diff --git a/doc/src/sgml/backup.sgml b/doc/src/sgml/backup.sgml
index 854b5fd..d8286b0 100644
--- a/doc/src/sgml/backup.sgml
+++ b/doc/src/sgml/backup.sgml
@@ -448,6 +448,13 @@ tar -cf backup.tar /usr/local/pgsql/data
the contents of indexes for example, just the commands to recreate
them.) However, taking a file system backup might be faster.
+
+
+ When doing a file system backup, it is recommended to drop replication
+ slots (see ) before using
+ it as it is not guaranteed that the WAL files needed by a slot will be
+ kept on the newly-created node.
+
diff --git a/doc/src/sgml/ref/pg_basebackup.sgml b/doc/src/sgml/ref/pg_basebackup.sgml
index 6ce0c8c..b81ad8d 100644
--- a/doc/src/sgml/ref/pg_basebackup.sgml
+++ b/doc/src/sgml/ref/pg_basebackup.sgml
@@ -590,6 +590,13 @@ PostgreSQL documentation
or an older major version, down to 9.1. However, WAL streaming mode (-X
stream) only works with server version 9.3.
+
+
+ The backup will not include information about replication slots
+ (see ) as it is not
+ guaranteed that a node in recovery will have WAL files required for
+ a given slot.
+