On 12/02/2015 07:12 PM, Dallas Clement wrote: > All measurements computed from bandwidth averages taken on 12 disk > array with XFS filesytem using fio with direct=1, sync=1, > invalidate=1. Why do you need direct=1 and sync=1 ? Have you checked an strace from the app you are trying to model that shows it uses these? > Seems incredulous!? Not with those options. Particularly sync=1. That causes an inode stats update and a hardware queue flush after every write operation. Support for that on various devices has changed over time. I suspect if you do a bisect on the kernel to pinpoint the change(s) that is doing this, you'll find a patch that closes a device-specific or filesystem sync bug or something that enables deep queues for a device. Modern software that needs file integrity guarantees make sparse use of fdatasync and/or fsync and avoid sync entirely. You'll have a more believable test if you use fsync_on_close=1 or end_fsync=1. Phil -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
