Thanks for your insights Baruch. The crc count did not increase any further - so this was probably just small oddity (was zero before when the write-same issue already happened). The real issue however does persist. I found a way to reliably trigger the log messages. Using a program called checksum over a photo share (which does a lot of reads and one write per file). With that in place I switched to the 3.4.38 kernel, with which I'm unable to trigger the problem. I will leave the system at that for now, and try to reproduce it on my testing machine to see, whether c8dc9c6 md: raid1,10: Handle REQ_WRITE_SAME flag in write bios works for me. If c8dc9c6 does the trick, it would still be interesting to know why and how this triggered i/o errors, the strange log message from lsi and 'Resets Between Cmd Acceptance and Completion' as one of the drives says. Would that mean the driver/firmware from lsi is issuing or passing on commands to the drive which it does not understand or can't process? --- Matthias -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html