diff --git a/doc/src/sgml/manage-ag.sgml b/doc/src/sgml/manage-ag.sgml
index b44d521ba6..78ec509a8b 100644
--- a/doc/src/sgml/manage-ag.sgml
+++ b/doc/src/sgml/manage-ag.sgml
@@ -379,17 +379,34 @@ dropdb dbname
expensive, slower disk system.
+
+
+ Even though located outside the main PostgreSQL data directory,
+ tablespaces are an integral part of the database cluster and
+ cannot be treated as an autonomous collection
+ of data files. They are dependent on metadata contained in the main
+ data directory, and therefore cannot be attached to a different
+ database cluster or backed up individually. Similarly, if you lose
+ a tablespace (file deletion, disk failure, etc), the database cluster
+ might become unreadable or unable to start. Placing a tablespace
+ on a temporary file system like a ramdisk risks the reliability of
+ the entire cluster.
+
+
+
To define a tablespace, use the
command, for example:CREATE TABLESPACE>>:
-CREATE TABLESPACE fastspace LOCATION '/mnt/sda1/postgresql/data';
+CREATE TABLESPACE fastspace LOCATION '/ssd1/postgresql/data';
The location must be an existing, empty directory that is owned by
the PostgreSQL> operating system user. All objects subsequently
created within the tablespace will be stored in files underneath this
- directory.
+ directory. The location must not be on removable or transient storage,
+ as the cluster might fail to function if the tablespace is missing
+ or lost.
diff --git a/doc/src/sgml/ref/create_tablespace.sgml b/doc/src/sgml/ref/create_tablespace.sgml
index b643565057..cf6215ee60 100644
--- a/doc/src/sgml/ref/create_tablespace.sgml
+++ b/doc/src/sgml/ref/create_tablespace.sgml
@@ -50,6 +50,14 @@ CREATE TABLESPACE tablespace_name
CREATE INDEX> or ADD CONSTRAINT> to have the data
files for these objects stored within the specified tablespace.
+
+
+
+ A tablespace cannot be used independently of the cluster in which it
+ is defined; see .
+
+
+