In-file delta
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In-file delta technology is a method of examining the content of a computer file and comparing it with a copy of that file in order to ascertain the sections of the file that have changed. This is used in various applications that require changes to large files to be transported across relatively slow media (such as ADSL). It is used in some more advanced Remote backup systems in order that incremental backup copies of large files can be taken very quickly.
The process is based around a series of checksum values taken of various blocks of a file which are then compared to a modified file. Any checksums that do not match indicate a change, and this section of the file will be copied. At some point the original file and all of the changed sections of the file will need to be merged to create an up to date copy of that file.
