diff --git a/nxc/my_scripts.nix b/nxc/my_scripts.nix
index e1c10f84f35981f82b9a95e0236b27a6b20f5941..bb50b694e7d32198c0d9e977b19545795ca614fb 100644
--- a/nxc/my_scripts.nix
+++ b/nxc/my_scripts.nix
@@ -26,8 +26,10 @@ in {
       cd ${nfsMountPoint}
       cp ${iorConfig} ${iorConfigPerCluster}
       NB_TASKS=$1
+      BLOCK_SIZE=$2
 
       sed -ri "s/(numTasks)=\w+/\1=$NB_TASKS/g" ${iorConfigPerCluster}
+      sed -ri "s/(blockSize)=\w+/\1=$BLOCK_SIZE/g" ${iorConfigPerCluster}
   '';
 
   start_ior_nodes =
@@ -39,9 +41,10 @@ in {
 
       NB_SLOTS_PER_NODE=$(($TOTAL_NB_NODES / $NB_NODES))
 
-      cat /etc/hosts | grep node | head -n $NB_NODES | awk -v nb_slots="$NB_SLOTS_PER_NODE" '{ print $2 " slots=" nb_slots;}' > my_hosts
+      cat /etc/hosts | grep client | head -n $NB_NODES | awk -v nb_slots="$NB_SLOTS_PER_NODE" '{ print $2 " slots=" nb_slots;}' > my_hosts
 
-      mpirun --allow-run-as-root --oversubscribe -mca btl self,vader -np $TOTAL_NB_NODES --hostfile my_hosts ior -f ${iorConfigPerCluster}
+      # mpirun --allow-run-as-root --oversubscribe -mca btl self,vader -np $TOTAL_NB_NODES --hostfile my_hosts ior -f ${iorConfigPerCluster}
+      mpirun --allow-run-as-root --oversubscribe --mca pml ^ucx --mca mtl ^psm2,ofi --mca btl ^ofi,openib -np $TOTAL_NB_NODES --hostfile my_hosts ior -f ${iorConfigPerCluster}
     '';
     
   gen_config_orangefs = 
diff --git a/nxc/script.py b/nxc/script.py
index 8d0a37228cfffc66613623382aebcd073ff7d389..d5f8cedba87dae8b8be4151f3c3fc65a16a90400 100644
--- a/nxc/script.py
+++ b/nxc/script.py
@@ -16,6 +16,7 @@ class MyEngine(Engine):
         parser.add_argument('--nxc_build_file', help='Path to the NXC deploy file')
         parser.add_argument('--nb_cpu_nodes', help='Number of compute nodes')
         parser.add_argument('--nb_io_nodes', help='Number of io nodes')
+        parser.add_argument('--block_size', help='File size to write')
         parser.add_argument('--walltime', help='walltime in hours')
         parser.add_argument('--result_dir', help='where to store results')
         parser.add_argument('--flavour', help='Flavour')
@@ -26,23 +27,25 @@ class MyEngine(Engine):
         self.nb_io_nodes  = -1
         self.nb_nodes = -1
         self.flavour = None
+        self.block_size = None
 
     def init(self):
         self.nb_cpu_nodes = int(self.args.nb_cpu_nodes) if self.args.nb_cpu_nodes else 2
         self.nb_io_nodes  = int(self.args.nb_io_nodes)  if self.args.nb_io_nodes else 1
         self.nb_nodes = self.nb_cpu_nodes + self.nb_io_nodes
+        self.block_size = self.args.block_size if self.args.block_size else "1G"
 
         walltime_hours = float(self.args.walltime) if self.args.walltime else 1
         nxc_build_file = self.args.nxc_build_file
         self.flavour = self.args.flavour if self.args.flavour else "g5k-image"
 
-        site = "grenoble"
-        cluster = "dahu"
+        site = "nancy"
+        cluster = "gros"
 
         oar_job = reserve_nodes(self.nb_nodes, site, cluster, "deploy" if self.flavour == "g5k-image" else "allow_classic_ssh",  walltime=walltime_hours*60*60)
         self.oar_job_id, site = oar_job[0]
 
-        roles_quantities = {"serverfs": self.nb_io_nodes, "node": self.nb_cpu_nodes}
+        roles_quantities = {"serverfs": self.nb_io_nodes, "client": self.nb_cpu_nodes}
 
         self.nodes = get_oar_job_nodes_nxc(
             self.oar_job_id,
@@ -55,7 +58,7 @@ class MyEngine(Engine):
     def run(self):
         result_dir = self.args.result_dir if self.args.result_dir else os.getcwd()
 
-        zip_archive_name = f"{result_dir}/results_ior_{self.nb_nodes}_nodes_{self.flavour}"
+        zip_archive_name = f"{result_dir}/results_ior_{self.nb_cpu_nodes}_cpu_nodes_{self.nb_io_nodes}_io_nodes_{self.block_size}_block_size_{self.flavour}"
         outfile = self.args.outfile[:-4] if self.args.outfile else zip_archive_name
 
         folder_name = f"{result_dir}/expe_orangefs_{self.flavour}_{self.nb_nodes}"
@@ -63,24 +66,24 @@ class MyEngine(Engine):
         
         logger.info("Starting OrangeFS on the IO nodes")
         io_nodes = " ".join(f"serverfs{i + 1}" for i in range(self.nb_io_nodes))
-        orangefs_config_remote = Remote(f"start_orangefs {io_nodes}", self.nodes["serverfs"])
+        orangefs_config_remote = Remote(f"start_orangefs {io_nodes}", self.nodes["serverfs"], connection_params={'users': 'root'})
         orangefs_config_remote.run()
         
         logger.info("Starting OrangeFS on the clients")
-        orangefs_config_client_remote = Remote("orangefs_mount serverfs1", self.nodes["node"])
+        orangefs_config_client_remote = Remote("orangefs_mount serverfs1", self.nodes["client"], connection_params={'user': 'root'})
         orangefs_config_client_remote.run()
 
 
         logger.info("Generating IOR config")
-        run_ior_config_remote = Remote(f"generate_ior_config {self.nb_cpu_nodes}", self.nodes["node"][0], connection_params={'user': 'root'})
+        run_ior_config_remote = Remote(f"generate_ior_config {self.nb_cpu_nodes} {self.block_size}", self.nodes["client"][0], connection_params={'user': 'root'})
         run_ior_config_remote.run()
 
-        for nb_node in range(self.nb_nodes - 1, 0, -1):
+        for nb_node in range(self.nb_cpu_nodes, 0, -1):
             is_ok = False
             while not is_ok:
                 # Run IOR
                 logger.info(f"Starting IOR with {nb_node} nodes")
-                run_ior_remote = Remote(f"start_ior_nodes {nb_node} {self.nb_cpu_nodes}", self.nodes["node"][0], connection_params={'user': 'root'})
+                run_ior_remote = Remote(f"start_ior_nodes {nb_node} {self.nb_cpu_nodes}", self.nodes["client"][0], connection_params={'user': 'root'})
                 run_ior_remote.run()
                 is_ok = run_ior_remote.ok
 
@@ -91,7 +94,7 @@ class MyEngine(Engine):
                 # Get the result file back
                 logger.info(f"Retreving the result file for IOR with {nb_node}")
                 get_file_command = f"cp /orangefs/results_ior.json {folder_name}/results_ior_total_{self.nb_nodes}_active_{nb_node}_{self.flavour}.json"
-                get_file_remote = Remote(get_file_command, self.nodes["node"][0], connection_params={'user': 'root'})
+                get_file_remote = Remote(get_file_command, self.nodes["client"][0], connection_params={'user': 'root'})
                 get_file_remote.run()
                 is_ok = get_file_remote.ok
             logger.info(f"Result file for IOR with {nb_node} retrieved")
@@ -101,7 +104,7 @@ class MyEngine(Engine):
         remove_folder(folder_name)
 
         logger.info(f"Giving back the resources")
-        oardel([(self.oar_job_id, "grenoble")])
+        oardel([(self.oar_job_id, "nancy")])
 
 def reserve_nodes(nb_nodes, site, cluster, job_type, walltime=3600):
     jobs = oarsub([(OarSubmission("{{cluster='{}'}}/nodes={}".format(cluster, nb_nodes), walltime, job_type=[job_type]), site)])
diff --git a/nxc/script_ior.nix b/nxc/script_ior.nix
index 590c3040d8d9c0c85dd51714097fed22b68e2990..04df93b790a528e07929233765199bda07bd05a4 100644
--- a/nxc/script_ior.nix
+++ b/nxc/script_ior.nix
@@ -40,11 +40,11 @@ IOR START
 
     repetitions=5
     numTasks=${builtins.toString numTasks}
-    segmentCount=4
+    segmentCount=1
     blockSize=128M
-    transferSize=4M
+    transferSize=1M
 
-    summaryFile=/data/results_ior.json
+    summaryFile=/orangefs/results_ior.json
     summaryFormat=JSON
 RUN
     writeFile=0