Local compression compresses segments before writing them to disk. It uses common, industry standard algorithms (for example, Iz, gz, and gzfast). The default compression algorithm used by Data Domain systems is Iz.
Local compression is similar to zipping a file to reduce the file size. Zip is a file format used for data compression and archiving. A zip file contains one or more files that have been compressed, to reduce file size, or stored as is. The zip file format permits a number of compression algorithms.
Local compression can be turned off.
It is good practice to run a cleaning operation after the first full backup to a Data Domain system. The initial local compression on a full backup is generally a factor of 1.5 to 2.5. An immediate cleaning operation gives additional compression by another factor of 1.15 to 1.2 and reclaims a corresponding amount of disk space.