Reverted setting of MMapDirectoryFactory from solrconfig; see

http://forum.yacy-websuche.de/viewtopic.php?p=27509#p27509
Instead, in the start script is checked if the host is a 64 host and
-Dsolr.directoryFactory=solr.MMapDirectoryFactory is set as java option

Reverted the ramBufferSizeMB setting (this was not enabled anyway)
because that may be too much memory for small peers and embedded
systems.

Activated the mergeFactor 4; this was commented out by mistake

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

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