From mboxrd@z Thu Jan 1 00:00:00 1970 From: Krzysztof Halasa Subject: Re: Slow disks. Date: Mon, 27 Dec 2010 19:20:24 +0100 Message-ID: References: <20101220141553.GA6088@bitwizard.nl> <20101220190630.66084e1d@neptune.home> <20101222104306.GB30941@bitwizard.nl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from inx.pm.waw.pl ([195.116.170.130]:60445 "EHLO inx.pm.waw.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752378Ab0L0SUm (ORCPT ); Mon, 27 Dec 2010 13:20:42 -0500 In-Reply-To: (Mark Knecht's message of "Sun, 26 Dec 2010 15:38:51 -0800") Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Mark Knecht Cc: Jeff Moyer , Rogier Wolff , Greg Freemyer , Bruno =?utf-8?Q?Pr=C3=A9mont?= , linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org Mark Knecht writes: > Even when I got that part worked out I found that the drives just > didn't work well in a RAID. The mdadm list led me to believe that the > root cause was the lack of TLER in the firmware. I don't know how to > show that's true or not... But TLER only matters when the drive can't read a sector. For a normal drive which can easily read all its sectors (at least without retrying for several seconds) TLER doesn't matter. Alignment, sure. Personally I'd use whole disks (not partitions) for RAID-5 and partition the resulting /dev/md* instead, taking into account even longer "sector" size. Or better, use RAID-1 (or RAID-10) with 4 KB block fs, partition /dev/md* with 4 KB alignment, and avoid all these issues. Disks aren't that expensive now. -- Krzysztof Halasa