Dar

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This is not a complete article: This is a draft, a work in progress that is intended to be published into an article, which may or may not be ready for inclusion in the main wiki. It should not necessarily be considered factual or authoritative.

Parent page: Storage and file management

The dar (stands for Disk ARchiver) utility was written from the ground up as a modern replacement to the classical Unix tar tool. First released in 2002, dar is open source, is actively maintained, and can be compiled on any Unix-like system.

Similar to tar, dar supports full / differential / incremental backups. Unlike tar, each dar arhive includes a file index for fast file access and restore -- this is especially useful for large archives! dar has built-in compression on a file-by-file basis, making it more resilient against data corruption, and you can optionally tell it not to compress already highly compressed files such as mp4 and gz. dar supports strong encryption, can split archives at 1-byte resolution, supports extended file attributes, sparse files, hard and symbolic (soft) links, can detect data corruption in both headers and saved data and recover with minimal data loss, and has many other desirable features. On the dar page you can find a detailed feature-by-feature tar-to-dar comparison.

Where to find dar

Since dar can be compiled on the command-line, you can install it easily on Linux and MacOS. On Compute Canada clusters a slightly out-of-date version can be found in /cvmfs:

[user_name@localhost]$ which dar
/cvmfs/soft.computecanada.ca/nix/var/nix/profiles/16.09/bin/dar
[user_name@localhost]$ dar --version
dar version 2.5.3, Copyright (C) 2002-2052 Denis Corbin
...

If you want a newer version, you can compile it from source:

[user_name@localhost]$ wget https://sourceforge.net/projects/dar/files/dar/2.6.3/dar-2.6.3.tar.gz
[user_name@localhost]$ tar xvfz dar-*.gz && /bin/rm -f dar-*.gz
[user_name@localhost]$ cd dar-*
[user_name@localhost]$ ./configure --prefix=$HOME/dar --disable-shared
[user_name@localhost]$ make
[user_name@localhost]$ make install-strip
[user_name@localhost]$ $HOME/dar/bin/dar --version