Hi, On 11 September 2017 at 18:24, Udi-Yehuda Tamar <udi@xxxxxxxxxxxx> wrote: > I guess this question answers it's self but I'll give it a try , > Can Fio tell for sure the IO err is a data corruption ? say the drive > is busy and the read failed > but not necessarily on data corruption can Fio tell that? > I guess not! because every IO failure can be a data corruption , but I > prefer a pro answer - thx in adv. This depends on how the ioengine and the layers beneath handle it. For example the psync ioengine talks to a filesystem or block device and in Linux there's typically some sort of error handling that happens below the block layer (see http://events.linuxfoundation.org/sites/events/files/slides/SCSI-EH.pdf for how this happens for SCSI) so if the kernel (or the disk itself!) has handled the error by retrying then all userspace (and thus fio) will see is success but the latency for I/Os that get caught up might look abnormally high or the I/O will return with an error like EIO. fio can be made to abort if an I/O returns with high latency (see the max_latency option - http://fio.readthedocs.io/en/latest/fio_doc.html#cmdoption-arg-max-latency). Different I/O engines may be able to return different types of error depending on what they are talking to and what level they operate at. For example the sg ioengine sets a timeout of 30 seconds but it looks like this still makes error handling kick in (see http://sg.danny.cz/sg/p/sg_v3_ho.html#id2495241 ). I don't know if this answer is "pro" enough for you though... -- Sitsofe | http://sucs.org/~sits/ -- To unsubscribe from this list: send the line "unsubscribe fio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
