diff --git a/cache/stores/memcache/lib.php b/cache/stores/memcache/lib.php
index f83d45f1e9f..e9c6e1d32b6 100644
--- a/cache/stores/memcache/lib.php
+++ b/cache/stores/memcache/lib.php
@@ -69,6 +69,12 @@ class cachestore_memcache extends cache_store implements cache_is_configurable {
      */
     protected $isready = false;
 
+    /**
+     * Set to true once this store instance has been initialised.
+     * @var bool
+     */
+    protected $isinitialised = false;
+
     /**
      * The cache definition this store was initialised for.
      * @var cache_definition
@@ -110,10 +116,7 @@ class cachestore_memcache extends cache_store implements cache_is_configurable {
         foreach ($this->servers as $server) {
             $this->connection->addServer($server[0], $server[1], true, $server[2]);
             // Test the connection to this server.
-            if (@$this->connection->set("$server[0]:$server[1]:$server[2]", 'ping', MEMCACHE_COMPRESSED, 1)) {
-                // We can connect at least to this server.
-                $this->isready = true;
-            }
+            $this->isready = @$this->connection->set("ping", 'ping', MEMCACHE_COMPRESSED, 1);
         }
     }
 
@@ -129,6 +132,7 @@ class cachestore_memcache extends cache_store implements cache_is_configurable {
             throw new coding_exception('This memcache instance has already been initialised.');
         }
         $this->definition = $definition;
+        $this->isinitialised = true;
     }
 
     /**
@@ -137,7 +141,7 @@ class cachestore_memcache extends cache_store implements cache_is_configurable {
      * @return bool
      */
     public function is_initialised() {
-        return ($this->connection !== null);
+        return ($this->isinitialised);
     }
 
     /**
diff --git a/cache/stores/memcached/lib.php b/cache/stores/memcached/lib.php
index 8f2a59ad388..4cad20cb72b 100644
--- a/cache/stores/memcached/lib.php
+++ b/cache/stores/memcached/lib.php
@@ -74,6 +74,12 @@ class cachestore_memcached extends cache_store implements cache_is_configurable
      */
     protected $isready = false;
 
+    /**
+     * Set to true when this store instance has been initialised.
+     * @var bool
+     */
+    protected $isinitialised = false;
+
     /**
      * The cache definition this store was initialised with.
      * @var cache_definition
@@ -134,13 +140,7 @@ class cachestore_memcached extends cache_store implements cache_is_configurable
                 $this->connection->setOption($key, $value);
             }
             $this->connection->addServers($this->servers);
-            foreach ($this->servers as $server) {
-                // Test the connection to this server.
-                if (@$this->connection->set("$server[0]:$server[1]:$server[2]", 'ping', MEMCACHE_COMPRESSED, 1)) {
-                    // We can connect at least to this server.
-                    $this->isready = true;
-                }
-            }
+            $this->isready = @$this->connection->set("ping", 'ping', 1);
         }
     }
 
@@ -156,6 +156,7 @@ class cachestore_memcached extends cache_store implements cache_is_configurable
             throw new coding_exception('This memcached instance has already been initialised.');
         }
         $this->definition = $definition;
+        $this->isinitialised = true;
     }
 
     /**
@@ -164,7 +165,7 @@ class cachestore_memcached extends cache_store implements cache_is_configurable
      * @return bool
      */
     public function is_initialised() {
-        return ($this->connection !== null);
+        return ($this->isinitialised);
     }
 
     /**
diff --git a/cache/stores/mongodb/lib.php b/cache/stores/mongodb/lib.php
index 36aed49eae0..2385d5e5682 100644
--- a/cache/stores/mongodb/lib.php
+++ b/cache/stores/mongodb/lib.php
@@ -132,10 +132,9 @@ class cachestore_mongodb extends cache_store implements cache_is_configurable {
 
         try {
             $this->connection = new Mongo($this->server, $this->options);
-            $this->database = $this->connection->selectDB($this->databasename);
             $this->isready = true;
-        } catch (Exception $e) {
-            // Tipically, a MongoConnectionException.
+        } catch (MongoConnectionException $e) {
+            // We only want to catch MongoConnectionExceptions here.
         }
     }
 
@@ -181,6 +180,7 @@ class cachestore_mongodb extends cache_store implements cache_is_configurable {
         if ($this->is_initialised()) {
             throw new coding_exception('This mongodb instance has already been initialised.');
         }
+        $this->database = $this->connection->selectDB($this->databasename);
         $this->definitionhash = $definition->generate_definition_hash();
         $this->collection = $this->database->selectCollection($this->definitionhash);
         $this->collection->ensureIndex(array('key' => 1), array(
diff --git a/cache/stores/session/lib.php b/cache/stores/session/lib.php
index 383dae17c8a..8cb42f0d0e0 100644
--- a/cache/stores/session/lib.php
+++ b/cache/stores/session/lib.php
@@ -361,7 +361,6 @@ class cachestore_session extends session_data_store implements cache_is_key_awar
      */
     public function purge() {
         $this->store = array();
-
         return true;
     }