diff --git a/benchmark/radosbench.py b/benchmark/radosbench.py
index fc275aa9..cb411eca 100644
--- a/benchmark/radosbench.py
+++ b/benchmark/radosbench.py
@@ -6,6 +6,7 @@
 import time
 import threading
 import logging
+import re
 
 from cluster.ceph import Ceph
 from benchmark import Benchmark
@@ -30,6 +31,7 @@ def __init__(self, cluster, config):
         self.out_dir = '%s/osd_ra-%08d/op_size-%08d/concurrent_ops-%08d' % (self.archive_dir, int(self.osd_ra), int(self.op_size), int(self.concurrent_ops))
         self.pool_profile = config.get('pool_profile', 'default')
         self.cmd_path = config.get('cmd_path', '/usr/bin/rados')
+        self.readmode = config.get('readmode', 'seq')
 
     def exists(self):
         if os.path.exists(self.out_dir):
@@ -65,7 +67,8 @@ def run(self):
         self._run('write', '%s/write' % self.run_dir, '%s/write' % self.out_dir)
         # Run read test unless write_only
         if self.write_only: return
-        self._run('seq', '%s/seq' % self.run_dir, '%s/seq' % self.out_dir)
+        self._run(self.readmode, '%s/%s' % (self.run_dir, self.readmode), '%s/%s' % (self.out_dir, self.readmode))
+        
 
     def _run(self, mode, run_dir, out_dir):
         # We'll always drop caches for rados bench
@@ -73,7 +76,16 @@ def _run(self, mode, run_dir, out_dir):
 
         if self.concurrent_ops:
             concurrent_ops_str = '--concurrent-ios %s' % self.concurrent_ops
-        op_size_str = '-b %s' % self.op_size
+        #determine rados version    
+        rados_version_str = subprocess.check_output(["rados", "-v"])
+        m = re.findall("version (\d+)", rados_version_str)
+        rados_version = int(m[0])
+
+        if mode in ['write'] or rados_version < 9:
+            op_size_str = '-b %s' % self.op_size
+        else:
+            op_size_str = ''
+
 
         common.make_remote_dir(run_dir)