From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bill Davidsen Subject: Re: Performance Characteristics of All Linux RAIDs (mdadm/bonnie++) Date: Wed, 28 May 2008 19:00:29 -0400 Message-ID: <483DE40D.8090608@tmr.com> References: <95711f160805280934y77ed7d91tec5aeb531bf8013c@mail.gmail.com> <20080528195752.0cdcbc6d@core> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20080528195752.0cdcbc6d@core> Sender: linux-raid-owner@vger.kernel.org To: Alan Cox Cc: =?UTF-8?B?SmVucyBCw6Rja21hbg==?= , Justin Piszcz , linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, xfs@oss.sgi.com List-Id: linux-raid.ids Alan Cox wrote: > On Wed, 28 May 2008 18:34:00 +0200 > "Jens B=C3=A4ckman" wrote: >=20 >> On Wed, May 28, 2008 at 10:53 AM, Justin Piszcz wrote: >>> Results: >>> >>> http://home.comcast.net/~jpiszcz/raid/20080528/raid-levels.html >>> http://home.comcast.net/~jpiszcz/raid/20080528/raid-levels.txt >> Either the RAID 1 read speed must be wrong, or something is odd in t= he >> Linux implementation. There's six drives that can be used for readin= g >> at the same time, as they contain the very same data. 63MB/s >> sequential looks like what you would get from a single drive. >=20 > Which is fairly typical of a cheap desktop PC where the limitation is= the > memory and PCI bridge as much as the drive. >=20 I really don't think that's any part of the issue, the same memory and=20 bridge went 4-5x faster in other read cases. The truth is that the=20 raid-1 performance is really bad, and it's the code causing it AFAIK. I= f=20 you track the actual io it seems to read one drive at a time, in order,= =20 without overlap. --=20 Bill Davidsen "We have more to fear from the bungling of the incompetent than from the machinations of the wicked." - from Slashdot -- 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