ch9.htm

汤子瀛《操作系统》电子教案

      <p style="TEXT-INDENT: 18pt"><font color="#FFFFFF"><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">空闲盘块的组织</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p style="TEXT-INDENT: 18pt"><font color="#FFFFFF"><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">空闲盘块的分配与回收</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
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      <p style="TEXT-ALIGN: center" align="center"><font color="#FFFFFF"><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><a name="ch94"></a>9</span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">．</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt">4<span style="mso-spacerun: yes">&nbsp; 
      </span></span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">磁盘容错技术</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p><font color="#FFFFFF"><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">磁盘容错技术：</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p><font color="#FFFFFF"><span lang="EN-US" style="mso-bidi-font-size: 10.0pt">SFT-1</span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">：低级磁盘容错技术，主要用于防止磁盘表面仿生缺陷所引起的数据丢失；</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p><font color="#FFFFFF"><span lang="EN-US" style="mso-bidi-font-size: 10.0pt">SFT-2</span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">：中级磁盘容错技术，主要用于防止磁盘驱动器和磁盘控制器故障引起的系统不能正常工作；</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p><font color="#FFFFFF"><span lang="EN-US" style="mso-bidi-font-size: 10.0pt">SFT-3</span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">：高级磁盘容错技术。</span></font></p>
      <p style="MARGIN-LEFT: 18pt; TEXT-INDENT: -18pt; tab-stops: list 18.0pt; mso-list: l33 level1 lfo32"><font color="#FFFFFF"><span lang="EN-US" style="mso-fareast-font-family: 黑体">1．</span><span style="mso-ascii-font-family: Times New Roman">第一级容错技术</span><span lang="EN-US" style="mso-fareast-font-family: 黑体"><o:p>
      </o:p>
      </span></font></p>
      <p style="MARGIN-LEFT: 18pt"><font color="#FFFFFF"><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">⑴双份目录和双份文件分配表</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p style="MARGIN-LEFT: 18pt"><font color="#FFFFFF"><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">⑵热修复重定向和写后读校验：</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p style="MARGIN-LEFT: 18pt"><font color="#FFFFFF"><span style="mso-spacerun: yes; mso-bidi-font-size: 10.0pt" lang="EN-US">&nbsp; 
      </span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">热修复重定向：</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p style="MARGIN-LEFT: 18pt"><font color="#FFFFFF"><span style="mso-spacerun: yes; mso-bidi-font-size: 10.0pt" lang="EN-US">&nbsp; 
      </span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">写后读校验：</span></font></p>
      <p><span lang="EN-US"><font color="#FFFFFF">2．第二级容错技术<o:p>
      </o:p>
      </font></span></p>
      <p><font color="#FFFFFF"><span style="mso-spacerun: yes" lang="EN-US">&nbsp; 
      </span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">⑴磁盘镜像</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p><font color="#FFFFFF"><span style="mso-spacerun: yes; mso-bidi-font-size: 10.0pt" lang="EN-US">&nbsp; 
      </span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">⑵磁盘双工</span></font></p>
      <p><span lang="EN-US"><font color="#FFFFFF">3．廉价磁盘冗余阵列<o:p>
      </o:p>
      </font></span></p>
      <p><font color="#FFFFFF"><span style="mso-spacerun: yes" lang="EN-US">&nbsp; 
      </span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">⑴并行交叉存取</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p><font color="#FFFFFF"><span style="mso-spacerun: yes; mso-bidi-font-size: 10.0pt" lang="EN-US">&nbsp; 
      </span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">⑵</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt">RAID</span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">分级</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p><font color="#FFFFFF"><span style="mso-spacerun: yes; mso-bidi-font-size: 10.0pt" lang="EN-US">&nbsp; 
      </span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">⑶</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt">RAID</span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">的优点</span></font></p>
      <p><span lang="EN-US"><font color="#FFFFFF">4．后备系统<o:p>
      </o:p>
      </font></span></p>
      <p><font color="#FFFFFF"><span style="mso-spacerun: yes" lang="EN-US">&nbsp; 
      </span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">⑴后备系统的类型</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p><font color="#FFFFFF"><span style="mso-spacerun: yes; mso-bidi-font-size: 10.0pt" lang="EN-US">&nbsp;&nbsp; 
      </span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">磁带机：</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p><font color="#FFFFFF"><span style="mso-spacerun: yes; mso-bidi-font-size: 10.0pt" lang="EN-US">&nbsp;&nbsp; 
      </span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">硬盘：</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p><font color="#FFFFFF"><span style="mso-spacerun: yes; mso-bidi-font-size: 10.0pt" lang="EN-US">&nbsp;&nbsp; 
      </span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">光盘：</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p><font color="#FFFFFF"><span style="mso-spacerun: yes; mso-bidi-font-size: 10.0pt" lang="EN-US">&nbsp; 
      </span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">⑵拷贝方法：</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p><font color="#FFFFFF"><span style="mso-spacerun: yes; mso-bidi-font-size: 10.0pt" lang="EN-US">&nbsp;&nbsp; 
      </span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">完全转储：</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p><font color="#FFFFFF"><span style="mso-spacerun: yes; mso-bidi-font-size: 10.0pt" lang="EN-US">&nbsp;&nbsp; 
      </span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">增量转储：</span></font></p>
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      <p style="TEXT-ALIGN: center" align="center"><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><font color="#FFFFFF"><a name="ch95"></a>9．5<span style="mso-spacerun: yes">&nbsp; 
      </span>文件系统的性能改善<o:p>
      </o:p>
      </font></span></p>
      <p><font color="#FFFFFF"><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">提高对文件的访问速度：</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p><font color="#FFFFFF"><span style="mso-spacerun: yes; mso-bidi-font-size: 10.0pt" lang="EN-US">&nbsp;</span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">⑴改进文件的目录结构以及检索目录的方法，来减少对文件的查找时间；</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p><font color="#FFFFFF"><span style="mso-spacerun: yes; mso-bidi-font-size: 10.0pt" lang="EN-US">&nbsp;</span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">⑵选择好的文件存储结构，以提高对文件的访问速度；</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>
      </span></font></p>
      <p><font color="#FFFFFF"><span style="mso-spacerun: yes; mso-bidi-font-size: 10.0pt" lang="EN-US">&nbsp;</span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">⑶提高磁盘</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt">I/O</span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">速度，以提高对数据的传送速度。</span></font></p>
      <p style="MARGIN-LEFT: 18pt; TEXT-INDENT: -18pt; tab-stops: list 18.0pt; mso-list: l16 level1 lfo33"><font color="#FFFFFF"><span lang="EN-US" style="mso-fareast-font-family: 黑体">1．</span><span style="mso-ascii-font-family: Times New Roman">磁盘高速缓存</span><span lang="EN-US" style="mso-fareast-font-family: 黑体"><o:p>
      </o:p>
      </span></font></p>
      <p><font color="#FFFFFF"><span style="mso-spacerun: yes" lang="EN-US">&nbsp; 
      </span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">⑴磁盘高速缓存的形式——指利用内存中的存储空间，来暂存从磁盘中读出的一系列盘</span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">块中的信息。</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
      </o:p>