From mboxrd@z Thu Jan 1 00:00:00 1970 From: Miles Fidelman Subject: Re: wish for Linux MD mirrored raid types Date: Fri, 06 May 2011 10:01:48 -0400 Message-ID: <4DC3FF4C.5090502@meetinghouse.net> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20110506132739.GA22689@www2.open-std.org> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids 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. >> =20 I don't that's exactly right. At least as I understand it: - RAID1+0 (and RAID0+1) nests things - you start with two sets of RAID1= =20 mirrors, then stripe across them (or vice versa) - it's a nested set of= =20 steps - md RAID10 provides both mirroring and striping, but it's a more=20 integrated function - (from the man page) "RAID10 provides a combinatio= n=20 of RAID1 and RAID0, and sometimes known as RAID1+0. Every datablock is=20 duplicated some number of times, and the resulting collection of=20 datablocks are distributed over multiple drives." - but there isn't an=20 inherent nesting in the process (i.e., no two disks are copies of each=20 other, and md RAID10 will work over odd numbers of drives) Miles Fidelman --=20 In theory, there is no difference between theory and practice. In practice, there is. .... Yogi Berra -- 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