diff --git a/nfsometerlib/cmd.py b/nfsometerlib/cmd.py
index 9b6dbdd..a2ebcef 100644
--- a/nfsometerlib/cmd.py
+++ b/nfsometerlib/cmd.py
@@ -25,7 +25,15 @@ class CmdError(Exception):
     pass
 
 class CmdErrorCode(CmdError):
-    pass
+    def __init__(self, cmd, code, errstr):
+        self.cmd = cmd
+        self.code = code
+        self.errstr = errstr
+
+    def __str__(self):
+        return str.format(
+            'command "{:s}" exited with non-zero status: {:d}{:s}',
+            self.cmd, self.code, self.errstr)
 
 class CmdErrorOut(CmdError):
     pass
@@ -67,8 +75,7 @@ def cmd(args, raiseerrorcode=True, raiseerrorout=True, instr='',
         errstr = '\n%s' % errstr
 
     if raiseerrorcode and ret != 0:
-        raise CmdErrorCode('command "%s" exited with non-zero status: %u%s' %
-                            (args, ret, errstr))
+        raise CmdErrorCode(args, ret, errstr)
 
     if raiseerrorout and errstr:
         raise CmdErrorOut('command "%s" has output to stderr: %s' %
diff --git a/nfsometerlib/trace.py b/nfsometerlib/trace.py
index cd1d3c3..9ce396e 100644
--- a/nfsometerlib/trace.py
+++ b/nfsometerlib/trace.py
@@ -20,6 +20,7 @@ import multiprocessing
 import signal
 import random
 import atexit
+import pwd
 
 from cmd import *
 from config import *
@@ -382,7 +383,7 @@ def _save_start_stats(attrs):
         {'cmd': 'dmesg',
          'file': 'dmesg.start'
         },
-        {'cmd': 'sudo sysctl -a | grep nfs',
+        {'cmd': 'sudo sysctl -a 2>/dev/null | grep nfs',
          'file': 'nfs_sysctls.start'
         },
         {'cmd': 'cat /proc/self/mountstats',
@@ -422,7 +423,7 @@ def _save_stop_stats(attrs):
         {'cmd': 'nfsiostat',
          'file': 'nfsiostat'
         },
-        {'cmd': 'sudo sysctl -a | grep nfs',
+        {'cmd': 'sudo sysctl -a 2>/dev/null | grep nfs',
          'file': 'nfs_sysctls.stop'
         },
         {'cmd': 'sudo klist -ke /etc/krb5.keytab 2> /dev/null || echo',
@@ -517,6 +518,77 @@ def probe_detect(probe_trace_dir, mountopt):
 
     return detect
 
+def _is_auth_gss():
+    lines = [ x.strip() for x in file('/proc/self/mountstats') ]
+    mounted_on = ' mounted on %s with ' % MOUNTDIR
+    start = -1
+    end = -1
+
+    for i, line in enumerate(lines):
+        if line.find(mounted_on) >= 0:
+            assert start == -1
+            start = i
+        elif start >= 0 and line.startswith('device '):
+            assert end == -1
+            end = i
+
+    if end < 0:
+        end = len(lines)
+
+    if start >= 0:
+        lines = lines[start:end]
+    else:
+        return False
+
+    for line in lines:
+        if line.startswith('sec:'):
+            label, data = line.split(':')
+            data = data.strip()
+            if data.startswith('flavor=6'):
+                return True
+    return False
+
+def _has_creds():
+    return os.stat(os.path.join(RUNNING_TRACE_DIR,
+                                'klist_user.start')).st_size != 1
+
+def _has_tkt(server):
+    princ = re.compile('nfs/' + server + '\S+$')
+    lines = [ x.strip() for x in file(os.path.join(RUNNING_TRACE_DIR,
+                                                   'klist_user.start')) ]
+    for i, line in enumerate(lines):
+        if re.search(princ, line):
+            return True
+    return False
+
+def _eperm_helper(opts):
+    server, path = opts.serverpath.split(':')
+    if _is_auth_gss():
+        if _has_creds():
+            if _has_tkt(server):
+                info = str.format(
+                    ' Check {:s} on {:s} and ensure user {:s} has the correct'
+                    ' permission.', path, server,
+                    pwd.getpwuid(os.getuid())[0])
+            else:
+                info = str.format(
+                    ' No nfs service ticket for {:s} in user {:s}\'s'
+                    ' credential cache.', server,
+                    pwd.getpwuid(os.getuid())[0])
+        else:
+            info = str.format(
+                ' User {:s} has no kerberos credentials.',
+                pwd.getpwuid(os.getuid())[0])
+    elif os.getuid() == 0:
+        info = str.format(
+            ' Check for root squashing in the export options for {:s} on'
+            ' {:s}.', path, server)
+    else:
+       info = str.format(
+            ' Check {:s} on {:s} and ensure user {:s} has the correct'
+            ' permission.', path, server, pwd.getpwuid(os.getuid())[0])
+    return info
+
 #
 # public api commands
 #
@@ -746,7 +818,18 @@ def probe_mounts(opts):
         start(m, opts.serverpath, '__nfsometer-probe', [], [], is_probe=True)
         fpath = os.path.join(RUNROOT, '__nfsometer-probe')
 
-        cmd('mkdir -p "%s"' % RUNROOT)
+        try:
+            cmd('mkdir -p "%s"' % RUNROOT)
+        except CmdErrorCode, e:
+            msg = str.format('"mkdir -p {:s}" failed.', RUNROOT)
+            # try to hint why it failed
+            if e.code == errno.EPERM:
+                msg += _eperm_helper(opts)
+            else:
+                msg += e.errstr
+            warn(msg)
+            # and bail out right now
+            sys.exit(1)
 
         f = file(fpath, 'w+')
         f.write('nfsometer probe to determine server features: %s' % m)