You're reading the wrong numbers. Try benchmarking with PostgreSQL's pg_test_fsync or with fio with the following options: --direct=1 --sync=1 --rw=write --bs=4

You're reading the wrong numbers. Try benchmarking with PostgreSQL's pg_test_fsync or with fio with the following options: --direct=1 --sync=1 --rw=write --bs=4k Good random-write performance with 4k/8k blocks at QD1 is what matter for SSD's, not if they can write 2500MB/s to a volatile cache. Recommended read http://www.sebastien-han.fr/blog/2014/10/10/ceph-how-to-test-if-your-ssd-is-suitable-as-a-journal-device/ http://www.sebastien-han.fr/blog/2014/10/10/ceph-how-to-test...