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@@ -1,16 +1,29 @@ Description Lziprecover is a data recovery tool and decompressor for files in the -lzip compressed data format (.lz) able to repair slightly damaged files, -recover badly damaged files from two or more copies, extract data from -damaged files, decompress files and test integrity of files. +lzip compressed data format (.lz), able to repair slightly damaged +files, recover badly damaged files from two or more copies, extract data +from damaged files, decompress files and test integrity of files. + +The lzip file format is designed for long-term data archiving. It is +clean, provides very safe 4 factor integrity checking, and is backed by +the recovery capabilities of lziprecover. Lziprecover is able to recover or decompress files produced by any of the compressors in the lzip family; lzip, plzip, minilzip/lzlib, clzip -and pdlzip. It makes lzip files resistant to bit-flip, one of the most -common forms of data corruption, and its recovery capabilities -contribute to make of the lzip format one of the best options for -long-term data archiving. +and pdlzip. + +Lziprecover makes lzip files resistant to bit-flip (one of the most +common forms of data corruption), and can safely merge multiple damaged +backup copies. + +If the cause of file corruption is damaged media, the combination +GNU ddrescue + lziprecover is the best option for recovering data from +multiple damaged copies. + +If a file is too damaged for lziprecover to repair it, all the +recoverable data in all members of the file can be extracted with the +'-D' option. Lziprecover is able to efficiently extract a range of bytes from a multi-member file, because it only decompresses the members containing @@ -27,24 +40,20 @@ damaged files themselves are never modified. When decompressing or testing file integrity, lziprecover behaves like lzip or lunzip. -If the files are too damaged for lziprecover to repair them, data from -damaged members can be partially recovered writing it to stdout. - -To give you an idea of its possibilities, when merging two copies each +To give you an idea of its possibilities, when merging two copies, each of them with one damaged area affecting 1 percent of the copy, the probability of obtaining a correct file is about 98 percent. With three -such copies the probability rises to 99.97 percent. For large files with -small errors, the probability approaches 100 percent even with only two -copies. +such copies the probability rises to 99.97 percent. For large files (a +few MB) with small errors (one sector damaged per copy), the probability +approaches 100 percent even with only two copies. -If the cause of file corruption is damaged media, the combination -GNU ddrescue + lziprecover is the best option for recovering data from -multiple damaged copies. +Lziprecover is not a replacement for regular backups, but a last line of +defense for the case where the backups are also damaged. -This package also includes unzcrash, a program written to test -robustness to decompression of corrupted data, inspired by unzcrash.c -from Julian Seward's bzip2. Type 'make unzcrash' in the lziprecover -directory to build it. Then try 'unzcrash --help'. +The lziprecover package also includes unzcrash, a program written to +test robustness to decompression of corrupted data, inspired by +unzcrash.c from Julian Seward's bzip2. Type 'make unzcrash' in the +lziprecover source directory to build it. Then try 'unzcrash --help'. Copyright (C) 2009, 2010, 2011, 2012, 2013 Antonio Diaz Diaz. |