add FAQ section; add restart VM FAQ

Author: Charles Loomis

source/admin-guide/16-faq.rst

@@ -0,0 +1,45 @@
+Frequently Asked Questions
+==========================
+
+This section collects a number of frequently asked questions
+concerning the administration of a StratusLab cloud infrastructure.
+If there are other questions that you would like to see treated here,
+please contact StratusLab support.
+
+How to restart VMs after a power outage?
+----------------------------------------
+
+After the power outage the nodes hosting the virtual machines must be
+restarted.  If this has not happened automatically, ensure that all of
+the nodes have rebooted.
+
+Connect to each of the nodes to ensure that all of the iSCSI mounts
+are present.
+
+::
+    # iscsiadm -m session
+
+If the links are not correctly mounted (bad links will blink in the
+list), then the easiest way to recover this is simply to reboot the
+machine again. 
+
+Once you have verified all of the iSCSI links on all of the nodes,
+then you must log into the frontend machine as `oneadmin`.  As this
+user, you can then force OpenNebula to restart all of the machines in
+the `unknown` state.
+
+The commands for this (assuming that you're logged into the frontend
+as `root`), are:
+
+::
+    # su - oneadmin
+    $ for vm in `onevm list all |grep unk | awk ‘{print $1}’`; \
+        do; \
+          onevm restart $vm; \
+        done 
+
+After this, all of the VMs should return to the `running` state and
+again be accessible from the network.  Any machines that don't restart
+are probably lost and will have to be killed and a new instance
+created.
+