windows-nt/Source/XPSP1/NT/inetsrv/query/web/html/help/scanhlp.htm
2020-09-26 16:20:57 +08:00

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<title>Microsoft Index Server Guide: Scanning</title>
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<!--Headerbegin--><p align=center><a name="TOP"><img src="onepix.gif" alt="Space" align=middle width=1 height=1></a> <a href="default.htm#Top"><img src="toc.gif" alt=" Contents" align=middle border=0 width=89 height=31></a> <a href="filtrhlp.htm"><img src="previous.gif" alt="Previous" align=middle border=0 width=32 height=31></a> <a href="webhits.htm"><img src="next.gif" alt="Next" align=middle border=0 width=32 height=31></a> </p>
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<!--Headerend--><p><a name="Scanning"><font size=6><strong>Scanning</strong></font></a></p>
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<p><a href="scanhlp.htm#FullScan">Full Scan</a> <br>
<a href="scanhlp.htm#IncrementalScan">Incremental Scan</a> <br>
<a href="scanhlp.htm#ForceScan">Forcing a Scan from Administration Pages</a> <br>
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<!--ChaptocEnd--><p>The process of inventorying the virtual roots (and the physical directories pointed to by the virtual roots) to determine which
documents should be indexed is called <em>scanning</em>. By default, all readable virtual roots are indexed. If some readable virtual
roots should not be indexed, they can be <a href="adminhlp.htm#AddVRoot">configured</a> by the administrator.</p>
<p>There are two basic types of scans:</p>
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<li><a href="#FullScan">Full Scan</a></li>
<li><a href="#IncrementalScan">Incremental Scan</a></li>
</ul>
<p>There is no manual intervention needed for either of the scans, because Microsoft Index Server automatically detects what
type of scan to do and does it without user intervention.</p>
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<h1><a href="#TOP"><img src="up.gif" alt="To Top" align=middle border=0 width=14 height=11></a><a name="FullScan">Full Scan</a></h1>
<p>In a full scan, all the documents in the directories that are inventoried are added to the list of documents to be filtered. A full
scan is performed the first time a directory is added to the list of indexed directories. A full scan is also performed as part of
recovery if a serious error occurs.</p>
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<h1><a href="#TOP"><img src="up.gif" alt="To Top" align=middle border=0 width=14 height=11></a><a name="IncrementalScan">Incremental Scan</a></h1>
<p>In an incremental scan, only the documents that were modifed since the last time they were filtered are added to the list of
documents to be filtered. On startup of Index Server, an incremental scan is performed on all the <em>indexed directories</em>. This
allows Index Server to determine which files were modifed when it was not running.</p>
<p>During normal operation of Index Server, all changes to the documents in the indexed directories are automatically tracked if
the indexed directories are on computers running Windows NT. <em>Indexed directories</em> are the set of all directories in the
indexed virtual roots. Some file servers, such as Novell NetWare and Microsoft&#174; Windows&#174; 95 file server, do not support
automatic change notification. When a virtual root points to a remote share that does not support automatic change notification,
Index Server does periodic scans of that share. The frequency of these periodic scans is controlled by the registry setting
<a href="reghelp.htm#ForcedNetPathScanInterval">ForcedNetPathScanInterval</a><em>.</em></p>
<p>Sometimes an incremental scan is also performed if the system <em>loses</em> change notifications. This can happen if the update rate of
documents is very high and the buffer used to get change notifications from Windows NT overflows.</p>
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<h1><a href="#TOP"><img src="up.gif" alt="To Top" align=middle border=0 width=14 height=11></a><a name="ForceScan">Forcing a Scan from Administration Pages</a></h1>
<p>An administrator can force either a full scan or an incremental scan on any of the indexed virtual roots by choosing the <em>Force
scan virtual roots </em>option from the <a href="/srchadm/admin.htm">administration page</a>. This will show the list of virtual roots. By default, no scan will be
selected for any of the virtual roots. You can select the appropriate type of scan for the virtual root and click <em>Submit</em>. </p>
<p>You can force a full scan when a new <a href="filtrhlp.htm#FilterDLLs">filter DLL</a> is installed or if you do not want to wait for the periodic scan on a remote
virtual root. <font color="#400040">Queries will continue to return documents, but query speed may slow down during the scanning and filtering.</font></p>
<p><font color="#400040"><strong>Note&#160;&#160;&#160;</strong></font>Forcing a full scan results in all the files in a scope to be refiltered and could take a long time. </p>
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