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+<?php
+# dvdisaster: English homepage translation
+# Copyright (C) 2004-2012 Carsten Gnörlich
+#
+# UTF-8 trigger: äöüß 
+#
+# Include our PHP sub routines, then call begin_page()
+# to start the HTML page, insert the header, 
+# navigation and news if appropriate.
+
+require("../include/dvdisaster.php");
+require("../include/screenshot.php");
+begin_page();
+?>
+
+<!-- Insert actual page content below -->
+
+<h3 class="top">The linear reading strategy</h3>
+
+dvdisaster contains two different reading strategies.<p>
+
+<b>The linear reading strategy is recommended for:</b><p>
+<ul>
+<li><a href="howtos23.php">creating images</a> from undamaged media, e.g. to generate the error correction file</li>
+<li><a href="howtos12.php">scanning the medium</a> for reading speed and read errors</li>
+</ul>
+
+<b>The <a href="qa35.php">adaptive reading strategy</a> is recommended for:</b><p>
+<ul>
+<li> <a href="howtos42.php">extracting data</a> from damaged media
+</li>
+</ul>
+
+<pre> </pre>
+
+<b>Properties of the linear reading strategy.</b><p>
+
+<?php begin_screen_shot("Weak CD","weak-cd.png"); ?>
+Optical media are organized into sectors which are 
+continously numbered beginning with zero. Each sector contains 2048 bytes of data.<p>
+
+The linear reading strategy reads the medium from the start (sector 0)
+until the end (last sector). The reading speed is shown graphically to provide
+information about the <a href="#quality">medium quality</a>:
+<?php end_screen_shot(); ?><p>
+
+<pre> </pre>
+
+
+<a name="configure"></a>
+<b>Configuration.</b><p>
+
+<b>Number of sectors to skip after a read error.</b>
+Reading attempts for defective sectors are slow and may wear out the drive mechanics
+under unfavourable conditions. A series of read errors, spread over a continous sector
+range, is more common than single spot defects. Therefore a 
+<a href="howtos11.php#read_attempts"> configuration option</a> exists so that a certain number
+of sectors will be skipped after the occurance of a read error. The skipped sectors are
+assumed to be defective without further reading attempts. 
+Some guide lines for selecting the number of skipped sectors are:<p>
+
+<ul>
+<li>Skipping a large number of sectors (e.g. <b>1024</b>) gives a quick overview of the 
+degree of damage, but will usually not collect enough data for repairing the medium image.
+<p></li> 
+<li>Smaller values like <b>16, 32 or 64</b> are a good trade-off:
+The processing time will be considerably shortened, but still enough data for repairing
+the image will be collected.<p></li>
+</ul>
+
+On DVD media read errors do usually extend over at least 16 sectors for technical
+reasons. Therefore a sector skip less than 16 is not recommended for DVD media.
+<p>
+
+<a name="range"></a>
+<b>Limiting the reading range.</b>
+Reading can be
+<a href="howtos11.php#image">limited to a given range of sectors</a> in the
+"Image" preferences tab. This comes in handy
+during multiple read attempts of damaged media.
+
+<pre> </pre>
+
+<a name="quality"></a>
+<b>Estimating media quality.</b><p>
+
+<a name="error"></a>
+<b>The speed curve.</b>
+Most drives will slow down while reading medium areas which are in bad condition:
+<ul>
+<li>
+Drops in the reading speed can be a warning for an imminent medium failure.
+</li>
+<li>
+However some drives will read with full speed until the bitter end.
+With such drives media deterioration may not show up in the reading curve
+until actual read errors occur.
+</li>
+</ul><p>
+
+The reading curve is most accurate when using the
+<a href="howtos10.php"> "Scan"</a> function. During the
+<a href="howtos23.php">"Read"</a> operation the read data will be written to
+the hard drive at the same time, which may cause irregularities in the reading
+curve depending on the operating system and hardware used.<p>
+
+<b>Read errors.</b>
+Read errors cause <a href="howtos13.php#defective">red markings in the spiral</a> or respective
+messages at the command line. 
+This means that the medium could not be
+read at these places during the current reading pass:
+<ul>
+<li>The medium is most likely defective.</li>
+<li>The image should be 
+<a href="howtos40.php">repaired</a> as soon as possible and then be transferred
+to a new medium.</li>
+</ul>
+
+<!-- do not change below -->
+
+<?php
+# end_page() adds the footer line and closes the HTML properly.
+
+end_page();
+?>