doc: document rank option for journal reset

Signed-off-by: Patrick Donnelly <pdonnell@redhat.com>

diff --git a/doc/cephfs/disaster-recovery-experts.rst b/doc/cephfs/disaster-recovery-experts.rst
index 47c7bd9bfc05f41b34e9e2fdf754d64780d106ee..1b0087bfaa818f182b9cdfaa31e781dd6d66ae3a 100644 (file)
--- a/doc/cephfs/disaster-recovery-experts.rst
+++ b/doc/cephfs/disaster-recovery-experts.rst
@@ -68,7 +68,10 @@ truncate it like so:
 
 ::
 
-    cephfs-journal-tool journal reset
+    cephfs-journal-tool [--rank=N] journal reset
+
+Specify the MDS rank using the ``--rank`` option when the file system has/had
+multiple active MDS.
 
 .. warning::