From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: [RFC 1/2]raid1: only write mismatch sectors in sync Date: Thu, 18 Oct 2012 12:29:59 +1100 Message-ID: <20121018122959.10bb6c87@notabene.brown> References: <20120731155304.11c40f9b@notabene.brown> <20120911105908.51681433@notabene.brown> <20120912052941.GA15827@kernel.org> <20120918145710.55394bd4@notabene.brown> <20120919055106.GA1305@kernel.org> <20120919171646.6bc35ba5@notabene.brown> <20120920015655.GB6798@kernel.org> <20121017051113.GA17821@kernel.org> <20121018095601.7aa3238b@notabene.brown> <20121018011735.GA1448@kernel.org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/G.=o7qgowu6DJwA+Iz+oeJV"; protocol="application/pgp-signature" Return-path: In-Reply-To: <20121018011735.GA1448@kernel.org> Sender: linux-raid-owner@vger.kernel.org To: Shaohua Li Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids --Sig_/G.=o7qgowu6DJwA+Iz+oeJV Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Thu, 18 Oct 2012 09:17:35 +0800 Shaohua Li wrote: =20 > > > Neil, > > > any further comments on this? This is a usable feature, I hope we can= have some > > > agreements. > >=20 > > You still haven't answered my main question, which possibly means I hav= en't > > asked it very clearly. > >=20 > > You are saying that this new behaviour should not be the default and I = think > > I agree. > > So the question is: how it is selected? > >=20 > > You cannot expect the user to explicitly enable it any time a resync or > > recovery starts that should use this new feature. You must have some > > automatic, or semi-automatic, way for the feature to be activated, othe= rwise > > it will never be used. > >=20 > > I'm not asking "when should the feature be used" - you've answered that > > question a few time and it really isn't an issue. > > The question it "What it the exact process by which the feature is turn= ed on > > for any particular resync or recovery?" >=20 > So you worried about users don't know how to correctly select the feature= . An > experienced user knows this, the usage scenario I mentioned describes how= to do > the decision. For example, a resync after system crash should enable the > feature. I admit an inexperienced user doesn't know how to select it, but= this > isn't a big problem to me. There are a lot of tunables in the kernel (eve= n MD), > which can significantly impact kernel behavior. These tunables are just f= or > experienced users. >=20 > Thanks, > Shaohua You still aren't answering my question. What exactly, precisely, specifically, will an "experienced user" do? NeilBrown --Sig_/G.=o7qgowu6DJwA+Iz+oeJV Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.18 (GNU/Linux) iQIVAwUBUH9blznsnt1WYoG5AQIQHg//dPd86NoPenqJuccOdx1WXSv6TSdd6p+1 ujOgJgE8IWi7K8fCmu2W1Hm3R+oytvLUWF6Nt6ZfANXdQ6h/0IbkOw6+Enr0yFls CmDikrYQLyHrsPXqLi1QRNRANEiPD+MtKagKqvYabvRNPyPgzz7iNOHnwro3ITya A9LSaQvv+TF3Tl3QbObbsW3Qf82Hn9TbVy3LmCCOgynzCNjZT+ClW3m/Hv8oLj0V 1/zrfuefi2V8EXkLN10/jbI7GRURv5V32LauZF3puY55y/JO6+DWlrclIGxB5dbe ABdXJAbD5SwuMbrXO7cpgMVkNW9T9UDCYWNLlsjnk3BWfalvRukzB3B12aAcElUT UMqVUKPaYNV3WY5Ne4JS+dkxdbQr4El9Kt6sqZ3XOx4MHrVoPVGDdD7pW8JGpISo 6hOtOJQF4ngQ2xiGkbu0qO24zfn/UCZFi7BviuzZoJq3FraOdTk/3DPfyGioVNGi NNIPzGw2XCi1dhiJ0BUR3n4V7Tkc+tc1LxUtZ5p3TjjU18vcyvla7t8+gYPlY1tw SrzYKziI57EUgrST19Rt14iuAR3iW12u6/KQNGU9oY7g2lA7cN2Trl6hTPZGTloq NsUiq0IYLsqf5qu3Vgy4NAnta+PtVlc/OGzpKqPbhTWcaADnk8N/FJtZdxL7THoI gYnhsgnv5NI= =9Bxs -----END PGP SIGNATURE----- --Sig_/G.=o7qgowu6DJwA+Iz+oeJV--