diff --git a/defaults/solr/solrconfig.xml b/defaults/solr/solrconfig.xml
index 200cbe52b..05b5b46a9 100755
--- a/defaults/solr/solrconfig.xml
+++ b/defaults/solr/solrconfig.xml
@@ -118,9 +118,10 @@
      solr.RAMDirectoryFactory is memory based, not
      persistent, and doesn't work with replication.
      -->
-    <!-- <directoryFactory name="DirectoryFactory" class="${solr.directoryFactory:solr.NRTCachingDirectoryFactory}"/> -->
-    <directoryFactory name="DirectoryFactory" class="${solr.directoryFactory:solr.MMapDirectoryFactory}"/>
-    <!-- using MMapDirectoryFactory as solution for ClosedChannelException given in https://issues.apache.org/jira/browse/SOLR-2247 -->
+    <directoryFactory name="DirectoryFactory" class="${solr.directoryFactory:solr.NRTCachingDirectoryFactory}"/>
+    <!-- <directoryFactory name="DirectoryFactory" class="${solr.directoryFactory:solr.MMapDirectoryFactory}"/> -->
+    <!-- using MMapDirectoryFactory as solution for ClosedChannelException given in https://issues.apache.org/jira/browse/SOLR-2247
+         this feature is now switched on in the startYACY.sh file using a -D option -->
     
     <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      Index Config - These settings control low-level behavior of indexing
@@ -149,7 +150,7 @@
          before flushing.
          If both ramBufferSizeMB and maxBufferedDocs is set, then
          Lucene will flush based on whichever limit is hit first.  -->
-        <!-- <ramBufferSizeMB>256</ramBufferSizeMB> -->
+        <!-- <ramBufferSizeMB>32</ramBufferSizeMB> -->
         <!-- <maxBufferedDocs>1000</maxBufferedDocs> -->
         
         <!-- Expert: Merge Policy
@@ -173,9 +174,7 @@
          will be allowed before they are merged into one.
          Default is 10 for both merge policies.
          -->
-        <!--
          <mergeFactor>4</mergeFactor>
-         -->
         
         <!-- Expert: Merge Scheduler
          The Merge Scheduler in Lucene controls how merges are
diff --git a/startYACY.sh b/startYACY.sh
index 8e80a8f56..5685f8dc3 100755
--- a/startYACY.sh
+++ b/startYACY.sh
@@ -138,6 +138,9 @@ then
     JAVA_ARGS="$JAVA_ARGS -XX:+UseLargePages"
 fi
 
+#turn on MMap for Solr if OS is a 64bit OS
+if [ -n "`uname -m | grep 64`" ]; then JAVA_ARGS="$JAVA_ARGS -Dsolr.directoryFactory=solr.MMapDirectoryFactory"; fi
+
 if [ ! -f $CONFIGFILE -a -f DATA/SETTINGS/httpProxy.conf ]
 then
 	# old config if new does not exist