Hi guys, in the past we've used intel 520 ssds for ceph journal - this worked great and our experience was good. Now they started to replace the 520 series with their new 530. When we did we were supriced by the ugly performance and i need some days to reproduce. While O_DIRECT works fine for both and the intel ssd 530 is even faster than the 520. O_DSYNC... see the results: ~# dd if=randfile.gz of=/dev/sda bs=350k count=10000 oflag=direct,dsync 3584000000 bytes (3,6 GB) copied, 22,287 s, 161 MB/s ~# dd if=randfile.gz of=/dev/sdb bs=350k count=10000 oflag=direct,dsync 3584000000 bytes (3,6 GB) copied, 136,505 s, 26,3 MB/s I used a blocksize of 350k as my graphes shows me that this is the average workload we have on the journal. But i also tried using fio, bigger blocksize, ... it stays the same. Does anybody have an idea? Without dsync both devices have around the same performance of 260MB/s. Greets, Stefan -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
