From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christopher Chen Subject: Re: raid10 layout for 2xSSDs Date: Mon, 16 Nov 2009 08:38:34 -0800 Message-ID: <7bc80d500911160838r2c21448eyefd788e6c84c780@mail.gmail.com> References: <1258381745.31633.35.camel@localhost> <878we61oev.fsf@frosties.localdomain> <20091116163102.GB28577@cthulhu.home.robinhill.me.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20091116163102.GB28577@cthulhu.home.robinhill.me.uk> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids On Mon, Nov 16, 2009 at 8:31 AM, Robin Hill wro= te: > On Mon Nov 16, 2009 at 04:26:32PM +0100, Goswin von Brederlow wrote: > >> What I'm aiming at is that offset might better fit into erase blocks= , >> cause less internal fragmentation on the disk and give better wear >> leveling. Might improve speed and lifetime. But that is just a >> thought. Maybe test and do ask Intel (or other vendors) about it. >> > I very much doubt this will make any difference. =A0With SSDs you hav= e to > throw out any preconceptions of internal layout you may have. =A0You = have > absolutely no idea (or control of) where two consecutive blocks will > actually get written. =A0Fragmentation and seek time are thus irrelev= ant > (or uncontrollable anyway). > > I don't see how any RAID-10 layout would perform better than another > with SSDs, unless there's internal optimisations/constraints which > affect sequential reading from multiple devices. =A0I'm not aware of = any > though - RAID-10 n2 may be the same layout as RAID-1 but it's an > entirely separate piece of code. Don't forget that RAID-1 also does balanced reads. --=20 Chris Chen "The fact that yours is better than anyone else's is not a guarantee that it's any good." -- Seen on a wall -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html