Implement sync option

[nbd.git] / nbd-server.5.sgml

diff --git a/nbd-server.5.sgml b/nbd-server.5.sgml
index 47c65ee..fa9b321 100644 (file)
--- a/nbd-server.5.sgml
+++ b/nbd-server.5.sgml
@@ -329,6 +329,23 @@ manpage.1: manpage.sgml
        </listitem>
       </varlistentry>
       <varlistentry>
+        <term><option>sync</option></term>
+       <listitem>
+         <para>Optional; boolean.</para>
+         <para>When this option is enabled,
+           <command>nbd-server</command> will call an fsync() after every
+           write to the backend storage. Calling fsync() increases
+           reliability in case of an unclean shutdown of nbd-server; but,
+           depending on the file system used on the nbd-server side, may
+           degrade performance. The use of this option isn't always
+           necessary; e.g., on ext3 filesystems, it is recommended that
+           it is <emphasis>not</emphasis> enabled, since it seriously
+           reduces performance on ext3 filesystems while not
+           importantly impacting performance.
+         </para>
+       </listitem>
+      </varlistentry>
+      <varlistentry>
        <term><option>sparse_cow</option></term>
        <listitem>
          <para>Optional; boolean.</para>