From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roberto Spadim Subject: Re: What's the typical RAID10 setup? Date: Mon, 31 Jan 2011 13:37:04 -0200 Message-ID: References: <20110131152151.GD7861@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: Sender: linux-raid-owner@vger.kernel.org To: Linux-RAID List-Id: linux-raid.ids the main problem is, you can lose one disk if you lose any disk, you should replace all disks and raid1 allow you to make it online (without shutdown your server) that's the main use of raid1 (replica/mirror/redundance) 2011/1/31 Roberto Spadim : > the only way to make it safer, is put more devices on raid1 > for example: > disks=3D6 (was wrong on last email) > raid0=3D 1-2(a) 3-4(b) 5-6(c) > raid1=3D a,b,c > > or > raid1=3D1-2-3(a) 4-5-6(b) > raid0=3Da,b > now you can loose tree disks > > 2011/1/31 Roberto Spadim : >> rewriting.. >> using raid10 or raid01 you will have problems if you lose 2 drives t= oo... >> if you lose two raid 1 devices you loose raid 1... >> see: >> >> disks=3D4 >> RAID 1+0 >> raid1=3D 1-2(A) =A0; 3-4(B); 5-6(C) >> raid0=3D A-B-C >> if you lose (A,B or C) your raid0 stop >> >> RAID 0+1 >> raid0=3D 1-2-3(A) =A0; 4-5-6(B) >> raid1=3D A-B >> if you lose (1,4 OR 1,5 OR 1,6 OR 2,4 OR 2,5 OR 2,6 OR 3,4 OR 4,5 OR >> 4,6) your raid0 stop >> >> using raid1+0 or raid0+1 you can't lose two disks... >> >> >> >> 2011/1/31 Roberto Spadim : >>> do you have a faster array using raid0+1 or raid1+0? >>> >>> 2011/1/31 Roberto Spadim : >>>> hum that's right, >>>> but not 'increase' (only if you compare raid0+1 betwen raid1+0) us= ing >>>> raid1 and after raid0 have LESS point of fail between raid 0 and a= fter >>>> raid 1, since the number of point of fail is proportional to numbe= r of >>>> raid1 devices. >>>> >>>> 2011/1/31 Robin Hill : >>>>> On Mon Jan 31, 2011 at 01:00:13PM -0200, Roberto Spadim wrote: >>>>> >>>>>> i think make two very big raid 0 >>>>>> and after raid1 >>>>>> is better >>>>>> >>>>> Not really - you increase the failure risk doing this. =A0With th= is setup, >>>>> a single drive failure from each RAID0 array will lose you the en= tire >>>>> array. =A0With the reverse (RAID0 over RAID1) then you require bo= th drives >>>>> in the RAID1 to fail in order to lose the array. =A0Of course, wi= th a 4 >>>>> drive array then the risk is the same (33% with 2 drive failures)= but >>>>> with a 6 drive array it changes to 60% for RAID1 over RAID0 versu= s 20% >>>>> for RAID0 over RAID1. >>>>> >>>>> Cheers, >>>>> =A0 =A0Robin >>>>> -- >>>>> To unsubscribe from this list: send the line "unsubscribe linux-r= aid" in >>>>> the body of a message to majordomo@vger.kernel.org >>>>> More majordomo info at =A0http://vger.kernel.org/majordomo-info.h= tml >>>>> >>>> >>>> >>>> >>>> -- >>>> Roberto Spadim >>>> Spadim Technology / SPAEmpresarial >>>> >>> >>> >>> >>> -- >>> Roberto Spadim >>> Spadim Technology / SPAEmpresarial >>> >> >> >> >> -- >> Roberto Spadim >> Spadim Technology / SPAEmpresarial >> > > > > -- > 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