doc: clarify availability vs integrity

(cherry picked from commit 3888cf77075eceb079b1d5a8ce19092d12fd82bd)

diff --git a/doc/architecture.rst b/doc/architecture.rst
index d38445067e40f761603faeabf997cc3e3ea8f369..310064962703539eea4706a924131d0db439c426 100644 (file)
--- a/doc/architecture.rst
+++ b/doc/architecture.rst
@@ -739,7 +739,8 @@ of ``K+M`` so that each chunk is stored in an OSD in the acting set. The rank of
 the chunk is stored as an attribute of the object.
 
 For instance an erasure coded pool can be created to use five OSDs (``K+M = 5``) and
-sustain the loss of two of them (``M = 2``).
+sustain the loss of two of them (``M = 2``). Data may be unavailable until (``K+1``)
+shards are restored.
 
 Reading and Writing Encoded Chunks
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~