From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Majed B." Subject: Re: LVM and Raid5 Date: Wed, 16 Sep 2009 14:00:30 +0300 Message-ID: <70ed7c3e0909160400k578741e7ue687d8fd983d0d12@mail.gmail.com> References: <70ed7c3e0909160320j68c792d2g8ba01ac3c34eaae5@mail.gmail.com> <894436.58276.qm@web51307.mail.re2.yahoo.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <894436.58276.qm@web51307.mail.re2.yahoo.com> Sender: linux-raid-owner@vger.kernel.org To: Jon@ehardcastle.com Cc: Goswin von Brederlow , Linux Raid Study , linux-raid@vger.kernel.org List-Id: linux-raid.ids I tested with both dd and hdparm, and in both cases, md0 proved to be much faster than the LV itself. On Wed, Sep 16, 2009 at 1:33 PM, Jon Hardcastle wrote: > > > > --- On Wed, 16/9/09, Majed B. wrote: > >> From: Majed B. >> Subject: Re: LVM and Raid5 >> To: "Goswin von Brederlow" >> Cc: "Linux Raid Study" , linux-raid@vger.= kernel.org >> Date: Wednesday, 16 September, 2009, 11:20 AM >> Hello, >> >> I'm the one who ran those tests with LVM vs. RAID5 and I >> think I have >> faced speed difference because I have disks of varying >> speeds >> (different models and vendors), and I believe that LVM gets >> crippled >> down to the speed of the slowest disk. >> >> On Wed, Sep 16, 2009 at 1:09 PM, Goswin von Brederlow >> >> wrote: >> > Linux Raid Study >> writes: >> > >> >> Hello: >> >> >> >> Has someone experimented with LVM and Raid5 >> together (on say, 2.6.27)? >> >> Is there any performance drop if LVM/Raid5 are >> combined vs Raid5 alone? >> >> >> >> Thanks for your inputs! >> > >> > Has always worked perfectly for me and i can't say I >> noticed any >> > performance change. >> > >> > MfG >> > =C2=A0 =C2=A0 =C2=A0 =C2=A0Goswin >> > -- >> > 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= =2Ehtml >> > >> >> >> >> -- >> =C2=A0 =C2=A0 =C2=A0=C2=A0=C2=A0Majed B. >> -- > > Is that the case even if a dd read from say md4 is much, much faster = that he lvm's that are based on md4? Surely if the read from the underl= ying md is faster so should the LV's? > > ----------------------- > N: Jon Hardcastle > E: Jon@eHardcastle.com > 'Do not worry about tomorrow, for tomorrow will bring worries of its = own.' > ----------------------- > > > > --=20 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