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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta name="generator" content="HTML Tidy, see www.w3.org" /><title>Some Examples</title><meta name="GENERATOR" content="Modular DocBook HTML Stylesheet Version 1.7" /><link rel="HOME" title="FreeBSD 使用手册" href="index.html" /><link rel="UP" title="The Vinum Volume Manager" href="vinum-vinum.html" /><link rel="PREVIOUS" title="Vinum Objects" href="vinum-objects.html" /><link rel="NEXT" title="Object Naming" href="vinum-object-naming.html" /><link rel="STYLESHEET" type="text/css" href="docbook.css" /><meta http-equiv="Content-Type" content="text/html; charset=GB2312" /></head><body class="SECT1" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#840084"alink="#0000FF"><div class="NAVHEADER"><table summary="Header navigation table" width="100%" border="0" cellpadding="0"cellspacing="0"><tr><th colspan="3" align="center">FreeBSD 使用手册</th></tr><tr><td width="10%" align="left" valign="bottom"><a href="vinum-objects.html"accesskey="P">Prev</a></td><td width="80%" align="center" valign="bottom">Chapter 13. The Vinum Volume Manager</td><td width="10%" align="right" valign="bottom"><a href="vinum-object-naming.html"accesskey="N">Next</a></td></tr></table><hr align="LEFT" width="100%" /></div><div class="SECT1"><h1 class="SECT1"><a id="VINUM-EXAMPLES" name="VINUM-EXAMPLES">13.6. SomeExamples</a></h1><p>Vinum maintains a <span class="emphasis"><i class="EMPHASIS">configurationdatabase</i></span> which describes the objects known to an individual system. Initially,the user creates the configuration database from one or more configuration files with theaid of the <span class="CITEREFENTRY"><span class="REFENTRYTITLE">vinum</span>(8)</span>utility program. Vinum stores a copy of its configuration database on each disk slice(which Vinum calls a <span class="emphasis"><i class="EMPHASIS">device</i></span>) underits control. This database is updated on each state change, so that a restart accuratelyrestores the state of each Vinum object.</p><div class="SECT2"><h2 class="SECT2"><a id="AEN18965" name="AEN18965">13.6.1. The ConfigurationFile</a></h2><p>The configuration file describes individual Vinum objects. The definition of a simplevolume might be:</p><pre class="PROGRAMLISTING"> drive a device /dev/da3h volume myvol plex org concat sd length 512m drive a</pre><p>This file describes four Vinum objects:</p><ul><li><p>The <span class="emphasis"><i class="EMPHASIS">drive</i></span> line describes a diskpartition (<span class="emphasis"><i class="EMPHASIS">drive</i></span>) and its locationrelative to the underlying hardware. It is given the symbolic name <spanclass="emphasis"><i class="EMPHASIS">a</i></span>. This separation of the symbolic namesfrom the device names allows disks to be moved from one location to another withoutconfusion.</p></li><li><p>The <span class="emphasis"><i class="EMPHASIS">volume</i></span> line describes avolume. The only required attribute is the name, in this case <span class="emphasis"><iclass="EMPHASIS">myvol</i></span>.</p></li><li><p>The <span class="emphasis"><i class="EMPHASIS">plex</i></span> line defines a plex.The only required parameter is the organization, in this case <span class="emphasis"><iclass="EMPHASIS">concat</i></span>. No name is necessary: the system automaticallygenerates a name from the volume name by adding the suffix <span class="emphasis"><iclass="EMPHASIS">.p</i></span><span class="emphasis"><i class="EMPHASIS">x</i></span>,where <span class="emphasis"><i class="EMPHASIS">x</i></span> is the number of the plexin the volume. Thus this plex will be called <span class="emphasis"><iclass="EMPHASIS">myvol.p0</i></span>.</p></li><li><p>The <span class="emphasis"><i class="EMPHASIS">sd</i></span> line describes a subdisk.The minimum specifications are the name of a drive on which to store it, and the lengthof the subdisk. As with plexes, no name is necessary: the system automatically assignsnames derived from the plex name by adding the suffix <span class="emphasis"><iclass="EMPHASIS">.s</i></span><span class="emphasis"><i class="EMPHASIS">x</i></span>,where <span class="emphasis"><i class="EMPHASIS">x</i></span> is the number of thesubdisk in the plex. Thus Vinum gives this subdisk the name <span class="emphasis"><iclass="EMPHASIS">myvol.p0.s0</i></span>.</p></li></ul><p>After processing this file, <span class="CITEREFENTRY"><spanclass="REFENTRYTITLE">vinum</span>(8)</span> produces the following output:</p><pre class="PROGRAMLISTING"> <samp class="PROMPT">#</samp> vinum -> <tt class="COMMAND">create config1</tt> Configuration summary Drives: 1 (4 configured) Volumes: 1 (4 configured) Plexes: 1 (8 configured) Subdisks: 1 (16 configured) D a State: up Device /dev/da3h Avail: 2061/2573 MB (80%) V myvol State: up Plexes: 1 Size: 512 MB P myvol.p0 C State: up Subdisks: 1 Size: 512 MB S myvol.p0.s0 State: up PO: 0 B Size: 512 MB</pre><p>This output shows the brief listing format of <span class="CITEREFENTRY"><spanclass="REFENTRYTITLE">vinum</span>(8)</span>. It is represented graphically in <ahref="vinum-examples.html#VINUM-SIMPLE-VOL">Figure 13-4</a>.</p><p></p><div class="FIGURE"><a id="VINUM-SIMPLE-VOL" name="VINUM-SIMPLE-VOL"></a><p><b>Figure 13-4. A Simple Vinum Volume</b></p><p><img src="vinum/vinum-simple-vol.png" /></p></div><br /><br /><p>This figure, and the ones which follow, represent a volume, which contains the plexes,which in turn contain the subdisks. In this trivial example, the volume contains oneplex, and the plex contains one subdisk.</p><p>This particular volume has no specific advantage over a conventional disk partition.It contains a single plex, so it is not redundant. The plex contains a single subdisk, sothere is no difference in storage allocation from a conventional disk partition. Thefollowing sections illustrate various more interesting configuration methods.</p></div><div class="SECT2"><h2 class="SECT2"><a id="AEN19013" name="AEN19013">13.6.2. Increased Resilience:Mirroring</a></h2><p>The resilience of a volume can be increased by mirroring. When laying out a mirroredvolume, it is important to ensure that the subdisks of each plex are on different drives,so that a drive failure will not take down both plexes. The following configurationmirrors a volume:</p><pre class="PROGRAMLISTING"> drive b device /dev/da4h volume mirror plex org concat sd length 512m drive a plex org concat sd length 512m drive b</pre><p>In this example, it was not necessary to specify a definition of drive <spanclass="emphasis"><i class="EMPHASIS">a</i></span> again, since Vinum keeps track of allobjects in its configuration database. After processing this definition, theconfiguration looks like:</p><pre class="PROGRAMLISTING"> Drives: 2 (4 configured) Volumes: 2 (4 configured) Plexes: 3 (8 configured) Subdisks: 3 (16 configured) D a State: up Device /dev/da3h Avail: 1549/2573 MB (60%) D b State: up Device /dev/da4h Avail: 2061/2573 MB (80%) V myvol State: up Plexes: 1 Size: 512 MB V mirror State: up Plexes: 2 Size: 512 MB P myvol.p0 C State: up Subdisks: 1 Size: 512 MB P mirror.p0 C State: up Subdisks: 1 Size: 512 MB P mirror.p1 C State: initializing Subdisks: 1 Size: 512 MB S myvol.p0.s0 State: up PO: 0 B Size: 512 MB S mirror.p0.s0 State: up PO: 0 B Size: 512 MB S mirror.p1.s0 State: empty PO: 0 B Size: 512 MB</pre><p><a href="vinum-examples.html#VINUM-MIRRORED-VOL">Figure 13-5</a> shows the structuregraphically.</p><p></p><div class="FIGURE"><a id="VINUM-MIRRORED-VOL" name="VINUM-MIRRORED-VOL"></a><p><b>Figure 13-5. A Mirrored Vinum Volume</b></p><p><img src="vinum/vinum-mirrored-vol.png" /></p></div><br /><br /><p>In this example, each plex contains the full 512 MB of address space. As in theprevious example, each plex contains only a single subdisk.</p></div><div class="SECT2"><h2 class="SECT2"><a id="AEN19027" name="AEN19027">13.6.3. OptimizingPerformance</a></h2><p>The mirrored volume in the previous example is more resistant to failure than anunmirrored volume, but its performance is less: each write to the volume requires a writeto both drives, using up a greater proportion of the total disk bandwidth. Performanceconsiderations demand a different approach: instead of mirroring, the data is stripedacross as many disk drives as possible. The following configuration shows a volume with aplex striped across four disk drives:</p><pre class="PROGRAMLISTING"> drive c device /dev/da5h drive d device /dev/da6h volume stripe plex org striped 512k sd length 128m drive a sd length 128m drive b sd length 128m drive c sd length 128m drive d</pre><p>As before, it is not necessary to define the drives which are already known to Vinum.After processing this definition, the configuration looks like:</p><pre class="PROGRAMLISTING"> Drives: 4 (4 configured) Volumes: 3 (4 configured) Plexes: 4 (8 configured) Subdisks: 7 (16 configured) D a State: up Device /dev/da3h Avail: 1421/2573 MB (55%) D b State: up Device /dev/da4h Avail: 1933/2573 MB (75%) D c State: up Device /dev/da5h Avail: 2445/2573 MB (95%) D d State: up Device /dev/da6h Avail: 2445/2573 MB (95%) V myvol State: up Plexes: 1 Size: 512 MB V mirror State: up Plexes: 2 Size: 512 MB V striped State: up Plexes: 1 Size: 512 MB P myvol.p0 C State: up Subdisks: 1 Size: 512 MB P mirror.p0 C State: up Subdisks: 1 Size: 512 MB P mirror.p1 C State: initializing Subdisks: 1 Size: 512 MB P striped.p1 State: up Subdisks: 1 Size: 512 MB S myvol.p0.s0 State: up PO: 0 B Size: 512 MB S mirror.p0.s0 State: up PO: 0 B Size: 512 MB S mirror.p1.s0 State: empty PO: 0 B Size: 512 MB S striped.p0.s0 State: up PO: 0 B Size: 128 MB S striped.p0.s1 State: up PO: 512 kB Size: 128 MB S striped.p0.s2 State: up PO: 1024 kB Size: 128 MB S striped.p0.s3 State: up PO: 1536 kB Size: 128 MB</pre><p></p><div class="FIGURE"><a id="VINUM-STRIPED-VOL" name="VINUM-STRIPED-VOL"></a><p><b>Figure 13-6. A Striped Vinum Volume</b></p><p><img src="vinum/vinum-striped-vol.png" /></p></div><br /><br /><p>This volume is represented in <a href="vinum-examples.html#VINUM-STRIPED-VOL">Figure13-6</a>. The darkness of the stripes indicates the position within the plex addressspace: the lightest stripes come first, the darkest last.</p></div><div class="SECT2"><h2 class="SECT2"><a id="AEN19039" name="AEN19039">13.6.4. Resilience andPerformance</a></h2><p><a id="VINUM-RESILIENCE" name="VINUM-RESILIENCE"></a>With sufficient hardware, it ispossible to build volumes which show both increased resilience and increased performancecompared to standard <span class="TRADEMARK">UNIX</span>® partitions. A typicalconfiguration file might be:</p><pre class="PROGRAMLISTING"> volume raid10 plex org striped 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 plex org striped 512k sd length 102480k drive c sd length 102480k drive d sd length 102480k drive e sd length 102480k drive a sd length 102480k drive b</pre><p>The subdisks of the second plex are offset by two drives from those of the first plex:this helps ensure that writes do not go to the same subdisks even if a transfer goes overtwo drives.</p><p><a href="vinum-examples.html#VINUM-RAID10-VOL">Figure 13-7</a> represents thestructure of this volume.</p><p></p><div class="FIGURE"><a id="VINUM-RAID10-VOL" name="VINUM-RAID10-VOL"></a><p><b>Figure 13-7. A Mirrored, Striped Vinum Volume</b></p><p><img src="vinum/vinum-raid10-vol.png" /></p></div><br /><br /></div></div><div class="NAVFOOTER"><hr align="LEFT" width="100%" /><table summary="Footer navigation table" width="100%" border="0" cellpadding="0"cellspacing="0"><tr><td width="33%" align="left" valign="top"><a href="vinum-objects.html"accesskey="P">Prev</a></td><td width="34%" align="center" valign="top"><a href="index.html"accesskey="H">Home</a></td><td width="33%" align="right" valign="top"><a href="vinum-object-naming.html"accesskey="N">Next</a></td></tr><tr><td width="33%" align="left" valign="top">Vinum Objects</td><td width="34%" align="center" valign="top"><a href="vinum-vinum.html"accesskey="U">Up</a></td><td width="33%" align="right" valign="top">Object Naming</td></tr></table></div></body></html>⌨️ 快捷键说明
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