b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-6.json
@@ -2,7 +2,7 @@
   "architecture": {
     "platform_type": "x86_64",
     "smp_size": 2,
-    "smt_size": 4
+    "smt_size": 8
   },
   "bios": {
     "release_date": "10/27/2007",
@@ -90,7 +90,7 @@
   "supported_job_types": {
     "besteffort": true,
     "deploy": true,
-    "virtual": null
+    "virtual": "ivt"
   },
   "type": "node",
   "uid": "granduc-6"
diff --git a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-7.json b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-7.json
index 3927821b74707eeac9b8d652b9269c45c14e3b9e..995fe3a7d34d904d3a0f697254694467e8f06ccc 100644
--- a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-7.json
+++ b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-7.json
@@ -2,7 +2,7 @@
   "architecture": {
     "platform_type": "x86_64",
     "smp_size": 2,
-    "smt_size": 4
+    "smt_size": 8
   },
   "bios": {
     "release_date": "08/10/2007",
@@ -90,7 +90,7 @@
   "supported_job_types": {
     "besteffort": true,
     "deploy": true,
-    "virtual": null
+    "virtual": "ivt"
   },
   "type": "node",
   "uid": "granduc-7"
diff --git a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-8.json b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-8.json
index a92ddee9fbb9eeb2cfade9b855530069840e8ae4..5d30f2a59d3e097523a180eee66ee752f7857f68 100644
--- a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-8.json
+++ b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-8.json
@@ -2,7 +2,7 @@
   "architecture": {
     "platform_type": "x86_64",
     "smp_size": 2,
-    "smt_size": 4
+    "smt_size": 8
   },
   "bios": {
     "release_date": "08/10/2007",
@@ -90,7 +90,7 @@
   "supported_job_types": {
     "besteffort": true,
     "deploy": true,
-    "virtual": null
+    "virtual": "ivt"
   },
   "type": "node",
   "uid": "granduc-8"
diff --git a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-9.json b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-9.json
index 8708ed7d497a1d5ebc405efe17e7609cb99aa9d4..2cc234cb3d1613ba03d9e383602547ff81742e7d 100644
--- a/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-9.json
+++ b/data/grid5000/sites/luxembourg/clusters/granduc/nodes/granduc-9.json
@@ -2,7 +2,7 @@
   "architecture": {
     "platform_type": "x86_64",
     "smp_size": 2,
-    "smt_size": 4
+    "smt_size": 8
   },
   "bios": {
     "release_date": "08/10/2007",
@@ -90,7 +90,7 @@
   "supported_job_types": {
     "besteffort": true,
     "deploy": true,
-    "virtual": null
+    "virtual": "ivt"
   },
   "type": "node",
   "uid": "granduc-9"
diff --git a/generators/input/luxembourg-granduc.rb b/generators/input/luxembourg-granduc.rb
index 6b576752a5408cc9a0abcb8b6207100122b1e64f..0e9d227cdd114c61e2bada9149f08bc725598517 100644
--- a/generators/input/luxembourg-granduc.rb
+++ b/generators/input/luxembourg-granduc.rb
@@ -6,7 +6,7 @@ site :luxembourg do |site_uid|
 
     22.times do |i|
       node "#{cluster_uid}-#{i+1}" do |node_uid|
-        supported_job_types({:deploy => true, :besteffort => true, :virtual => ivt})
+        supported_job_types({:deploy => true, :besteffort => true, :virtual => "ivt"})
         architecture({
           :smp_size       => 2,
           :smt_size       => 8,