Digital archiving tools

Specifically I prefer bzip2 (even though a lot of my imaging activities from the 1990's, before I knew about bzip2, are squirreled away in zip files and I have not necessarily moved them to bzip2). If for some reason the only copy of a bz2 file became partially corrupted I could know which parts were good and which parts were bad: RECOVERING DATA FROM DAMAGED FILES bzip2 compresses files in blocks, usually 900kbytes long. Each block is handled independently. If a media or transmission error causes a multi-block .bz2 file to become damaged, it may be possible to recover data from the undamaged blocks in the file. The compressed representation of each block is delimited by a 48-bit pattern, which makes it possible to find the block boundaries with reasonable certainty. Each block also carries its own 32-bit CRC, so damaged blocks can be distinguished from undamaged ones. bzip2recover is a simple program whose purpose is to search for blocks in .bz2 files, and write each block out into its own .bz2 file. You can then use bzip2 -t to test the integrity of the resulting files, and decompress those which are undamaged.