Sun marketed the combination of PostgreSQL and ZFS quite heavily. But IIRC most of the success stories they presented involved what was decidedly non-OLTP read

Sun marketed the combination of PostgreSQL and ZFS quite heavily. But IIRC most of the success stories they presented involved what was decidedly non-OLTP read heavy workload with somewhat ridiculously large databases. One of the case studies even involved using PostgreSQL on ZFS as an archival layer for Oracle, with the observation that what is a large Oracle database is medium-sized one for PostgreSQL (and probably even more so if it is read mostly and on ZFS). Sunhad some recommendations for tuning PostgreSQL performance on ZFS, but the recommendations seemed weird or even wrong for OLTP on top of CoW filesystem (I assume that these recommendations were meant for the above mentioned DWH/archival scenarios).