Alan Stern wrote: > On Wed, 24 Dec 2008, Ludovico Cavedon wrote: >> -it is happening also with 2.6.28-rc8 (which should have the patch, right?) > > What patch? Do you mean the patch at the end of that email thread? It > affects only Argosy USB drives, not your Western Digital. I thought also patches http://marc.info/?l=linux-scsi&m=122443015406309&w=2 were included, but later I realized I was wrong. I have patched my kernel with them, and now I/O errors get reported! >> I am not able to understand if this is HD problem or a kernel problem. I > > Partly both. The HD (or more likely, its USB interface) is responsible > for sending those unnecessary empty sense records. The kernel is > responsible for not reporting an I/O error (assuming an error actually > did take place). I think I found out what is happening on the HD side. The SMART self test fails with a read error. The SMART log reports uncorrectable read errors. However Reallocated_Event_Count is 0. Searching on the web, looks like that these sectors have bad ECC, so the cause a read error, however they are not bad sectors. Is this correct? My question is: how can this happen? and not just one sector, but at least a dozen! Bad HD? (it's new! 93 hrs of activity so far!) >> am able to replicate it: >> -2.6.28-rc8 vanilla kernel >> -2.6.27 ubuntu (intrepid) kernel > > 2.6.27 doesn't go into an endless loop? This may indicate that > eventually the drive stops sending the Check Condition status. You are right. Most of the read attempts succeed after a a while. However I found one sector that is causing an endless loop on 2.6.27 and unpatched 2.6.28-rc8 > It would help to see the dmesg log for when one of these errors occurs. There are no additional messages. However here it is: http://pastebin.com/mcfd54a3 > It would also help to know what happens under Windows. Do the same > "empty sense" errors occur? If they do, how does Windows handle them? I can try to use usb snoopy to log usb traffic under windows. Do you know how I can ask Windows "read sector X"? Thank you for your help, Merry Christmas! Ludovico -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
