diff --git a/nodes/ceph.py b/nodes/ceph.py
index c5a9288..216f30d 100644
--- a/nodes/ceph.py
+++ b/nodes/ceph.py
@@ -1,111 +1,71 @@
 """ Collect data about ceph nodes"""
 import json
 
-import sh
 from node import Node
+from disk_perf_test_tool.ext_libs import sh
 
 
 def discover_ceph_node():
     """ Return list of ceph's nodes ips """
-    
     ips = {}
-    osd_list = get_osds_list()
-    osd_ips = get_osds_ips(osd_list)
+
+    osd_ips = get_osds_ips(get_osds_list())
     mon_ips = get_mons_or_mds_ips("mon")
     mds_ips = get_mons_or_mds_ips("mds")
+
     for ip in osd_ips:
         url = "ssh://%s" % ip
-        if url in ips:
-            ips[url].append("ceph-osd")
-        else:
-            ips[url] = ["ceph-osd"]
+        ips.setdefault(url, []).append("ceph-osd")
+
     for ip in mon_ips:
         url = "ssh://%s" % ip
-        if url in ips:
-            ips[url].append("ceph-mon")
-        else:
-            ips[url] = ["ceph-mon"]
+        ips.setdefault(url, []).append("ceph-mon")
+
     for ip in mds_ips:
         url = "ssh://%s" % ip
-        if url in ips:
-            ips[url].append("ceph-mds")
-        else:
-            ips[url] = ["ceph-mds"]
+        ips.setdefault(url, []).append("ceph-mds")
 
-    res = []
-    for url, roles in ips:
-        res.append(Node(ip=url, roles=list(roles)))
-
-    return res
-
-
-# internal services
-
-
-class CephException(Exception):
-    """ Exceptions from ceph call"""
-    pass
-
-class ParameterException(Exception):
-    """ Bad parameter in function"""
-    pass
+    return [Node(ip=url, roles=list(roles)) for url, roles in ips.items()]
 
 
 def get_osds_list():
     """ Get list of osds id"""
-    try:
-        res = sh.ceph.osd.ls()
-        osd_list = [osd_id
-                    for osd_id in res.split("\n") if osd_id != '']
-        return osd_list
-    except sh.CommandNotFound:
-        raise CephException("Ceph command not found")
-    except:
-        raise CephException("Ceph command 'osd ls' execution error")
+    return filter(None, sh.ceph.osd.ls().split("\n"))
 
 
 def get_mons_or_mds_ips(who):
     """ Return mon ip list
         :param who - "mon" or "mds" """
-    try:
-        ips = set()
-        if who == "mon":
-            res = sh.ceph.mon.dump()
-        elif who == "mds":
-            res = sh.ceph.mds.dump()
-        else:
-            raise ParameterException("'%s' in get_mons_or_mds_ips instead of mon/mds" % who)
+    if who == "mon":
+        res = sh.ceph.mon.dump()
+    elif who == "mds":
+        res = sh.ceph.mds.dump()
+    else:
+        raise ValueError(("'%s' in get_mons_or_mds_ips instead" +
+                          "of mon/mds") % who)
 
-        line_res = res.split("\n")
-        for line in line_res:
-            fields = line.split()
-            if len(fields) > 2 and who in fields[2]:
-                ips.add(fields[1].split(":")[0])
+    line_res = res.split("\n")
+    ips = set()
 
-        return ips
+    for line in line_res:
+        fields = line.split()
 
-    except sh.CommandNotFound:
-        raise CephException("Ceph command not found")
-    except ParameterException as e:
-        raise e
-    except:
-        mes = "Ceph command '%s dump' execution error" % who
-        raise CephException(mes)
+        # what does fields[1], fields[2] means?
+        # make this code looks like:
+        # SOME_MENINGFULL_VAR1, SOME_MENINGFULL_VAR2 = line.split()[1:3]
+
+        if len(fields) > 2 and who in fields[2]:
+            ips.add(fields[1].split(":")[0])
+
+    return ips
 
 
 def get_osds_ips(osd_list):
-    """ Get osd's ips 
+    """ Get osd's ips
         :param osd_list - list of osd names from osd ls command"""
-    try:
-        ips = set()
-        for osd_id in osd_list:
-            res = sh.ceph.osd.find(osd_id)
-            ip = json.loads(str(res))["ip"]
-            ips.add(ip.split(":")[0])
-        return ips
-
-    except sh.CommandNotFound:
-        raise CephException("Ceph command not found")
-    except:
-        raise CephException("Ceph command 'osd find' execution error")
-
+    ips = set()
+    for osd_id in osd_list:
+        res = sh.ceph.osd.find(osd_id)
+        ip = json.loads(str(res))["ip"]
+        ips.add(ip.split(":")[0])
+    return ips