Doc: Add config option to turn off crush update

Signed-off-by: David Moreau Simard <dmsimard@iweb.com>

diff --git a/doc/rados/operations/crush-map.rst b/doc/rados/operations/crush-map.rst
index 7328865dfe6c9e35262c6df64c0e92741e7b82ba..01c48d450258650fad7c6839156909fece9838cc 100644 (file)
--- a/doc/rados/operations/crush-map.rst
+++ b/doc/rados/operations/crush-map.rst
@@ -80,8 +80,9 @@ Note:
 ceph-crush-location hook
 ------------------------
 
-The ``ceph-crush-location`` utility will generate a default CRUSH location
-string for a given daemon.  The location is based on, in order of preference:
+By default, the ``ceph-crush-location`` utility will generate a CRUSH
+location string for a given daemon.  The location is based on, in order of
+preference:
 
 #. A ``TYPE crush location`` option in ceph.conf.  For example, this
    is ``osd crush location`` for OSD daemons.
@@ -95,6 +96,11 @@ ceph.conf to describe that machine's location within the datacenter or
 cluster.  This will be provide location awareness to both Ceph daemons
 and clients alike.
 
+It is possible to manage the CRUSH map entirely manually by toggling
+the hook off in the configuration::
+
+  osd crush update on start = false
+
 Custom location hooks
 ---------------------