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Monday, 18 May 2015 00:00

par2 utility: Adding recovery records to archives

  File Systems
 
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The par2 utility allows adding a recovery record to files by Reed-Solomon algorithm.

This allows recovering the original file in the case of light (or even serious) damages.

This is performed as follows:

   $ sudo aptitude install par2 #(cd /usr/ports/archivers/parchive; make instal)
   $ ls
     dump.sql.gz
   $ par2 create -v -r10 -n1 -m500 dump.sql.gz
   $ ls
     dump.sql.gz dump.sql.gz.par2 dump.sql.gz.vol000+100.par2

This command adds 10% (-r10) of redundant information to the data, writes it all in a single file (-n1), and in so doing the par2 utility is allowed to use 500Mb of RAM (-m500).

The *.par2 files should be written on the disk together with a dump.

We can repair the damaged file using the following command:

   $ par2 repair dump.sql.gz.par2

Learn more about Reed-Solomon codes:

http://www.insidepro.com/kk/027/027r.shtml

Last modified on Monday, 18 May 2015 19:12
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