diff --git a/tempest/common/utils/linux/remote_client.py b/tempest/common/utils/linux/remote_client.py
index 9319d2a..5ab980b 100644
--- a/tempest/common/utils/linux/remote_client.py
+++ b/tempest/common/utils/linux/remote_client.py
@@ -64,10 +64,14 @@
                 # Show header line too
                 selected.append(l)
             # lsblk lists disk type in a column right-aligned with TYPE
-            elif pos > 0 and l[pos:pos + 4] == "disk":
+            elif pos is not None and pos > 0 and l[pos:pos + 4] == "disk":
                 selected.append(l)
 
-        return "\n".join(selected)
+        if selected:
+            return "\n".join(selected)
+        else:
+            msg = "'TYPE' column is requred but the output doesn't have it: "
+            raise tempest.lib.exceptions.TempestException(msg + output)
 
     def get_boot_time(self):
         cmd = 'cut -f1 -d. /proc/uptime'
diff --git a/tempest/scenario/manager.py b/tempest/scenario/manager.py
index 1ca9365..b692acf 100644
--- a/tempest/scenario/manager.py
+++ b/tempest/scenario/manager.py
@@ -195,7 +195,7 @@
 
         tenant_network = self.get_tenant_network()
 
-        body, servers = compute.create_test_server(
+        body, _ = compute.create_test_server(
             clients,
             tenant_network=tenant_network,
             wait_until=wait_until,
diff --git a/tempest/scenario/test_network_advanced_server_ops.py b/tempest/scenario/test_network_advanced_server_ops.py
index ec6d362..c8add8b 100644
--- a/tempest/scenario/test_network_advanced_server_ops.py
+++ b/tempest/scenario/test_network_advanced_server_ops.py
@@ -62,7 +62,7 @@
         if test.is_extension_enabled('security-group', 'network'):
             security_group = self._create_security_group()
             security_groups = [{'name': security_group['name']}]
-        network, subnet, router = self.create_networks()
+        network, _, _ = self.create_networks()
         server = self.create_server(
             networks=[{'uuid': network['id']}],
             key_name=keypair['name'],
diff --git a/tempest/scenario/test_network_basic_ops.py b/tempest/scenario/test_network_basic_ops.py
index c76c082..9aeedad 100644
--- a/tempest/scenario/test_network_basic_ops.py
+++ b/tempest/scenario/test_network_basic_ops.py
@@ -212,7 +212,7 @@
             self.servers, mtu=mtu)
 
     def _disassociate_floating_ips(self):
-        floating_ip, server = self.floating_ip_tuple
+        floating_ip, _ = self.floating_ip_tuple
         self._disassociate_floating_ip(floating_ip)
         self.floating_ip_tuple = Floating_IP_tuple(
             floating_ip, None)
@@ -287,7 +287,7 @@
                                               "guest after %s sec"
                                               % CONF.network.build_timeout)
 
-        num, new_nic = self.diff_list[0]
+        _, new_nic = self.diff_list[0]
         ssh_client.exec_command("sudo ip addr add %s/%s dev %s" % (
                                 new_port['fixed_ips'][0]['ip_address'],
                                 CONF.network.project_network_mask_bits,
@@ -630,7 +630,7 @@
                 admin_state_up attribute of instance port to True
         """
         self._setup_network_and_servers()
-        floating_ip, server = self.floating_ip_tuple
+        _, server = self.floating_ip_tuple
         server_id = server['id']
         port_id = self.os_admin.ports_client.list_ports(
             device_id=server_id)['ports'][0]['id']
diff --git a/tempest/scenario/test_network_v6.py b/tempest/scenario/test_network_v6.py
index 3504a44..6d9addd 100644
--- a/tempest/scenario/test_network_v6.py
+++ b/tempest/scenario/test_network_v6.py
@@ -171,7 +171,7 @@
 
         # Turn on 2nd NIC for Cirros when dualnet
         if dualnet:
-            network, network_v6 = net_list
+            _, network_v6 = net_list
             self.turn_nic6_on(sshv4_1, sid1, network_v6['id'])
             self.turn_nic6_on(sshv4_2, sid2, network_v6['id'])