Date: Mon, 6 Dec 2010 20:53:27 +0100 From: Pawel Jakub Dawidek <pjd@FreeBSD.org> To: Ivan Voras <ivoras@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r216230 - head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs Message-ID: <20101206195327.GD1936@garage.freebsd.pl> In-Reply-To: <AANLkTine9rGq_cM4ruFXYq=-F7cMXcQAr-zKHuWoQs2z@mail.gmail.com> References: <201012061218.oB6CI3oW032770@svn.freebsd.org> <20101206184453.GA1936@garage.freebsd.pl> <20101206192238.GB1936@garage.freebsd.pl> <AANLkTine9rGq_cM4ruFXYq=-F7cMXcQAr-zKHuWoQs2z@mail.gmail.com>
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--SO98HVl1bnMOfKZd Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Dec 06, 2010 at 08:35:36PM +0100, Ivan Voras wrote: > Please persuade me on technical grounds why ashift, a property > intended for address alignment, should not be set in this way. If your > answer is "I don't know but you are still wrong because I say so" I > will respect it and back it out but only until I/we discuss the > question with upstream ZFS developers. No. You persuade me why changing ashift in ZFS, which, as the comment clearly states is "device's minimum transfer size" is better and not hackish than presenting the disk with properly configured sector size. This can not only affect disks that still use 512 bytes sectors, but doesn't fix the problem at all. It just works around the problem in ZFS when configured on top of raw disks. What about other file systems? What about other GEOM classes? GELI is great example here, as people use ZFS on top of GELI alot. GELI integrity verification works in a way that not reporting disk sector size properly will have huge negative performance impact. ZFS' ashift won't change that. So you should back this change out, provide technical arguments (if they exist) that this is the right solution to the problem and not "hey, here is a patch, I think it is ok". BTW. ZFS is no longer open-source if you didn't notice. --=20 Pawel Jakub Dawidek http://www.wheelsystems.com pjd@FreeBSD.org http://www.FreeBSD.org FreeBSD committer Am I Evil? Yes, I Am! --SO98HVl1bnMOfKZd Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.14 (FreeBSD) iEYEARECAAYFAkz9PzcACgkQForvXbEpPzSEVwCfSk4NS+AaEQUew40Kmgst5AFU kCYAn2sSXQOCv87u/fEyqonUfNm4/0Uv =4zHn -----END PGP SIGNATURE----- --SO98HVl1bnMOfKZd--
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