ZFS compression is off by default, but recommended to be used, as the performance gain for typical data is significant.

• LZ4: is a stream algorithm offering extremely rapid compression and decompression, and is a performance win for the majority of use cases.
• GZIP: is the venerable algorithm all Unix-like users know and love.
  • It can be implemented with compression levels 1-9, with increasing compression ratio and CPU usage as levels approach 9.
  • gzip may be a win for all-text (or otherwise extremely compressible) use-cases, but frequently results in CPU bottlenecks otherwise—use with caution, particularly at higher levels.
• LZJB: is the original algorithm used by ZFS.
  • It is deprecated, and should no longer be used.
  • LZ4 is superior in every metric.
• ZLE: is Zero Level Encoding.
  • It leaves normal data alone entirely, but will compress large sequences of zeroes.
  • Useful for entirely in-compressible datasets (e.g. JPEG, MP4, or other already-compressed formats), since it ignores the in-compressible data, but compresses slack space on final records.