From owner-freebsd-current@FreeBSD.ORG Fri Dec 25 11:44:44 2009 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id E40C31065670; Fri, 25 Dec 2009 11:44:44 +0000 (UTC) (envelope-from phk@critter.freebsd.dk) Received: from phk.freebsd.dk (phk.freebsd.dk [130.225.244.222]) by mx1.freebsd.org (Postfix) with ESMTP id A80688FC19; Fri, 25 Dec 2009 11:44:44 +0000 (UTC) Received: from critter.freebsd.dk (critter.freebsd.dk [192.168.61.3]) by phk.freebsd.dk (Postfix) with ESMTP id 9945F7E995; Fri, 25 Dec 2009 11:44:43 +0000 (UTC) Received: from critter.freebsd.dk (localhost [127.0.0.1]) by critter.freebsd.dk (8.14.3/8.14.3) with ESMTP id nBPBjLS0027417; Fri, 25 Dec 2009 11:45:21 GMT (envelope-from phk@critter.freebsd.dk) To: Thomas Backman From: "Poul-Henning Kamp" In-Reply-To: Your message of "Fri, 25 Dec 2009 12:22:08 +0100." <469FFFC8-514B-41B9-AEEC-E4B7AB6CB886@exscape.org> Date: Fri, 25 Dec 2009 11:45:20 +0000 Message-ID: <27416.1261741520@critter.freebsd.dk> Sender: phk@critter.freebsd.dk Cc: Alexander Motin , FreeBSD-Current , freebsd-arch@freebsd.org Subject: Re: File system blocks alignment X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 25 Dec 2009 11:44:45 -0000 In message <469FFFC8-514B-41B9-AEEC-E4B7AB6CB886@exscape.org>, Thomas Backman w rites: >On Dec 25, 2009, at 11:58 AM, Alexander Motin wrote: >They don't expose this to the OS, though (not by default, anyway), but = >chop it up into 8 512-byte sectors for compatibility reasons. >Just thought I'd point that out - I'm not even sure if you can get them = >to *not* do the compatibility thing and expose 4k-sized sectors. While that is true, it is worth noting that the same Windows-compat idioty is what doomed the world to RAID5 instead of RAID3. The recent article in Queue Magazine shows how deeply ingrained the 512byte mindset has become: The author goes to great lengths to praise RAID6 and higher for their ability to have multiple bit ECC without ever recognizing (author not knowing ?) that RAID3 has had this ability from day one. UFS runs incredibly well on 4k blocks, and we should exploit that to the fullest extent, and if we really want to jerk chains, we should push RAID3 in 4+2 and 8+3 configs aggressively, it performs great, both under read and write, and Windows cannot do it. Poul-Henning PS: Merry X-mas everybody! -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.