On 12-05-01 07:48 PM, Mark Lord wrote: > On 12-05-01 05:58 PM, Tejun Heo wrote: >> On Tue, May 01, 2012 at 04:27:00PM -0400, Mark Lord wrote: >>> MMmm.. even that isn't good enough, because the first ATA_QCFLAG_IO test >>> bypasses the rest of that logic and triggers unconditional retries. Ugh. >> >> Hmmm... the unconditional retry on ATA_QCFLAG_IO is intenttional so >> that known good requests from FS are guaranteed to be retried no >> matter how whacky the underlying device is. I'm not sure whether that >> was a good decision tho. Maybe we should trust the hardware a bit >> more. So, I'm not necessarily against changing it. > > With multi-terabyte drives being commonplace now, bad sectors seem > to be a more frequent occurrence than I can remember from the past. > > And when libata stumbles across a bad sector, it literally hangs the > machine for _minutes_ doing retries. I have never seen a retry make > any difference whatsoever on a bad sector read. New, old, or ancient hardware. And as a reminder to anyone else listening in, it's easier than you might think to test failure paths like this. Here, I keep a few 300GB drives around just for that purpose, and use "hdparm --make-bad-sector" on them to inject media errors at specific places on the disk or filesystem. Cheers -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
