are currently on by default. <xref linkend="guc-full-page-writes"/>

must also be set to <literal>on</literal>, but is enabled by default.

</para>

<warning>

<para>

If <application>pg_rewind</application> fails while processing, then

the data folder of the target is likely not in a state that can be

recovered. In such a case, taking a new fresh backup is recommended.

</para>

<para>

<application>pg_rewind</application> will fail immediately if it finds

files it cannot write directly to. This can happen for example when

the source and the target server use the same file mapping for read-only

SSL keys and certificates. If such files are present on the target server

it is recommended to remove them before running

<application>pg_rewind</application>. After doing the rewind, some of

those files may have been copied from the source, in which case it may

be necessary to remove the data copied and restore back the set of links

used before the rewind.

</para>

</warning>

</refsect1>

<refsect1>