![]() ![]() Each group of original data sectors and the added ECC sector(s) forms a "cluster". It is important to point out that each unit of ECC data dvdisaster places at the end is calculated from sectors of the original data spread around in the original image. In contrast, reading at the image level uses direct communication with the drive hardware to access the data sectors. Therefore, files or parts from files may be lost even though the respective data sectors would still be readable by the hardware. Or the mapping of data sectors to files is incomplete. The list of files on the medium may be truncated. But a limitation of the file-based approach arises when data sectors are damaged which have book-keeping functions in the file system. It does not apply a file-based data recovery, as reading a defective medium at the file level means trying to read as much data as possible from each file. dvdisaster can then repeatedly rescan just the missing parts until all damaged areas have been filled in by correct data.ĭifference with other Reed-Solomon implementations ĭvdisaster applies an image-based approach to data recovery. The entire disc can be read into an image, skipping damaged parts. In this way a damaged disc may be fully recoverable by installing the software, accessing the Reed-Solomon error correcting code using dvdisaster and rebuilding the image (to hard disk).ĭvdisaster can be helpful to recover the contents of a damaged disc even when no ECC data is available. When a CD or DVD has been augmented in RS02 mode, the 'augmented' section of the data remains invisible to the normal user, and the disc remains fully compatible with computers without knowledge of or installation of dvdisaster. Alternatively, in RS02 mode, the ECC data is appended to the end of the disc image before the image is burned to disc. In RS01 mode, the generated data is created from a disc image and is stored in a separate file, which must be written on some other medium. The two modes of ECC data generation in dvdisaster make use of Reed–Solomon codes. ![]() By utilizing the ECC data previously generated by dvdisaster, damaged parts of the disc data can be recovered. When an optical disc is physically damaged (such as by scratching), or has begun to deteriorate, some parts of the data on the disc may become unreadable. dvdisaster is free software available under the GNU General Public License. This program can be used either to generate Error-Correcting Code (ECC) data from an existing media or to augment an ISO image with ECC data prior to being written onto a medium. dvdisaster works exclusively at the image level. 27 September 2021 20 months ago ( 27 September 2021)įreeBSD, Linux, NetBSD ( Cross-platform till version 0.72.3)ĭvdisaster is a computer program aimed to enhance data survivability on optical discs by creating error detection and correction data, which is used for data recovery. ![]()
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