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<h3>Error messages</h3>

<a href="#tao">3.1 "Warning: 2 sectors missing at the end of the disc".</a><p>
<a href="#block">3.2 Program blocks right after invocation.</a><p>
<a href="#crc">3.3 What does "CRC error, sector: n" mean?</a><p>
<a href="#rw">3.4 Read errors or wrong image size with -RW/+RW/-RAM media</a><p>
<a href="#dvdrom">3.5 My self-written media is recognized as "DVD-ROM" and rejected.</a><p>
<a href="#freebsd">3.6 No drives appear under FreeBSD.</a><p>
<a href="#v40error">3.7 "Ecc file has been created with version 0.40.7."</a><p>

<hr><p>

<b><a name="tao">3.1 "Warning: 2 sectors missing at the end of the disc"</a></b><p>
This warning appears with CD media written in "TAO" (track at once) mode.
Some drives report an image size which is 2 sectors too large for such media,
producing 2 pseudo read errors at the end of the medium 
which do <i>not</i> mean data loss in this case.<p>

Since the writing mode can not be determined from the medium, dvdisaster assumes
a "TAO" CD if exactly the last two sectors are unreadable, and trims the image
accordingly. It is up to you to decide whether this is okay. You can
advise dvdisaster to treat these sectors as real read errors by using the
--dao option or 
the preferences tab for reading/scanning.<p>

To avoid these problems, consider using the "DAO / Disc at once" (sometimes
also called "SAO / Session at once") mode for writing single session media. 
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<b><a name="block">3.2  Program blocks right after invocation</a></b><p>
Using old Linux kernel versions (kernel 2.4.x) the program occasionally 
blocks right after the start and before any actions are
carried out. It can not be terminated using Ctrl-C or "kill -9".<p>

Eject the medium to make the program terminate. Insert the medium again
and wait until the drive recognizes the medium and spins down.
Calling dvdisaster again should work now.
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<b><a name="crc">3.3 What does "CRC error, sector: n" mean?</a></b><p>
The respective sector could be read, but the checksum of its contents does
not match the value noted in the error correction file.  Some possible causes are:<p>

<ul>
<li>The image has been mounted with write permission and
was therefore altered (typical evidence: CRC errors in sector 64 and in
sectors 200 to 400).</li>
<li>The computer has some hardware problems, especially when
communicating with its mass storage devices.</li>
</ul>


If you suspect technical problems, try creating another version of the image 
and error correction files and <a href="howtos50.php">verify
them again</a>.
When the error disappears or surfaces at a different location,
your computer may be suffering from defective memory, 
broken drive cabling, or wrong CPU/system frequency settings.
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<b><a name="rw">3.4 Read errors or wrong image size with -RW/+RW/-RAM media</a></b><p>

Some drives report incorrect image sizes when -RW/+RW/-RAM media are used. Two common
cases are:<p>

<table>
<tr><td valign="top">Problem:</td>
<td>The drive reports the size of the largest image ever written to the medium, not that
of the actual image.
</td></tr>
<tr><td valign="top">Symptoms:</td>
<td>After erasing a medium it is written with a file sized about 100MB.
But the image read back is several GB long and contains the remainings
of older images.
</td></tr>
<tr><td><pre> </pre></td><td></td></tr>
<tr><td valign="top">Problem:</td>
<td>The drive reports the maximum possible medium capacity (typically 2295104 sectors)
instead of the number of actually used sectors.
</td></tr>
<tr><td valign="top">Symptoms:</td>
<td>When reading beyond a certain point of the medium, only read errors occur,
but all files on the medium are still readable and complete.
</td></tr>
</table><p>

Possible remedy:<p>

<table width=100%><tr><td bgcolor=#000000 width=2><img width=1 height=1 alt=""></td><td>
Activate the option for determining the
image size from the ISO/UDF file system or from the ECC/RS02 data.
</td></tr></table><p>

If the required ISO/UDF sectors are unreadable and you are using error correction files
to recover damaged media there are two possible workarounds:

<ul>
<li>Execute the <a href="howtos50.php">"Verify"</a> function with only
the error correction file being selected/given. Note down the correct image size 
from the output and restrict the
reading range accordingly.
</li>
<li>Simply read in the image with the incorrect (larger) size.
When invoking the <a href="howtos40.php#repair">"Fix"</a> function,
answer "OK" when you are asked whether the image should be truncated.
</li>
</ul>

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<b><a name="dvdrom">3.5 My self-written media is recognized as "DVD-ROM" and rejected.</a></b><p>

The medium book type has probably been set to "DVD-ROM". Typically, a drive
capable of writing the same media format is required for processing the medium
with dvdisaster.<p>

For example, a two-layered DVD+R with a wrong book type 
may only be accepted on a burner which can write such media.<p>

Try another drive for reading images in these cases.

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<b><a name="freebsd">3.6 No drives appear under FreeBSD.</a></b><p>

<ul>
<li>FreeBSD may require a <a href="download10.php#freebsd">kernel recompile</a>
in order for ATAPI drives (nearly all current models) to become usable for
dvdisaster.
<li>You need read and write permission for the respective device
(e.g. /dev/pass0).
</ul>

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<b><a name="v40error">3.7 "Ecc file has been created with version 0.40.7."</a></b><p>

The <a href="http://sourceforge.net/cvs/?group_id=157550">CVS versions</a>
of dvdisaster mark their ecc files with a special bit. This causes dvdisaster
versions upto 0.65 to falsely display the above error message. Please use the
CVS versions only together with dvdisaster 0.66 or newer versions.

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