From owner-freebsd-hackers@FreeBSD.ORG Mon Sep 23 16:38:53 2013 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTP id 02CFACCD; Mon, 23 Sep 2013 16:38:53 +0000 (UTC) (envelope-from dan@dan.emsphone.com) Received: from email2.allantgroup.com (email2.emsphone.com [199.67.51.116]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id AB92529B4; Mon, 23 Sep 2013 16:38:51 +0000 (UTC) Received: from dan.emsphone.com (dan.emsphone.com [172.17.17.101]) by email2.allantgroup.com (8.14.5/8.14.5) with ESMTP id r8NGciv1041571 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Mon, 23 Sep 2013 11:38:44 -0500 (CDT) (envelope-from dan@dan.emsphone.com) Received: from dan.emsphone.com (smmsp@localhost [127.0.0.1]) by dan.emsphone.com (8.14.7/8.14.6) with ESMTP id r8NGcifo033918 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Mon, 23 Sep 2013 11:38:44 -0500 (CDT) (envelope-from dan@dan.emsphone.com) Received: (from dan@localhost) by dan.emsphone.com (8.14.7/8.14.7/Submit) id r8NGciBP033917; Mon, 23 Sep 2013 11:38:44 -0500 (CDT) (envelope-from dan) Date: Mon, 23 Sep 2013 11:38:44 -0500 From: Dan Nelson To: Jia-Shiun Li Subject: Re: What's the state of AF-4Kn support? Message-ID: <20130923163844.GE97298@dan.emsphone.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-OS: FreeBSD 9.1-STABLE User-Agent: Mutt/1.5.21 (2010-09-15) X-Virus-Scanned: clamav-milter 0.97.8 at email2.allantgroup.com X-Virus-Status: Clean X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.7 (email2.allantgroup.com [172.17.19.78]); Mon, 23 Sep 2013 11:38:44 -0500 (CDT) X-Spam-Status: No, score=-3.9 required=5.0 tests=ALL_TRUSTED,BAYES_00, RP_MATCHES_RCVD autolearn=ham version=3.3.2 X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on email2.allantgroup.com X-Scanned-By: MIMEDefang 2.73 Cc: Ravi Pokala , 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 16:38:53 -0000 In the last episode (Sep 23), Jia-Shiun Li said: > On Wed, Sep 18, 2013 at 10:49 PM, Ravi Pokala wrote: > > 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. I don't think there are any yet, but some SATA->USB drive enclosures will present a 4Kn drive to the host if the physical drive is 512e. The Seagate Backup Plus does this at least. It lets you continue to use MBR-based partitioning and still access all of a 4TB disk. Unfortunately, since both GPT and MBR work off of block offsets, partitions created in one mode won't work in the other, so you can't just swap a disk in and out of the enclosure without (carefully) repartitioning. -- Dan Nelson dnelson@allantgroup.com