adding entity for migration basics

git-svn-id: http://svn.suse.de/svn/doc/trunk/cloud/en@58037 2463f871-af05-0410-bd21-ebfa852e3ce4

Author: taroth21

xml/phrases-decl.ent

@@ -713,7 +713,8 @@ to cloud administrators or cloud operators only.</para>
 <!ENTITY inst-terminate
 ' <para>For maintenance reasons, you can pause or suspend images&mdash;provided
     they are running on &kvm; or &xen;. Pausing or suspending avoids the consequences 
-    that come with terminating an instance.</para>
+    that come with terminating an instance. Instances running on &vmware; or
+    &hyper; can only be suspended, but not paused.</para>
    <para>If you pause an instance, the content of the virtual machine is stored
     to memory (RAM) and the image is kept running in a <quote>frozen</quote>
     state. When suspending an instance, the content of the virtual 
@@ -1202,3 +1203,50 @@ addresses.</para>'>
   -v "<replaceable>URL</replaceable>" \
   /etc/crowbar/provisioner.json</screen>
  </note>'>
+ 
+ <!ENTITY migration
+ ' <para>The term <literal>migration</literal> in &ostack; refers to the
+    process of moving a virtual machine instance from one &compnode; to
+    another. &ostack; discriminates between two types of migration:</para>
+   <variablelist>
+    <varlistentry>
+     <term>Offline (Non-live) Migration</term>
+     <listitem>
+      <para>
+       <remark>taroth 2013-09-09: DEVs, is the following correct?</remark>
+       The instance will be shut down in order to be moved to another
+       &compnode;, leading to instance downtime and all consequences of
+       shutting down an instance. The destination of the instance cannot be
+       defined by the cloud administrator, instead it is picked by the nova
+       scheduler.
+      </para>
+     </listitem>
+    </varlistentry>
+    <varlistentry>
+     <term>Live Migration</term>
+     <listitem>
+      <para>
+       <remark>taroth 2013-09-09: DEVs, is the following correct?</remark>
+       During the move to another &compnode; there is only very little
+       downtime of the virtual machine instance. However, if the default
+       configuration options in &ostack; &comp; are used, the instance
+       will be suspended before migration. When executing a live migration, the
+       cloud administrator has to select to which &compnode; to move the
+       instance.</para>
+      <para>For live migrations, we need to discriminate between the following
+      scenarios</para>
+      <itemizedlist>
+       <listitem>
+        <para>Live migration on shared storage. In this case, both &compnode;s have access
+         to a shared storage. </para>
+       </listitem>
+       <listitem>
+        <para>Live migration without shared storage (block migration). In this
+         case, no shared storage is required.</para>
+       </listitem>
+      </itemizedlist>
+       </para>
+     </listitem>
+    </varlistentry>
+   </variablelist>'>
+