From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Kirkwood Subject: Re: RBD performance - tuning hints Date: Fri, 31 Aug 2012 20:48:34 +1200 Message-ID: <50407A62.1020208@catalyst.net.nz> References: <503F91EF.7020807@inktank.com> <1ab6cbb8-de0c-4d24-953b-98eced2f4ae2@mailpro> <24E144B8C0207547AD09C467A8259F755760304F@lisa.maurer-it.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from bertrand.catalyst.net.nz ([202.78.240.40]:53324 "EHLO mail.catalyst.net.nz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751166Ab2HaIsg (ORCPT ); Fri, 31 Aug 2012 04:48:36 -0400 In-Reply-To: <24E144B8C0207547AD09C467A8259F755760304F@lisa.maurer-it.com> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Dietmar Maurer Cc: Alexandre DERUMIER , Josh Durgin , Dieter Kasper , "ceph-devel@vger.kernel.org" , Andreas Bluemle On 31/08/12 20:11, Dietmar Maurer wrote: >>> RBD waits for the data to be on disk on all replicas. It's pretty e= asy >>> to relax this to in memory on all replicas, but there's no option f= or >>> that right now. > I thought that is dangerous, because you can loose data? > N=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BDr=EF=BF=BD=EF=BF=BDy=EF= =BF=BD=EF=BF=BD=EF=BF=BDb=EF=BF=BDX=EF=BF=BD=EF=BF=BD=C7=A7v=EF=BF=BD^=EF= =BF=BD)=DE=BA{.n=EF=BF=BD+=EF=BF=BD=EF=BF=BD=EF=BF=BDz=EF=BF=BD]z=EF=BF= =BD{ay=EF=BF=BD=1D=CA=87=DA=99=EF=BF=BD,j=07=EF=BF=BD=EF=BF=BDf=EF=BF=BD= =EF=BF=BD=EF=BF=BDh=EF=BF=BD=EF=BF=BD=EF=BF=BDz=EF=BF=BD=1E=EF=BF=BDw=EF= =BF=BD=EF=BF=BD=EF=BF=BD=0C=EF=BF=BD=EF=BF=BD=EF=BF=BDj:+v=EF=BF=BD=EF=BF= =BD=EF=BF=BDw=EF=BF=BDj=EF=BF=BDm=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=07= =EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BDzZ+=EF=BF=BD=EF=BF=BD=DD=A2j"=EF=BF= =BD=EF=BF=BD!tml=3D And it is not immediately obvious that this is the bottleneck - from=20 what I can see the 'sync' call being used (sync_file_range) is extremel= y=20 fast and is *not* the major slowdown effect... Regards Mark -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html