librbd: clarify rbd_read_from_replica_policy vs older options

If rbd_read_from_replica_policy is set appropriately, setting
rbd_balance/localize_snap_reads or rbd_balance/localize_parent_reads
is redundant.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

diff --git a/src/common/options/rbd.yaml.in b/src/common/options/rbd.yaml.in
index e7b2f2e6048d9cb0fe1ed58585e604f399461cbc..14c782df9662c045ec51b8c1e4bd8ce8eceeb6a3 100644 (file)
--- a/src/common/options/rbd.yaml.in
+++ b/src/common/options/rbd.yaml.in
@@ -206,6 +206,8 @@ options:
   default: false
   services:
   - rbd
+  see_also:
+  - rbd_read_from_replica_policy
 - name: rbd_localize_snap_reads
   type: bool
   level: advanced
@@ -213,6 +215,8 @@ options:
   default: false
   services:
   - rbd
+  see_also:
+  - rbd_read_from_replica_policy
 - name: rbd_balance_parent_reads
   type: bool
   level: advanced
@@ -220,6 +224,8 @@ options:
   default: false
   services:
   - rbd
+  see_also:
+  - rbd_read_from_replica_policy
 - name: rbd_localize_parent_reads
   type: bool
   level: advanced
@@ -227,6 +233,8 @@ options:
   default: false
   services:
   - rbd
+  see_also:
+  - rbd_read_from_replica_policy
 - name: rbd_sparse_read_threshold_bytes
   type: size
   level: advanced
@@ -355,9 +363,11 @@ options:
     for read operations. If set to ``balance``, read operations will
     be sent to a randomly selected OSD within the replica set. If set
     to ``localize``, read operations will be sent to the closest OSD
-    as determined by the CRUSH map. Note: this feature requires the
-    cluster to be configured with a minimum compatible OSD release of
-    Octopus.
+    as determined by the CRUSH map. Unlike ``rbd_balance_snap_reads``
+    and ``rbd_localize_snap_reads`` or ``rbd_balance_parent_reads`` and
+    ``rbd_localize_parent_reads``, it affects all read operations, not
+    just snap or parent. Note: this feature requires the cluster to
+    be configured with a minimum compatible OSD release of Octopus.
   default: default
   services:
   - rbd