Ext4 with journaling. I've played around with XFS as well just to see what would happen. No major difference. I'm certain it's caused by the way Postgres builds its indices.
While I really like ZFS personally for 99% of things, for "need maximum performance with PostgreSQL and we're already pushing high end hardware to the maximum" ZFS is reportedly the wrong choice.
While I really like ZFS personally for 99% of things, for "need maximum performance with PostgreSQL and we're already pushing high end hardware to the maximum" ZFS is reportedly the wrong choice.