dvdisaster Version 0.70 | To the Internet version

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Overview
Examples and screen shots
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Questions and Answers
· | Technical Questions
· | Error messages
Background information

### Error messages

3.1 "Warning: 2 sectors missing at the end of the disc".

3.2 Program blocks right after invocation.

3.3 What does "CRC error, sector: n" mean?

3.4 Read errors or wrong image size with -RW/+RW/-RAM media

3.5 My self-written media is recognized as "DVD-ROM" and rejected.

3.6 No drives appear under FreeBSD.

3.7 "Ecc file has been created with version 0.40.7."

3.1 "Warning: 2 sectors missing at the end of the disc"

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 not mean data loss in this case.

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.

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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3.2 Program blocks right after invocation

Under old Linux 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".

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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3.3 What does "CRC error, sector: n" mean?

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:

- 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).
- The computer has some hardware problems, especially when communicating with its mass storage devices.

If you suspect technical problems, try creating another version of the image and error correction files and verify them again. 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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3.4 Read errors or wrong image size with -RW/+RW/-RAM media

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

Problem: | The drive reports the size of the largest image ever written to the medium, not that of the actual image.
Symptoms: | 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.

Problem: | The drive reports the maximum possible medium capacity (typically 2295104 sectors) instead of the number of actually used sectors.
Symptoms: | When reading beyond a certain point of the medium, only read errors occur, but all files on the medium are still readable and complete.

Possible remedy:

| Activate the option for determining the image size from the ISO/UDF or ECC/RS02 file systems.

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

- Execute the "Verify" 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.
- Simply read in the image with the incorrect (larger) size. When invoking the "Fix" function, answer "OK" when you are asked whether the image should be truncated.

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3.5 My self-written media is recognized as "DVD-ROM" and rejected.

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.

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

Try another drive for reading images in these cases.

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3.6 No drives appear under FreeBSD.

- FreeBSD may require a kernel recompile in order for ATAPI drives (nearly all current models) to become usable for dvdisaster.
- You need read and write permission for the respective device (e.g. /dev/pass0).

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3.7 "Ecc file has been created with version 0.40.7."

The CVS versions 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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Copyright 2004-2007 Carsten Gnörlich. Verbatim copying and distribution of this entire article is permitted in any medium, provided this notice is preserved.