Oracle 11g RMAN: BZIP2 vs. ZLIB
Prior to 11g Oracle RMAN had a single compression algorithm, called BZIP2. The algorithm has a very satisfactory compression ratio in terms of decreasing the size of RMAN output. However, high CPU cost makes algorithm not suitable for many sites especially for sites having CPU bottleneck (Data warehouse DBAs?!?:)). As a result people still use hardware compression capabilities of tape drivers (ratios like 1:3) to decrease the backup time and increase the effective write speed of backup drivers. By 11g Oracle introduces a new compression algorithm that is announced to be less compressive but less aggressive in terms of CPU. In this paper you will find comparison of two algorithms with no compressed case.