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 <jd_hardcastle@xxxxxxxxx> wrote: > > > > --- On Wed, 16/9/09, Majed B. <majedb@xxxxxxxxx> wrote: > >> From: Majed B. <majedb@xxxxxxxxx> >> Subject: Re: LVM and Raid5 >> To: "Goswin von Brederlow" <goswin-v-b@xxxxxx> >> Cc: "Linux Raid Study" <linuxraid.study@xxxxxxxxx>, linux-raid@xxxxxxxxxxxxxxx >> 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 >> <goswin-v-b@xxxxxx> >> wrote: >> > Linux Raid Study <linuxraid.study@xxxxxxxxx> >> 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 >> > Goswin >> > -- >> > To unsubscribe from this list: send the line >> "unsubscribe linux-raid" in >> > the body of a message to majordomo@xxxxxxxxxxxxxxx >> > More majordomo info at http://vger.kernel.org/majordomo-info.html >> > >> >> >> >> -- >> Majed 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 underlying md is faster so should the LV's? > > ----------------------- > N: Jon Hardcastle > E: Jon@xxxxxxxxxxxxxxx > 'Do not worry about tomorrow, for tomorrow will bring worries of its own.' > ----------------------- > > > > -- Majed B. -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
