From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Majed B." Subject: Re: raid10 layout for 2xSSDs Date: Tue, 17 Nov 2009 00:19:25 +0300 Message-ID: <70ed7c3e0911161319u5d6fd6c7vf9d41fa2da96801b@mail.gmail.com> References: <1258381745.31633.35.camel@localhost> <7bc80d500911160808o4ca4d335gdeeb50fff61b2149@mail.gmail.com> <1258405373.31633.49.camel@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <1258405373.31633.49.camel@localhost> Sender: linux-raid-owner@vger.kernel.org To: LinuxRaid List-Id: linux-raid.ids Wouldn't you be getting the same data twice? or would the kernel request the half the data from one disk & the other from the other disk? (file1-> chunk1@disk1 & chunk2@disk2, chunk3@disk1 & chunk3@disk2) On Tue, Nov 17, 2009 at 12:02 AM, Kasper Sandberg wrote: > > On Mon, 2009-11-16 at 08:08 -0800, Christopher Chen wrote: > > On Mon, Nov 16, 2009 at 6:29 AM, Kasper Sandberg wrote: > > > Hello. > > > > > > I've been wanting to create a raid10 array of two SSDs, and I am > > > currently considering the layout. > > > > > > As i understand it, near layout is similar to raid1, and will onl= y > > > provide a speedup if theres 2 reads at the same time, not a singl= e > > > sequential read. > > > > > > so the choice is really between far and offset. As i see it, the > > > difference is, that offset tries to reduce the seeking for writin= g > > > compared to far, but that if you dont consider the seeking penalt= y, > > > average sequential write speed across the entire array should be = roughly > > > the same with offset and far, with offset perhaps being a tad mor= e > > > "stable", is this a correct assumption? if it is, that would mean= offset > > > provides a higher "garantueed" speed than far, but with a lower m= aximum > > > speed. > > > > Do you plan to have more than two devices in the array? Raid 10 isn= 't > no > > magic. If you don't have more than do devices, I suppose your seek > > time might be half for reads (and higher for writes), but you won't= be > > able to do any striping. > > > > I'm a bit confused as to the number of people popping in recently > > wanting to run raid 10 on two disk "arrays". > to get the doubled singlestream sequential read performance.. > > > > cc > > > > -- > 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 =C2=A0http://vger.kernel.org/majordomo-info.ht= ml -- =C2=A0 =C2=A0 =C2=A0 Majed B. -- 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