From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Lord Subject: Re: ata_eh_link_autopsy: Bug? Date: Tue, 01 May 2012 19:52:33 -0400 Message-ID: <4FA07741.1030105@teksavvy.com> References: <4FA043BE.2010009@teksavvy.com> <4FA04714.7050602@teksavvy.com> <20120501215854.GA21677@google.com> <4FA07655.6090506@teksavvy.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from ironport-out.teksavvy.com ([206.248.143.162]:21556 "EHLO ironport-out.teksavvy.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754440Ab2EAXwe (ORCPT ); Tue, 1 May 2012 19:52:34 -0400 In-Reply-To: <4FA07655.6090506@teksavvy.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Tejun Heo Cc: IDE/ATA development list 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