From owner-freebsd-hackers@FreeBSD.ORG Mon Sep 23 06:23:11 2013 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTP id 71DC7CB3; Mon, 23 Sep 2013 06:23:11 +0000 (UTC) (envelope-from jiashiun@gmail.com) Received: from mail-ve0-x233.google.com (mail-ve0-x233.google.com [IPv6:2607:f8b0:400c:c01::233]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 215A821A9; Mon, 23 Sep 2013 06:23:11 +0000 (UTC) Received: by mail-ve0-f179.google.com with SMTP id c14so1907260vea.38 for ; Sun, 22 Sep 2013 23:23:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-type; bh=wEkIsMFCtxXIrwTeLqXlyqA1Z/cuqqXqk8vEr9pC038=; b=IL9OBphDIhrHBprUZYESgZXS96EIgoFdnHpWx/8u2C8gUYdn7IK2tBVcnPMZBVvpbK m15ky0Yljf2K88IGDfLlTj65RhJ0Lwb16GS1zMhejXkHUOXdP0bzNbNoxeIO+xLsq+WA rEgS0qxCln3Jf3UcgcbM9wUpSvodHD8vq69BBPyzAufNl7lavWQQcGxRQ7sU6vGoO51q Wdt8OMSpS3ZXqJm+q6gnbVsNNHPAGoGY1UlQHdqyYQ9g+EYQN7OxIQzpZl6NynmkJN6n ZL4rKWpvgubEjjsLrJLmQAwC/zF0Oc6p6gfaMB70nM+iHYvigFadhcn7lbFvhH1CoTQk CF2g== X-Received: by 10.220.237.208 with SMTP id kp16mr20500450vcb.4.1379917390166; Sun, 22 Sep 2013 23:23:10 -0700 (PDT) MIME-Version: 1.0 Received: by 10.58.225.34 with HTTP; Sun, 22 Sep 2013 23:22:40 -0700 (PDT) In-Reply-To: References: From: Jia-Shiun Li Date: Mon, 23 Sep 2013 14:22:40 +0800 Message-ID: Subject: Re: What's the state of AF-4Kn support? To: Ravi Pokala Content-Type: text/plain; charset=UTF-8 Cc: freebsd-hackers@freebsd.org, "freebsd-hardware@freebsd.org" X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 23 Sep 2013 06:23:11 -0000 On Wed, Sep 18, 2013 at 10:49 PM, Ravi Pokala wrote: > > What you describe is the 'AF-512e' format - 4KB physical sectors > *emulating* 512B logical sectors. See [ > https://en.wikipedia.org/wiki/Advanced_Format#Advanced_Format_512e ; > http://www.idema.org/?page_id=2153 ]. With AF-512e, yes, the HDD firmware > does the read/modify/write for I/Os smaller than the physical sector size. > It is intended to be a low-cost/transitional format, allowing the HDD > vendors to get the advantages of 4KB physical sectors (better error > detection/correction algorithms, better areal density => lower cost) w/o > breaking compatibility with decades of firmware and software that expect > 512B logical sectors. > > What I'm asking about is AF-4kn - 4KB *logical* as well as physical > sectors. All the enterprise HDD vendors have told us is that AF-4Kn drives > expect data IO to be 4KB, and will reject smaller transfers. (*metadata* > IO - SMART, IDENTIFY_DEVICE, READ_LOG/WRITE_LOG, etc - will remain 512B.) > > Doing some more digging, I found this post from ivoras which I missed the > first time around [ > http://ivoras.net/blog/tree/2011-01-01.freebsd-on-4k-sector-drives.html ]; > that tends to support my initial assessment - filesystem stuff should Just > Work[tm] - plus adds the detail that direct drive I/O (the example he > gives is trying to `dd' 10 bytes) will be rejected because it is smaller > than the raw-device access granularity. I've also looked at 'ata_da.c' and > see that adaregister() looks at both quirks and IDENTIFY_DEVICE data to > determine the logical block size. > > So, that leaves the bootstrap code as the remaining question-mark. Does > anyone what AF-4Kn support looks like there? > CC -hackers. Thanks for the clarification. Is there any 4Kn HDDs shopping now? I am not aware of any. BTW I believe UFS and ZFS have proper design for 4K-sectors, but FreeBSD needs some ecosystem connections to get samples early to test, incorporate supports and validate for it. Or we will need to wait until it appears on market and someone got caught into some kind of bugs. Regards, Jia-Shiun.