fat+-+

FAT文件系统原理,硬盘结构及其分区简介

  "\000B";color:#3B3B3B'>部分</span><span lang=EN-US style='font-size:9.0pt;
  font-family:"\000B";color:#3B3B3B'>)</span><span style='font-size:9.0pt;
  mso-ascii-font-family:"\000B";mso-hansi-font-family:"\000B";color:#3B3B3B'>。引导扇区</span><span
  lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'>(DBR)</span><span
  style='font-size:9.0pt;mso-ascii-font-family:"\000B";mso-hansi-font-family:
  "\000B";color:#3B3B3B'>我们已经说过</span><span lang=EN-US style='font-size:9.0pt;
  font-family:"\000B";color:#3B3B3B'>,FAT16</span><span style='font-size:9.0pt;
  mso-ascii-font-family:"\000B";mso-hansi-font-family:"\000B";color:#3B3B3B'>在</span><span
  lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'>DBR</span><span
  style='font-size:9.0pt;mso-ascii-font-family:"\000B";mso-hansi-font-family:
  "\000B";color:#3B3B3B'>之后没有留有任何保留扇区，其后紧随的便是</span><span lang=EN-US
  style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'>FAT</span><span
  style='font-size:9.0pt;mso-ascii-font-family:"\000B";mso-hansi-font-family:
  "\000B";color:#3B3B3B'>表。</span><span lang=EN-US style='font-size:9.0pt;
  font-family:"\000B";color:#3B3B3B'>FAT</span><span style='font-size:9.0pt;
  mso-ascii-font-family:"\000B";mso-hansi-font-family:"\000B";color:#3B3B3B'>表是</span><span
  lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'>FAT16</span><span
  style='font-size:9.0pt;mso-ascii-font-family:"\000B";mso-hansi-font-family:
  "\000B";color:#3B3B3B'>用来记录磁盘数据区簇链结构的。像前面我们说过的例子一样，</span><span lang=EN-US
  style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'>FAT</span><span
  style='font-size:9.0pt;mso-ascii-font-family:"\000B";mso-hansi-font-family:
  "\000B";color:#3B3B3B'>将磁盘空间按一定数目的扇区为单位进行划分，这样的单位称为簇。通常情况下，每扇区</span><span
  lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'>512</span><span
  style='font-size:9.0pt;mso-ascii-font-family:"\000B";mso-hansi-font-family:
  "\000B";color:#3B3B3B'>字节的原则是不变的。簇的大小一般是</span><span lang=EN-US
  style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'>2<sup>n</sup> (n</span><span
  style='font-size:9.0pt;mso-ascii-font-family:"\000B";mso-hansi-font-family:
  "\000B";color:#3B3B3B'>为整数</span><span lang=EN-US style='font-size:9.0pt;
  font-family:"\000B";color:#3B3B3B'>)</span><span style='font-size:9.0pt;
  mso-ascii-font-family:"\000B";mso-hansi-font-family:"\000B";color:#3B3B3B'>个扇区的大小，像</span><span
  lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'>512B,1K,2K,4K,8K,16K,32K</span><span
  style='font-size:9.0pt;mso-ascii-font-family:"\000B";mso-hansi-font-family:
  "\000B";color:#3B3B3B'>，</span><span lang=EN-US style='font-size:9.0pt;
  font-family:"\000B";color:#3B3B3B'>64K</span><span style='font-size:9.0pt;
  mso-ascii-font-family:"\000B";mso-hansi-font-family:"\000B";color:#3B3B3B'>。实际中通常不超过</span><span
  lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'>32K</span><span
  style='font-size:9.0pt;mso-ascii-font-family:"\000B";mso-hansi-font-family:
  "\000B";color:#3B3B3B'>。</span><span style='font-size:9.0pt;font-family:
  "\000B";color:#3B3B3B'> </span><span style='font-size:9.0pt;mso-ascii-font-family:
  "\000B";mso-hansi-font-family:"\000B";color:#3B3B3B'>之所以簇为单位而不以扇区为单位进行磁盘的分配，是因为当分区容量较大时，采用大小为</span><span
  lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'>512b</span><span
  style='font-size:9.0pt;mso-ascii-font-family:"\000B";mso-hansi-font-family:
  "\000B";color:#3B3B3B'>的扇区管理会增加</span><span lang=EN-US style='font-size:
  9.0pt;font-family:"\000B";color:#3B3B3B'>fat</span><span style='font-size:
  9.0pt;mso-ascii-font-family:"\000B";mso-hansi-font-family:"\000B";
  color:#3B3B3B'>表的项数，对大文件存取增加消耗，文件系统效率不高。分区的大小和簇的取值是有关系的，见表</span><span
  lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'>9&nbsp;&nbsp;(</span><span
  lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:red'><a
  href="http://www.sjhf.net/pdf/fat.pdf" target="_bland"><span
  style='font-size:8.0pt;font-family:宋体;mso-ascii-font-family:"\000B";
  mso-hansi-font-family:"\000B"'>单击此处查看</span><span style='font-size:8.0pt'>PDF</span><span
  style='font-size:8.0pt;font-family:宋体;mso-ascii-font-family:"\000B";
  mso-hansi-font-family:"\000B"'>版全文</span><span style='font-size:8.0pt'>)</span></a></span><span
  lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'><o:p></o:p></span></p>
  <table border=1 cellpadding=0 width=493 style='width:369.5pt;mso-cellspacing:
   1.5pt;border:none' id=table20>
   <tr>
    <td colspan=6 style='border:none;padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><i><span
    style='font-size:10.0pt;font-family:宋体;mso-ascii-font-family:"\000B";
    mso-hansi-font-family:"\000B";color:#006699'>图</span></i><i><span
    lang=EN-US style='font-size:10.0pt;font-family:"\000B";color:#006699'>4.3.11
    Fat16</span></i><i><span style='font-size:10.0pt;font-family:宋体;mso-ascii-font-family:
    "\000B";mso-hansi-font-family:"\000B";color:#006699'>的组织形式</span></i><span
    lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'><o:p></o:p></span></p>
    </td>
   </tr>
   <tr>
    <td width="7%" style='width:7.0%;border:solid teal .75pt;background:silver;
    padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><span
    style='font-size:10.0pt;font-family:宋体;mso-ascii-font-family:"\000B";
    mso-hansi-font-family:"\000B";color:#006699'>引导扇区</span><span lang=EN-US
    style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'><o:p></o:p></span></p>
    </td>
    <td width="19%" style='width:19.0%;border:solid teal .75pt;background:silver;
    padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><span
    lang=EN-US style='font-size:10.0pt;font-family:"\000B";color:#006699'>FAT1</span><span
    lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'><o:p></o:p></span></p>
    </td>
    <td width="18%" style='width:18.0%;border:solid teal .75pt;background:silver;
    padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><span
    lang=EN-US style='font-size:10.0pt;font-family:"\000B";color:#006699'>FAT2(</span><span
    style='font-size:10.0pt;font-family:宋体;mso-ascii-font-family:"\000B";
    mso-hansi-font-family:"\000B";color:#006699'>重复的</span><span lang=EN-US
    style='font-size:10.0pt;font-family:"\000B";color:#006699'>)</span><span
    lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'><o:p></o:p></span></p>
    </td>
    <td width="13%" style='width:13.0%;border:solid teal .75pt;background:silver;
    padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><span
    style='font-size:10.0pt;font-family:宋体;mso-ascii-font-family:"\000B";
    mso-hansi-font-family:"\000B";color:#006699'>根文件夹</span><span lang=EN-US
    style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'><o:p></o:p></span></p>
    </td>
    <td width="30%" style='width:30.0%;border:solid teal .75pt;background:silver;
    padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><span
    style='font-size:10.0pt;font-family:宋体;mso-ascii-font-family:"\000B";
    mso-hansi-font-family:"\000B";color:#006699'>其他文件夹及所有文件</span><span
    lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'><o:p></o:p></span></p>
    </td>
    <td width="13%" style='width:13.0%;border:solid teal .75pt;background:silver;
    padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><span
    style='font-size:10.0pt;font-family:宋体;mso-ascii-font-family:"\000B";
    mso-hansi-font-family:"\000B";color:#006699'>剩余扇区</span><span lang=EN-US
    style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'><o:p></o:p></span></p>
    </td>
   </tr>
   <tr>
    <td width="7%" style='width:7.0%;border:none;padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><i><span
    lang=EN-US style='font-size:10.0pt;font-family:"\000B";color:#006699'>1</span></i><i><span
    style='font-size:10.0pt;font-family:宋体;mso-ascii-font-family:"\000B";
    mso-hansi-font-family:"\000B";color:#006699'>扇区</span></i><span
    lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'><o:p></o:p></span></p>
    </td>
    <td width="19%" style='width:19.0%;border:none;padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><i><span
    style='font-size:10.0pt;font-family:宋体;mso-ascii-font-family:"\000B";
    mso-hansi-font-family:"\000B";color:#006699'>实际情况取大小</span></i><span
    lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'><o:p></o:p></span></p>
    </td>
    <td width="18%" style='width:18.0%;border:none;padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><i><span
    style='font-size:10.0pt;font-family:宋体;mso-ascii-font-family:"\000B";
    mso-hansi-font-family:"\000B";color:#006699'>同</span></i><i><span
    lang=EN-US style='font-size:10.0pt;font-family:"\000B";color:#006699'>FAT1</span></i><span
    lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'><o:p></o:p></span></p>
    </td>
    <td width="13%" style='width:13.0%;border:none;padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><i><span
    lang=EN-US style='font-size:10.0pt;font-family:"\000B";color:#006699'>32</span></i><i><span
    style='font-size:10.0pt;font-family:宋体;mso-ascii-font-family:"\000B";
    mso-hansi-font-family:"\000B";color:#006699'>个扇区</span></i><span
    lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'><o:p></o:p></span></p>
    </td>
    <td width="30%" style='width:30.0%;border:none;padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><i><span
    style='font-size:10.0pt;font-family:宋体;mso-ascii-font-family:"\000B";
    mso-hansi-font-family:"\000B";color:#006699'>开始簇编号</span></i><i><span
    lang=EN-US style='font-size:10.0pt;font-family:"\000B";color:#006699'>(</span></i><i><span
    style='font-size:10.0pt;font-family:宋体;mso-ascii-font-family:"\000B";
    mso-hansi-font-family:"\000B";color:#006699'>从</span></i><i><span
    lang=EN-US style='font-size:10.0pt;font-family:"\000B";color:#006699'>2</span></i><i><span
    style='font-size:10.0pt;font-family:宋体;mso-ascii-font-family:"\000B";
    mso-hansi-font-family:"\000B";color:#006699'>开始</span></i><i><span
    lang=EN-US style='font-size:10.0pt;font-family:"\000B";color:#006699'>)</span></i><span
    lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'><o:p></o:p></span></p>
    </td>
    <td width="13%" style='width:13.0%;border:none;padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><i><span
    style='font-size:10.0pt;font-family:宋体;mso-ascii-font-family:"\000B";
    mso-hansi-font-family:"\000B";color:#006699'>不足一簇</span></i><span
    lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'><o:p></o:p></span></p>
    </td>
   </tr>
  </table>
  <p style='line-height:150%;word-break:break-all'><span lang=EN-US
  style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'>&nbsp;<o:p></o:p></span></p>
  <table border=1 cellpadding=0 width=360 style='width:269.65pt;mso-cellspacing:
   1.5pt' id=table23>
   <tr>
    <td colspan=3 style='padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><span
    style='font-size:9.0pt;font-family:宋体;mso-ascii-font-family:"\000B";
    mso-hansi-font-family:"\000B";color:#3B3B3B'>表</span><span lang=EN-US
    style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'>9&nbsp; FAT16</span><span
    style='font-size:9.0pt;font-family:宋体;mso-ascii-font-family:"\000B";
    mso-hansi-font-family:"\000B";color:#3B3B3B'>分区大小与对因簇大小</span><span
    lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'><o:p></o:p></span></p>
    </td>
   </tr>
   <tr>
    <td width="26%" style='width:26.0%;padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><span
    style='font-size:9.0pt;font-family:宋体;mso-ascii-font-family:"\000B";
    mso-hansi-font-family:"\000B";color:#3B3B3B'>分区空间大小</span><span
    lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'><o:p></o:p></span></p>
    </td>
    <td width="29%" style='width:29.0%;padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><span
    style='font-size:9.0pt;font-family:宋体;mso-ascii-font-family:"\000B";
    mso-hansi-font-family:"\000B";color:#3B3B3B'>每个簇的扇区</span><span
    lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'><o:p></o:p></span></p>
    </td>
    <td width="18%" style='width:18.0%;padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><span
    style='font-size:9.0pt;font-family:宋体;mso-ascii-font-family:"\000B";
    mso-hansi-font-family:"\000B";color:#3B3B3B'>簇空间大小</span><span lang=EN-US
    style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'><o:p></o:p></span></p>
    </td>
   </tr>
   <tr>
    <td width="26%" style='width:26.0%;padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><span
    lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'>0MB-32MB<o:p></o:p></span></p>
    </td>
    <td width="29%" style='width:29.0%;padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><span
    lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'>1<o:p></o:p></span></p>
    </td>
    <td width="18%" style='width:18.0%;padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><span
    lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'>512</span><span
    style='font-size:9.0pt;font-family:宋体;mso-ascii-font-family:"\000B";
    mso-hansi-font-family:"\000B";color:#3B3B3B'>个字节</span><span lang=EN-US
    style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'><o:p></o:p></span></p>
    </td>
   </tr>
   <tr>
    <td width="26%" style='width:26.0%;padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><span
    lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'>33MB-64MB<o:p></o:p></span></p>
    </td>
    <td width="29%" style='width:29.0%;padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><span
    lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'>2<o:p></o:p></span></p>
    </td>
    <td width="18%" style='width:18.0%;padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><span
    lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'>1k<o:p></o:p></span></p>
    </td>
   </tr>
   <tr>
    <td width="26%" style='width:26.0%;padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><span
    lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'>65MB-128MB<o:p></o:p></span></p>
    </td>
    <td width="29%" style='width:29.0%;padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><span
    lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'>4<o:p></o:p></span></p>
    </td>
    <td width="18%" style='width:18.0%;padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><span
    lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'>2k<o:p></o:p></span></p>
    </td>
   </tr>
   <tr>
    <td width="26%" style='width:26.0%;padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><span
    lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'>129MB-225MB<o:p></o:p></span></p>
    </td>
    <td width="29%" style='width:29.0%;padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><span
    lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'>8<o:p></o:p></span></p>
    </td>
    <td width="18%" style='width:18.0%;padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><span
    lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'>4k<o:p></o:p></span></p>
    </td>
   </tr>
   <tr>
    <td width="26%" style='width:26.0%;padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><span
    lang=EN-US style='font-size:9.0pt;font-family:"\000B";color:#3B3B3B'>256MB-511MB<o:p></o:p></span></p>
    </td>
    <td width="29%" style='width:29.0%;padding:.75pt .75pt .75pt .75pt'>
    <p class=MsoNormal align=center style='text-align:center;line-height:150%'><span