Your tarball is uncompressed. The extension
.bz is obsolete and misleading.
You can decompress using the following command:
tar xvf data_or.tar.bz
What probably happened here is that
data_or.tar.bz was created with the
--auto-compress switch (or
tar -cavf) that chooses the compression algorithm from the supplied extension.
The proper extension for
bzip2 compressed files is
.bz2, while the
.bz extension is for
bzip compressed files.
bzip uses arithmetic encoding (which is a patented algorithm), so
bzip2 was created in 1997 as a patent-free alternative. As a result,
bzip are incompatible.
tar cannot handle
bzip (de)compression, so the
--auto-compress switch resulted in an uncompressed tarball.