doc: 2 words about radosgw failures

- restarting the daemon.
- using the admin socket

Signed-off-by: Sage Weil <sage@newdream.net>

diff --git a/doc/ops/manage/failures/radosgw.rst b/doc/ops/manage/failures/radosgw.rst
index 2c16dd03a9a2dbb3a4287f6f959852ab0c3a4c04..6951fe8757115d51656fd5bee3144be9ccdeb480 100644 (file)
--- a/doc/ops/manage/failures/radosgw.rst
+++ b/doc/ops/manage/failures/radosgw.rst
@@ -2,3 +2,50 @@
  Recovering from radosgw failure
 =================================
 
+
+HTTP request errors
+===================
+
+Examining the access and error logs for the web server itself is
+probably the first step in identifying what is going on.  If there is
+a 500 error, that usually indicates a problem communicating with the
+radosgw daemon.  Ensure the daemon is running, it's socket path is
+configured, and that the web server is looking for it in the proper
+location.
+
+
+Crashed radosgw process
+=======================
+
+If the ``radosgw`` process dies, you will normally see a 500 error
+from the web server (apache, nginx, etc.).  In that situation, simply
+restarting radosgw will restore service.
+
+To diagnose the cause of the crash, check the log in ``/var/log/ceph``
+and/or the core file (if one was generated).
+
+
+Blocked radosgw requests
+========================
+
+If some (or all) radosgw requests appear to be blocked, you can get
+some insight into the internal state of the ``radosgw`` daemon via
+it's admin socket.  By default, there will be a socket configured to
+reside in ``/var/run/ceph``, and the daemon can be queried with::
+
+ $ ceph --admin-daemon /var/run/ceph/client.rgw help
+ help                list available commands
+ objecter_requests   show in-progress osd requests
+ perfcounters_dump   dump perfcounters value
+ perfcounters_schema dump perfcounters schema
+ version             get protocol version
+
+Of particular interest::
+
+ $ ceph --admin-daemon /var/run/ceph/client.rgw objecter_requests
+ ...
+
+will dump information about current in-progress requests with the
+RADOS cluster, which allow one to identify if a request is blocked
+by a non-responsive backend cluster.
+