Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752841Ab0LZWIC (ORCPT ); Sun, 26 Dec 2010 17:08:02 -0500 Received: from lo.gmane.org ([80.91.229.12]:42719 "EHLO lo.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752332Ab0LZWIA (ORCPT ); Sun, 26 Dec 2010 17:08:00 -0500 X-Injected-Via-Gmane: http://gmane.org/ To: linux-kernel@vger.kernel.org From: Niels Subject: Re: Slow disks. Date: Sun, 26 Dec 2010 23:07:45 +0100 Message-ID: References: <20101220141553.GA6088@bitwizard.nl> <20101220190630.66084e1d@neptune.home> <20101222104306.GB30941@bitwizard.nl> <4D14BB36.1030304@msgid.tls.msk.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7Bit X-Complaints-To: usenet@dough.gmane.org X-Gmane-NNTP-Posting-Host: 0x4dd52733.adsl.cybercity.dk User-Agent: KNode/0.10.9 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1633 Lines: 42 On Friday 24 December 2010 16:24, Michael Tokarev wrote: [snip] > The thing is, for these WD*EARS drivers, it is _vital_ to get > proper alignment of all partitions and operations. They've > 4Kb sectors physically but report 512bytes sectors to the OS. > It is _essential_ to ensure all partitions are aligned to the > 4Kb sectors. Be it LVM, raid-something, etc - each filesystem > must start at a 4kb boundary at least, or else you'll see > _dramatic_ write speed problems. > > So.. check the whole storage stack and ensure proper alignment > everywhere. In particular, check that your partitions are not > aligned to 63 sectors (512b), or starts at N+1 sector - the > most problematic mode for these drives. [snip] I have several of these drives, in various sizes. They seem to be aligned to 63 as you mention: Device Boot Start End Blocks Id System /dev/sda1 63 208844 104391 83 Linux /dev/sda2 208845 19759949 9775552+ 82 Linux swap / Solaris /dev/sda3 19759950 215094284 97667167+ 83 Linux /dev/sda4 215094285 781417664 283161690 83 Linux Device Boot Start End Blocks Id System /dev/sdb1 63 1953520064 976760001 83 Linux Is that bad? What can I do to repair it? What can I do to prevent it from happening again? Thanks, Niels -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/