From mboxrd@z Thu Jan 1 00:00:00 1970 From: Al Boldi Subject: Re: RAID0 performance question Date: Sun, 27 Nov 2005 18:39:16 +0300 Message-ID: <200511271839.16480.a1426z@gawab.com> References: <437E2CB6.2030903@xss.co.at> <015c01c5f292$57e0e270$0400a8c0@dcccs> <17288.61257.912938.278958@cse.unsw.edu.au> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <17288.61257.912938.278958@cse.unsw.edu.au> Content-Disposition: inline Sender: linux-raid-owner@vger.kernel.org To: JaniD++ Cc: linux-raid@vger.kernel.org, Neil Brown List-Id: linux-raid.ids Neil Brown wrote: > On Saturday November 26, djani22@dynamicweb.hu wrote: > > > > The cat /dev/nb# >/dev/null makes ~ 350 Mbit/s on each nodes. Why is this so slow? Or is this the max node-HD throughput? What's the node HW config? > > The cat /dev/nb0 + nb1 + nb2 + nb3 in one time parallel makes ~ 780-800 > > Mbit/s. - i think this is my network bottleneck. How much do you get w/ nb0+1,2,3 and nb0+1+2,3 respectively? > > But the cat /dev/md31 >/dev/null (RAID0, the sum of 4 nodes) only makes > > ~450-490 Mbit/s, and i dont know why.... > > > > Somebody have an idea? :-) > > Try increasing the read-ahead setting on /dev/md31 using 'blockdev'. > network block devices are likely to have latency issues and would > benefit from large read-ahead. Also try larger chunk-size ~4mb. -- Al