Logfiles. ZFS with lz4 has given me compression ratios of over 100× with /var/log, due to the huge amount of repetition.
My first test of PostgreSQL on ZFS was also quite instructive. lz4 again achieved respectable compression (>10× for my datasets) and improved throughput several fold (with no other tuning!).
My first test of PostgreSQL on ZFS was also quite instructive. lz4 again achieved respectable compression (>10× for my datasets) and improved throughput several fold (with no other tuning!).