From owner-freebsd-fs@FreeBSD.ORG Fri Mar 26 16:15:42 2010 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id C25FD1065676 for ; Fri, 26 Mar 2010 16:15:42 +0000 (UTC) (envelope-from jdc@koitsu.dyndns.org) Received: from qmta12.westchester.pa.mail.comcast.net (qmta12.westchester.pa.mail.comcast.net [76.96.59.227]) by mx1.freebsd.org (Postfix) with ESMTP id 708828FC1F for ; Fri, 26 Mar 2010 16:15:42 +0000 (UTC) Received: from omta23.westchester.pa.mail.comcast.net ([76.96.62.74]) by qmta12.westchester.pa.mail.comcast.net with comcast id xnLl1d0011c6gX85CsFive; Fri, 26 Mar 2010 16:15:42 +0000 Received: from koitsu.dyndns.org ([98.248.46.159]) by omta23.westchester.pa.mail.comcast.net with comcast id xsK31d0033S48mS3jsK3N3; Fri, 26 Mar 2010 16:19:04 +0000 Received: by icarus.home.lan (Postfix, from userid 1000) id F35ED9B436; Fri, 26 Mar 2010 09:15:39 -0700 (PDT) Date: Fri, 26 Mar 2010 09:15:39 -0700 From: Jeremy Chadwick To: Kirk McKusick Message-ID: <20100326161539.GA10618@icarus.home.lan> References: <4BACB3F5.7010905@freebsd.org> <201003261528.o2QFSAuI037251@chez.mckusick.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201003261528.o2QFSAuI037251@chez.mckusick.com> User-Agent: Mutt/1.5.20 (2009-06-14) Cc: freebsd-fs@freebsd.org, Andriy Gapon , freebsd-geom@freebsd.org Subject: Re: g_vfs_open and bread(devvp, ...) X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 26 Mar 2010 16:15:42 -0000 On Fri, Mar 26, 2010 at 08:28:10AM -0700, Kirk McKusick wrote: > I have reviewed your change and I believe that your analysis is > correct. I am in agreement with your making the change. > > As disk sector sizes will be growing in the near future, it would > be desirable to get away from having DEV_BSIZE hard-coded. But as > you note, that is a far bigger change than this one. I should note that they already have grown: Western Digital, as of a few months ago, began shipping drives that use 4KByte sectors. They're known as the "EARS" drives, due to their model string ending with "EARS": WD20EARS: http://www.wdc.com/en/products/Products.asp?DriveID=773 WD15EARS: http://www.wdc.com/en/products/products.asp?driveid=772 WD10EARS: http://www.wdc.com/en/products/products.asp?driveid=763 (I should warn folks these are Caviar Green drives, which may suffer from excessive Load Cycles (parking/unparking actuator arm). I don't have one of these drives so I can't validate if the issue happens on this model or not) A discussion and an including an incredibly cheesy video review are below. The video review does discuss the 4KB sector size, in addition to jumpers that revert the drive to using 512-byte sectors for older OSes such as Windows XP -- and presumably FreeBSD. http://www.tomshardware.com/reviews/wd-4k-sector,2554.html http://www.youtube.com/watch?v=QeFj2QTaA3Y -- | Jeremy Chadwick jdc@parodius.com | | Parodius Networking http://www.parodius.com/ | | UNIX Systems Administrator Mountain View, CA, USA | | Making life hard for others since 1977. PGP: 4BD6C0CB |