From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roberto Spadim Subject: Re: wish for Linux MD mirrored raid types Date: Fri, 6 May 2011 12:34:36 -0300 Message-ID: References: <20110506071752.GA22063@www2.open-std.org> <20110506133159.30c66519@natsu> <20110506090345.GA22245@www2.open-std.org> <4DC3BDD9.1060300@abpni.co.uk> <20110506094102.GC22245@www2.open-std.org> <20110506155059.6f82cbeb@natsu> <4DC3C804.6080200@abpni.co.uk> <20110506132739.GA22689@www2.open-std.org> <4DC3FF4C.5090502@meetinghouse.net> <20110506152405.GB22964@www2.open-std.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20110506152405.GB22964@www2.open-std.org> Sender: linux-raid-owner@vger.kernel.org To: =?ISO-8859-1?Q?Keld_J=F8rn_Simonsen?= Cc: Miles Fidelman , linux-raid@vger.kernel.org List-Id: linux-raid.ids hum, i asked this question one time, the point is: raid1 code is very easy raid10 code is more complex easy =3D faster, less memory, less cpu complex =3D faster?, more memory? more cpu? check others raid system (freebsd, netbsd) and check how they do... 2011/5/6 Keld J=F8rn Simonsen : > On Fri, May 06, 2011 at 10:01:48AM -0400, Miles Fidelman wrote: >> Keld J=F8rn Simonsen wrote: >> >>As you say, RAID10,near on four disks is pretty much identical to >> >>RAID1+0 - i.e., a stripe of two normal RAID1 pairs. >> >> >> >> I don't that's exactly right. =A0At least as I understand it: >> >> - RAID1+0 (and RAID0+1) nests things - you start with two sets of RA= ID1 >> mirrors, then stripe across them (or vice versa) - it's a nested set= of >> steps >> >> - md RAID10 provides both mirroring and striping, but it's a more >> integrated function - (from the man page) "RAID10 provides a combina= tion >> of RAID1 and RAID0, and sometimes known as RAID1+0. Every datablock = is >> duplicated some number of times, and the resulting collection of >> datablocks are distributed over multiple drives." - but there isn't = an >> inherent nesting in the process (i.e., no two disks are copies of ea= ch >> other, and md RAID10 will work over odd numbers of drives) > > Yes, you are right, RAID1+0 is nested, while Linux MD raid10 is not. > But the data layout of Linux MD RAID1+0 and Linux MD > RAID10,near is almost identical. > > keld > -- > 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 > --=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