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<span class="fxxl"><b>dvdisaster</b></span>
<i>Version 0.72.6 / 0.79 (devel-3)</i>
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<span class="fxxl"> </span><a href="http://dvdisaster.net/en/">To the Internet version</a>
<a href="../cs/howtos63.html"></a>
<a href="../de/howtos63.html"></a>
<a href="../ru/howtos63.html"></a>
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<span class="fs"><b>Contents</b></span>
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<tr><td colspan=3><span class="fs"><a href="news.html">News</a></span></td></tr>
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<tr><td colspan=3><span class="fs"><a href="index.html">Overview</a></span></td></tr>
<tr><td></td><td></td><td style="height:10px;"></td></tr>
<tr><td colspan=3><span class="fs"><a href="howtos.html">Howtos</a></span></td></tr>
<tr><td style="width:1%; vertical-align:top;">·</td><td colspan=2><span class="fs"><a href="howtos60.html">The big picture</a></span></td></tr>
<tr><td></td><td style="vertical-align:top; font-size:small;">-</td><td><span class="fs"><a href="howtos61.html">error correction</a></span></td></tr>
<tr><td></td><td style="vertical-align:top; font-size:small;">-</td><td><span class="fs"><a href="howtos62.html">correct usage</a></span></td></tr>
<tr><td></td><td style="vertical-align:top; font-size:small;">-</td><td><span class="fs">incorrect usage</span></td></tr>
<tr><td style="width:1%; vertical-align:top;">·</td><td colspan=2><span class="fs"><a href="howtos10.html">Scanning media for errors</a></span></td></tr>
<tr><td style="width:1%; vertical-align:top;">·</td><td colspan=2><span class="fs"><a href="howtos20.html">Putting error correction data on a separate file</a></span></td></tr>
<tr><td style="width:1%; vertical-align:top;">·</td><td colspan=2><span class="fs"><a href="howtos30.html">Putting error correction data on the medium</a></span></td></tr>
<tr><td style="width:1%; vertical-align:top;">·</td><td colspan=2><span class="fs"><a href="howtos40.html">Recovering media images</a></span></td></tr>
<tr><td style="width:1%; vertical-align:top;">·</td><td colspan=2><span class="fs"><a href="howtos50.html">Getting information about images and error correction data</a></span></td></tr>
<tr><td style="width:1%; vertical-align:top;">·</td><td colspan=2><span class="fs"><a href="howtos90.html">Testing image compatibility</a></span></td></tr>
<tr><td style="width:1%; vertical-align:top;">·</td><td colspan=2><span class="fs"><a href="howtosa0.html">Dialogs and buttons</a></span></td></tr>
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<h3 class="top">Using dvdisaster the wrong way</h3>
Joe bets on his media keeping their content
without additional protection.<p>
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<td class="w15p">10. Feb. 2004</td>
<td class="w65x"><img src="../images/good-cd.png" alt="Icon: Good medium (without read errors)"></td>
<td class="w65x"><img src="../images/good-cd.png" alt="Icon: Good medium (without read errors)"></td>
<td>Joe creates two CDs containing important data. But he does not
make any provisions against data loss on those media.</td>
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<tr><td colspan="4"> <hr> </td></tr>
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<td>14. May 2005</td>
<td><img class="valignt" src="../images/good-cd.png" alt="Icon: Good medium (without read errors)"></td>
<td><img class="valignt" src="../images/good-cd.png" alt="Icon: Good medium (without read errors)"></td>
<td>Joe uses his CDs regularly. After one year they are still perfectly
readable.</td>
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<tr><td colspan="4"> <hr> </td></tr>
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<td>19. Aug 2007</td>
<td><img class="valignt" src="../images/bad-cd.png" alt="Icon: Damaged medium (partially unreadable)"></td>
<td><img class="valignt" src="../images/good-cd.png" alt="Icon: Good medium (without read errors)"></td>
<td>After two more years Joe notices that some data on one CD is no
longer readable.</td>
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<td align="right"><a href="howtos10.html">scanning</a></td>
<td align="center"><img class="valignt" src="../images/down-arrow.png" alt="Icon: Arrow down"></td>
<td align="center"><img class="valignt" src="../images/down-arrow.png" alt="Icon: Arrow down"></td>
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<td>20. Aug 2007</td>
<td><img class="valignt" src="../images/bad-cd.png" alt="Icon: Damaged medium (partially unreadable)"></td>
<td><img class="valignt" src="../images/bad-cd.png" alt="Icon: Damaged medium (partially unreadable)"></td>
<td>Joe downloads dvdisaster and performs
<a href="howtos10.html">a read error scan</a>.
He finds out that the CD contains 25000 unreadable sectors. A scan
of the second CD reveals that it has developed 1500 unreadable sectors
gone unnoticed so far. </td>
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<td align="right">reading</td>
<td align="center"><img class="valignt" src="../images/down-arrow.png" alt="Icon: Arrow down"></td>
<td align="center"><img class="valignt" src="../images/down-arrow.png" alt="Icon: Arrow down"></td>
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<tr><td colspan="4"> <p> </td></tr>
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<td>21. Aug 2007</td>
<td><img class="valignt" src="../images/bad-image.png" alt="Icon: Partial image"></td>
<td><img class="valignt" src="../images/bad-image.png" alt="Icon: Partial image"></td>
<td>Joe uses dvdisaster to
read as much sectors as possible from the
defective media. But since he does not have error correction data
there is no way of recalculating the unreadable sectors.</td>
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<td align="right">many reading<br>attempts</td>
<td align="center"><img class="valignt" src="../images/down-arrow.png" alt="Icon: Arrow down"></td>
<td align="center"><img class="valignt" src="../images/down-arrow.png" alt="Icon: Arrow down"></td>
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<tr><td colspan="4"> <p> </td></tr>
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<td>05. Sep 2007</td>
<td><img class="valignt" src="../images/bad-image.png" alt="Icon: Partial image"></td>
<td><img class="valignt" src="../images/good-image.png" alt="Icon: Complete image"></td>
<td>Joe takes advantage of dvdisaster's feature to complete images
through multiple reading passes. He moves the defective images to
several computers to perform reading attempts with different drives.
After two weeks of trying at least all missing sectors from the second
CD have been read. However on the first CD still 21000 sectors
remain unreadable by any drive he tried.</td>
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<td align="right">only one CD<br>recovered</td>
<td align="center"><img class="valignt" src="../images/down-arrow.png" alt="Icon: Arrow down"></td>
<td align="center"><img class="valignt" src="../images/down-arrow.png" alt="Icon: Arrow down"></td>
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<tr><td colspan="4"> <p> </td></tr>
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<td>06. Sep 2007</td>
<td><img class="valignt" src="../images/bad-cd.png" alt="Icon: Damaged medium (partially unreadable)"></td>
<td><img class="valignt" src="../images/good-cd.png" alt="Icon: Good medium (without read errors)"></td>
<td>Joe dismisses the first CD as unrecoverable and considers himself lucky
to have a complete image from the second CD again.
However if he had created error correction data in time, he'd probably <sup>1)</sup>
saved two weeks of reading attempts and recovered the contents from both CDs.</td></tr>
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<hr>
<sup>1)</sup>The error correction assumes a typical aging process.
If the CD gets severely damaged it becomes unrecoverable even with
error correction data. Do not rely on dvdisaster alone for protecting
important data; instead employ additional measures like creating
additional copies on different types of media.
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<span class="fs">
<i> Copyright 2004-2014 Carsten Gnörlich.<br>
Verbatim copying and distribution of this entire article is permitted in any medium, provided this notice is preserved.
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distrib
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Mageia
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5
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i586
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media
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core-release
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by-pkgid
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d78eb3292f06751eceb873773485a42c
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files
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851
