Attachment 36613 Details for Bug 58615 – file.diff

[patch] file.diff

file.diff (text/plain), 3.08 KB, created by Dmitry Morozovsky on 2003-10-28 12:00:34 UTC

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Creator: Dmitry Morozovsky

Created: 2003-10-28 12:00:34 UTC

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obsolete

>Index: chapter.sgml
>===================================================================
>RCS file: /home/ncvs/doc/en_US.ISO8859-1/books/handbook/vinum/chapter.sgml,v
>retrieving revision 1.24
>diff -u -r1.24 chapter.sgml
>--- chapter.sgml	31 Aug 2003 16:41:36 -0000	1.24
>+++ chapter.sgml	28 Oct 2003 11:51:27 -0000
>@@ -362,7 +362,7 @@
>     <sect2>
>       <title>Which Plex Organization?</title>
>       <para>The version of Vinum supplied with FreeBSD &rel.current; implements
>-	two kinds of plex:</para>
>+	three kinds of plex:</para>
>     
>       <itemizedlist>
> 	<listitem>
>@@ -386,11 +386,24 @@
> 	    (fractionally) more complex code and restrictions on
> 	    subdisks: they must be all the same size, and extending a
> 	    plex by adding new subdisks is so complicated that Vinum
>-	    currently does not implement it.  Vinum imposes an
>+	    currently does not implement it (actually, you have to reconstruct
>+	    file system after adding or removing subdisks to the underlying plex).  
>+	    Vinum imposes an
> 	    additional, trivial restriction: a striped plex must have
> 	    at least two subdisks, since otherwise it is
> 	    indistinguishable from a concatenated plex.</para>
> 	</listitem>
>+
>+	<listitem>
>+	  <para>raid5
>+	    plexes implement redundancy with low volume overhead for the price
>+	    of higher CPU load and relatively low write speed.  As for striped
>+	    plexes, subdisks involved must be the same size, and extending
>+	    raid5 plex will need its complete reformatting.  Minimal raid5 plex
>+	    must contain at least 3 subdisks; due to performance reasons, 5 or
>+	    more subdisks (all on different drives, of course) are
>+	    recommended.</para>
>+	</listitem>
>       </itemizedlist>
>     
>       <para><xref linkend="vinum-comparison"> summarizes the advantages
>@@ -427,6 +440,15 @@
> 	      <entry>High performance in combination with highly concurrent
> 		access</entry>
> 	    </row>
>+	    
>+	    <row>
>+	      <entry>radi5</entry>
>+	      <entry>3</entry>
>+	      <entry>no</entry>
>+	      <entry>yes</entry>
>+	      <entry>High read performance in combination with redundancy such
>+	        as large data archives</entry>
>+	    </row>
> 	  </tbody>
> 	</tgroup>
>       </table>
>@@ -708,6 +730,30 @@
> 	  <graphic fileref="vinum/vinum-raid10-vol">
>         </figure>
>       </para>
>+    </sect2>
>+
>+    <sect2>
>+      <title>Resilience and Performance: Hard Way</title>
>+
>+      <para><anchor id="vinum-raid5">With sufficient hardware and CPU power,
>+	especially when most of disc activities are reads, it would be useful
>+	to make raid5 volume, which consumes only 1/n of disk volume for
>+	resilience instead of 1/2 for mirrored volumes, and still achieves
>+	great read performance.  A typical configuration file might
>+	be:</para>
>+
>+      <programlisting>
>+	volume raid5
>+      plex org raid5 512k
>+        sd length 102480k drive a
>+        sd length 102480k drive b
>+        sd length 102480k drive c
>+        sd length 102480k drive d
>+        sd length 102480k drive e</programlisting>
>+
>+      <para>Note we have single plex here because raid5 provides
>+	fault-tolerance itself.</para>
>+
>     </sect2>
>   </sect1>

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