diff --git a/README.md b/README.md
index b8f9cd2..ca12f99 100644
--- a/README.md
+++ b/README.md
@@ -49,6 +49,46 @@ deployment:
 
 A minimium cluster size of three units is recommended.
 
+Memory Configuration
+-------------------
+
+Percona Cluster is extremely memory sensitive. Setting memory values too low
+will give poor performance. Setting them too high will create problems that are
+very difficult to diagnose. Please take time to evaluate these settings for
+each deployment environment rather than copying and pasting bundle
+configurations.
+
+The Percona Cluster charm needs to be able to be deployed in small low memory
+development environments as well as high performance production environments.
+The charm configuration opinionated defaults favor the developer environment in
+order to ease initial testing. Production environments need to consider
+carefully the memory requirements for the hardware or cloud in use. Consult a
+MySQL memory calculator [2] to understand the implications of the values.
+
+Between the 5.5 and 5.6 releases a significant default was changed.
+The performance schema [1] defaulted to on for 5.6 and later. This allocates
+all the memory that would be required to handle max-connections plus several
+other memory settings. With 5.5 memory was allocated during runtime as needed.
+
+The charm now makes performance schema configurable and defaults to off (False).
+With the performance schema turned off memory is allocated when needed during
+run time. It is important to understand this can lead to run time memory
+exhaustion if the configuration values are set too high. Consult a MySQL memory
+calculator [2] to understand the implications of the values.
+
+Particularly consider the max-connections setting, this value is a balance
+between connection exhaustion and memory exhaustion. Occasionally connection
+exhaustion occurs in large production HA clouds with max-connections less than
+2000. The common practice became to set max-connections unrealistically high
+near 10k or 20k. In the move to 5.6 on Xenial this became a problem as Percona
+would fail to start up or behave erratically as memory exhaustion occurred on
+the host due to performance schema being turned on. Even with the default now
+turned off this value should be carefully considered against the production
+requirements and resources available.
+
+[1] http://dev.mysql.com/doc/relnotes/mysql/5.6/en/news-5-6-6.html#mysqld-5-6-6-performance-schema 
+[2] http://www.mysqlcalculator.com/
+
 
 HA/Clustering
 -------------
diff --git a/config.yaml b/config.yaml
index c9b235c..4bf12fb 100644
--- a/config.yaml
+++ b/config.yaml
@@ -47,6 +47,13 @@ options:
       Maximum connections to allow. A value of -1 means use the server's
       compiled-in default.  This is not typically that useful so the
       charm will configure PXC with a default max-connections value of 600.
+      Note: Connections take up memory resources. Either at startup time with
+      performance-schema=True or during run time with performance-schema=False.
+      This value is a balance between connection exhaustion and memory
+      exhaustion.
+      Consult a MySQL memory calculator like http://www.mysqlcalculator.com/ to
+      understand memory resources consumed by connections.
+      See also performance-schema.
   wait-timeout:
     type: int
     default: -1
@@ -207,3 +214,17 @@ options:
       Sets the expire_logs_days mysql configuration option, which will make
       mysql server automatically remove logs older than configured number of
       days.
+  performance-schema:
+    default: False
+    type: boolean
+    description: |
+      The performance schema attempts to automatically size the values of
+      several of its parameters at server startup if they are not set
+      explicitly. When set to on (True) memory is allocated at startup time.
+      The implications of this is any memory related charm config options such
+      as max-connections and innodb-buffer-pool-size must be explicitly set for
+      the environment percona is running in or percona may fail to start.
+      Default to off (False) at startup time giving 5.5 like behavior. The
+      implication of this is one can set configuration values that could lead
+      to memory exhaustion during run time as memory is not allocated at
+      startup time.
diff --git a/hooks/percona_hooks.py b/hooks/percona_hooks.py
index b1bdd65..067e41f 100755
--- a/hooks/percona_hooks.py
+++ b/hooks/percona_hooks.py
@@ -150,6 +150,7 @@ def render_config(clustered=False, hosts=None):
         'enable_binlogs': config('enable-binlogs'),
         'binlogs_max_size': config('binlogs-max-size'),
         'binlogs_expire_days': config('binlogs-expire-days'),
+        'performance_schema': config('performance-schema'),
     }
 
     if config('prefer-ipv6'):
diff --git a/templates/mysqld.cnf b/templates/mysqld.cnf
index bc3f409..b75a5f4 100644
--- a/templates/mysqld.cnf
+++ b/templates/mysqld.cnf
@@ -114,6 +114,15 @@ wsrep_sst_auth="sstuser:{{ sst_password }}"
 wsrep_provider_options = {{ wsrep_provider_options }}
 {% endif %}
 
+#
+# * Performance Schema
+#
+{% if performance_schema -%}
+performance_schema=On
+{% else -%}
+performance_schema=Off
+{% endif %}
+
 #
 # * IPv6 SST configuration
 #
diff --git a/tests/basic_deployment.py b/tests/basic_deployment.py
index 1710c85..6591080 100644
--- a/tests/basic_deployment.py
+++ b/tests/basic_deployment.py
@@ -1,6 +1,7 @@
 import amulet
 import re
 import os
+import socket
 import time
 import telnetlib
 import yaml
@@ -41,7 +42,8 @@ class BasicDeployment(OpenStackAmuletDeployment):
            compatible with the local charm (e.g. stable or next).
            """
         this_service = {'name': 'percona-cluster',
-                        'units': self.units}
+                        'units': self.units,
+                        'constraints': {'mem': '3072M'}}
         other_services = []
         if self.units > 1:
             other_services.append({'name': 'hacluster'})
@@ -185,10 +187,10 @@ class BasicDeployment(OpenStackAmuletDeployment):
         try:
             telnetlib.Telnet(addr, port)
             return True
-        except TimeoutError:  # noqa this exception only available in py3
-            print("ERROR: could not connect to %s:%s" % (addr, port))
-            return False
-        except ConnectionRefusedError:  # noqa - also only in py3
-            print("ERROR: connection refused connecting to %s:%s" % (addr,
-                                                                     port))
+        except socket.error as e:
+            if e.errno == 113:
+                print("ERROR: could not connect to %s:%s" % (addr, port))
+            if e.errno == 111:
+                print("ERROR: connection refused connecting to %s:%s" % (addr,
+                                                                         port))
             return False