> Am I right to assume that "writeback" is both fastest and at > the same time as safe to use as ordered? Maybe any of you > did some benchmarks? It should be fastest because it is the least overhead, and safe because postgres does it's own write-order guaranteeing through fsync(). You should also mount the FS with the 'noatime' option. But.... For some workloads, there are tests showing that 'data=journal' can be the fastest! This is because although the data is written twice (once to the journal, and then to its real location on disk) in this mode data is written _sequentially_ to the journal, and later written out to its destination, which may be at a quieter time. There's a discussion (based around 7.2) here: http://www.kerneltraffic.org/kernel-traffic/kt20020401_160.txt M
