mds: warn for mds_cache_memory_limit bug in doc

Fixes: http://tracker.ceph.com/issues/22599
Signed-off-by: Patrick Donnelly <pdonnell@redhat.com>

diff --git a/doc/_themes/ceph/static/nature.css_t b/doc/_themes/ceph/static/nature.css_t
index 71fb56f4d918fb0eba203a451ad1ed14083dd7cb..95813cb022fa7c1770c9069dc744a7444e4823f9 100644 (file)
--- a/doc/_themes/ceph/static/nature.css_t
+++ b/doc/_themes/ceph/static/nature.css_t
@@ -219,6 +219,10 @@ div.warning {
     border: 1px solid #9C4850;
     color: #fff;
 }
+
+div.warning a {
+    color: black;
+}
  
 p.admonition-title {
     display: inline;

diff --git a/doc/cephfs/cache-size-limits.rst b/doc/cephfs/cache-size-limits.rst
index 4ea41443bcd5719d761a8e232446cf3cfc85271d..90cf8ade76091604a1156db98b1dba63e57d5a79 100644 (file)
--- a/doc/cephfs/cache-size-limits.rst
+++ b/doc/cephfs/cache-size-limits.rst
@@ -13,3 +13,10 @@ In addition, you can specify a cache reservation by using the `mds_cache_reserva
 The `mds_cache_reservation` parameter replaces the `mds_health_cache_threshold` in all situations except when MDS nodes sends a health alert to the Monitors indicating the cache is too large. By default, `mds_health_cache_threshold` is 150% of the maximum cache size.
 
 Be aware that the cache limit is not a hard limit. Potential bugs in the CephFS client or MDS or misbehaving applications might cause the MDS to exceed its cache size. The  `mds_health_cache_threshold` configures the cluster health warning message so that operators can investigate why the MDS cannot shrink its cache.
+
+.. warning::
+
+    The memory tracking used is currently imprecise by a constant factor. This
+    will be addressed in http://tracker.ceph.com/issues/22599. MDS deployments
+    with large `mds_cache_memory_limit` (64GB+) should underallocate RAM to
+    accomodate.