From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roberto Spadim Subject: Re: What's the typical RAID10 setup? Date: Thu, 3 Feb 2011 01:17:44 -0200 Message-ID: References: <4D4883A3.6030605@hardwarefreak.com> <20110202092508.GA18517@cthulhu.home.robinhill.me.uk> <20110202194456.GA15080@www2.open-std.org> <4D4A1B80.2090203@hardwarefreak.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Stan Hoeppner Cc: =?ISO-8859-1?Q?Keld_J=F8rn_Simonsen?= , Jon Nelson , linux-raid@vger.kernel.org List-Id: linux-raid.ids could we implement first a round robin, and after try another algorithm (time based)? with round robin many problems for ssd can be solved, near head don't help ssd disks since they don't have head, and sequencial read rate is near random read rate 2011/2/3 Roberto Spadim : >> Anyone who would mix drives of such disparate spindle speeds within = the same >> array is not concerned with performance. =A0Anyone who has read enou= gh to create >> their first array knows better than to do this. > i don't think that... let's talk about internet link? we can have two > internet links (1 radio, 1 adsl or another), with linux i can load > balance based on network band use, round robin, and many others ideas > it's same for raid1, except, write speed =3D slowest write speed, for > read we can get highers speed (with raid1 we can have same speed than > raid0, or, we should...) > >> Why waste effort to optimize such a horrible design decision? > a horrible design decision: > two 1TB ssd with 1,5GB/s and two 1TB =A0ssd with 2,0GB/s (can be from > texas... or ocz...) > using raid1, it's a horrible design? > or... for hard disks > two 1tb sas with 300MB/s and two 1tb sas with 250MB/s (i never get > more speed than 300mb/s with hard disks) > is it a horrible design? > >> This is just silly. > no, it's a option, we could use round robin, near head, and another > read balance algorithms, the closest to read world the faster we get > > now it's true for raid1: write speed is poor (that's why we use raid1= 0) > but read can be as fast as raid0 .... even faster since all disks hav= e > the same information... what we need is a good read balance algorithm > (i think for a non balanced array, a time based is the best option...= ) > > 2011/2/3 Stan Hoeppner : >> Roberto Spadim put forth on 2/2/2011 2:28 PM: >> >>> i don=B4t think, since head, is just for hard disk (rotational) not= for >>> solid state disks, let=B4s not talk about ssd, just hard disk? a ra= id >>> with 5000rpm =A0and 10000rpm disk, we will have better i/o read wit= h >> >> Anyone who would mix drives of such disparate spindle speeds within = the same >> array is not concerned with performance. =A0Anyone who has read enou= gh to create >> their first array knows better than to do this. >> >> Why waste effort to optimize such a horrible design decision? >> >>> 10000rpm ? we don=B4t know the model of i/o for that device, but >>> probally will be faster, but when it=B4s busy we could use 5000rpm.= =2E. >>> that=B4s the point, just closest head don=B4t help, we need know wh= at=B4s >>> the queue (list of i/o being processed) and the time to read the >>> current i/o >> >> This is just silly. >> >> -- >> Stan >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-raid= " in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at =A0http://vger.kernel.org/majordomo-info.html >> > > > > -- > Roberto Spadim > Spadim Technology / SPAEmpresarial > --=20 Roberto Spadim Spadim Technology / SPAEmpresarial -- 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