From ed3fb7afa91bf274af36073583e4dcc15bb04be2 Mon Sep 17 00:00:00 2001
From: Tom Rhodes <trhodes@FreeBSD.org>
Date: Sun, 24 Nov 2002 21:33:22 +0000
Subject: [PATCH] Document a method for rebuilding ATA RAID1.  Tested on a
 HighPoint ATA controller with hot-swap.

Submitted by:	Roy Hooper <rhooper@cyberus.ca> (Original version)
---
 .../books/handbook/disks/chapter.sgml         | 88 +++++++++++++++++++
 1 file changed, 88 insertions(+)

diff --git a/en_US.ISO8859-1/books/handbook/disks/chapter.sgml b/en_US.ISO8859-1/books/handbook/disks/chapter.sgml
index a87654d2ca..b09d5d04a2 100644
--- a/en_US.ISO8859-1/books/handbook/disks/chapter.sgml
+++ b/en_US.ISO8859-1/books/handbook/disks/chapter.sgml
@@ -570,6 +570,94 @@ sh MAKEDEV ccd0</programlisting>
 	accordingly.
       </para>
     </sect2>
+    
+    <sect2>
+      <title>Rebuilding ATA RAID1 Arrays</title>
+
+      <para>FreeBSD allows you to hot-replace a failed disk in an array. This requires
+	that you catch it before you reboot.</para>
+
+      <para>You will probably see something like the following in the syslog/dmesg
+	output:</para>
+
+      <programlisting>ad6 on monster1 suffered a hard error.
+ad6: READ command timeout tag=0 serv=0 - resetting
+ad6: trying fallback to PIO mode
+ata3: resetting devices .. done
+ad6: hard error reading fsbn 1116119 of 0-7 (ad6 bn 1116119; cn 1107 tn 4 sn 11) status=59 error=40
+ar0: WARNING - mirror lost</programlisting>
+
+      <para>Using &man.atacontrol.8;, check to see how things look:</para>
+
+      <screen>&prompt.root; <userinput>atacontrol list</userinput></screen>
+
+<programlisting>ATA channel 0:
+	Master:      no device present
+	Slave:   acd0 &lt;HL-DT-ST CD-ROM GCR-8520B/1.00&gt; ATA/ATAPI rev 0
+
+ATA channel 1:
+	Master:      no device present
+	Slave:       no device present
+
+ATA channel 2:
+	Master:  ad4 &lt;MAXTOR 6L080J4/A93.0500&gt; ATA/ATAPI rev 5
+	Slave:       no device present
+
+ATA channel 3:
+	Master:  ad6 &lt;MAXTOR 6L080J4/A93.0500&gt; ATA/ATAPI rev 5
+	Slave:       no device present</programlisting>
+
+      <screen>&prompt.root; <userinput>atacontrol status ar0</userinput></screen>
+
+      <programlisting>ar0: ATA RAID1 subdisks: ad4 ad6 status: DEGRADED</programlisting>
+
+      <procedure>
+	<step>
+	  <para>You will first need to detach the disk from the array so that you can
+	    safely remove it:</para>
+
+	  <screen>&prompt.root; <userinput>atacontrol detach 3</userinput></screen>
+	</step>
+
+	<step>
+	  <para>Replace the disk.</para>
+	</step>
+
+	<step>
+	  <para>Reattach the disk as a spare:</para>
+
+	  <screen>&prompt.root; <userinput>atacontrol attach 3</userinput></screen>
+
+	  <programlisting>Master:  ad6 &lt;MAXTOR 6L080J4/A93.0500&gt; ATA/ATAPI rev 5
+Slave:   no device present</programlisting>
+
+	<step>
+	  <para>Rebuild the array:</para>
+
+	  <screen>&prompt.root; <userinput>atacontrol rebuild ar0</userinput></screen>
+	</step>
+
+	<step>
+	  <para>The rebuild command hangs until complete, its possible to open another
+	    terminal and check on the progress by issuing the following command:</para>
+
+	  <screen>&prompt.root; <userinput>dmesg | tail -10</userinput></screen>
+
+	  <programlisting>[output removed]
+ad6: removed from configuration
+ad6: deleted from ar0 disk1
+ad6: inserted into ar0 disk1 as spare</programlisting>
+
+	  <screen>&prompt.root; <userinput>atacontrol status ar0</userinput></screen>
+
+	  <programlisting>ar0: ATA RAID1 subdisks: ad4 ad6 status: REBUILDING 0% completed</programlisting>
+	</step>
+
+	<step>
+	  <para>Wait until this operation completes.</para>
+	</step>
+      </procedure>
+    </sect2>
   </sect1>
   
   <sect1 id="creating-cds">