Subject: FFS soft-dependencies in chap-boot?
To: None <netbsd-docs@netbsd.org>
From: Daniel de Kok <daniel@netbsd.org>
List: netbsd-docs
Date: 01/14/2004 17:32:50
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Hi all,

In my humble opinion it would be a good idea to add some short information
about soft-dependencies to chap-boot. I have attached a short diff which
adds it.

Any comments?

With kind regards,
Daniel de Kok

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Index: chap-boot.xml
===================================================================
RCS file: /cvsroot/htdocs/guide/en/chap-boot.xml,v
retrieving revision 1.8
diff -b -u -r1.8 chap-boot.xml
--- chap-boot.xml	10 Jan 2004 22:04:47 -0000	1.8
+++ chap-boot.xml	14 Jan 2004 16:29:49 -0000
@@ -405,6 +405,47 @@
   <!-- ============================================================= -->
 
   <sect1>
+    <title>Enabling FFS soft-dependencies</title>
+
+    <para>
+      This might be a good point to enable soft-dependencies for FFS 
+      filesystems. By default FFS filesystems are mounted synchronously, which
+      means that meta-data is written away immediately. Soft-dependencies is a
+      mechanism which does not write away meta-data immediately, but it
+      is written in an ordered fashion, which keeps the filesystem consistent.
+      This provides performance comparable to asynchronous mounts, without 
+      the same risks. Soft-dependencies can be enabled by adding
+      <varname>softdep</varname> to the filesystem options in
+      <filename>/etc/fstab</filename>. Let's look at an example of
+      <filename>/etc/fstab</filename>:
+    </para>
+
+    <screen>
+/dev/wd0a / ffs rw 1 1
+/dev/wd0b none swap sw 0 0
+/dev/wd0e /var ffs rw 1 2
+/dev/wd0f /tmp ffs rw 1 2
+/dev/wd0g /usr ffs rw 1 2
+    </screen>
+
+    <para>
+      Suppose we want to enable soft-dependencies for all filesystems,
+      except for the <filename>/</filename> partition, we would change
+      it to (changes are emphasized):
+    </para>
+
+    <screen>
+/dev/wd0a / ffs rw 1 1
+/dev/wd0b none swap sw 0 0
+/dev/wd0e /var ffs rw<emphasis>,softdep</emphasis> 1 2
+/dev/wd0f /tmp ffs rw<emphasis>,softdep</emphasis> 1 2
+/dev/wd0g /usr ffs rw<emphasis>,softdep</emphasis> 1 2
+    </screen>
+  </sect1>
+
+  <!-- ============================================================= -->
+
+  <sect1>
     <title>Rebooting the system</title>
 
     <para>In this first session you have</para>

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