From owner-freebsd-hackers@FreeBSD.ORG Fri Mar 27 00:18:49 2015 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id C7CA5108 for ; Fri, 27 Mar 2015 00:18:49 +0000 (UTC) Received: from ipmail05.adl6.internode.on.net (ipmail05.adl6.internode.on.net [150.101.137.143]) by mx1.freebsd.org (Postfix) with ESMTP id 59A0B137 for ; Fri, 27 Mar 2015 00:18:48 +0000 (UTC) Received: from ppp121-45-104-240.lns20.adl6.internode.on.net (HELO midget.dons.net.au) ([121.45.104.240]) by ipmail05.adl6.internode.on.net with ESMTP; 27 Mar 2015 10:48:16 +1030 Received: from [10.0.2.26] ([10.0.2.26]) (authenticated bits=0) by midget.dons.net.au (8.15.1/8.14.9) with ESMTPSA id t2R0IAX2036049 (version=TLSv1 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Fri, 27 Mar 2015 10:48:15 +1030 (CST) (envelope-from darius@dons.net.au) Subject: Re: Seagate Archive HDD Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2070.6\)) Content-Type: text/plain; charset=windows-1252 From: "O'Connor, Daniel" In-Reply-To: <5514A133.8060409@delphij.net> Date: Fri, 27 Mar 2015 10:48:10 +1030 Content-Transfer-Encoding: quoted-printable Message-Id: <88DE4F68-B05E-4E4D-8C4A-DED8147172E7@dons.net.au> References: <55148E42.80708@delphij.net> <4F65B315-5FFE-4184-91FD-C05A40E0A26E@dons.net.au> <5514A133.8060409@delphij.net> To: d@delphij.net X-Mailer: Apple Mail (2.2070.6) X-Spam-Score: -2.899 () ALL_TRUSTED,BAYES_00,URIBL_BLOCKED X-Scanned-By: MIMEDefang 2.75 on 10.0.2.1 Cc: freebsd-hackers@freebsd.org, Wojciech Puchar X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 27 Mar 2015 00:18:49 -0000 > On 27 Mar 2015, at 10:45, Xin Li wrote: > On 03/26/15 16:55, O'Connor, Daniel wrote: >>=20 >> The drive has many regions with guard bands so it doesn't have to >> rewrite the entire disk for certain writes (it may have to rewrite >> a whole band though) >=20 > That really depends on whether we can afford to lose the whole band of > (meta)data. I don't think it will lose a whole band, it journals writes, i.e. copies = the band to the journal then writes out the whole thing (modified). > That's is why I am not that optimistic about what we do nowadays, we > would need to revisit the on-disk formats with the new drives and see > if adjustments would be necessary. I agree, but it does look like they have gone to reasonable steps to = make it survive power issues. -- Daniel O'Connor "The nice thing about standards is that there are so many of them to choose from." -- Andrew Tanenbaum GPG Fingerprint - 5596 B766 97C0 0E94 4347 295E E593 DC20 7B3F CE8C