From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bill Davidsen Subject: Re: write barriers on raid0 and raid10 Date: Wed, 16 Jun 2010 11:37:52 -0400 Message-ID: <4C18EFD0.1030707@tmr.com> References: <4C0E8A88.8010906@cdf.toronto.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4C0E8A88.8010906@cdf.toronto.edu> Sender: linux-raid-owner@vger.kernel.org To: Iordan Iordanov Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids Iordan Iordanov wrote: > Hi, > > We are designing a rather involved file server with an ext3 formatted > stripe (raid0) sitting on top of raid10 devices. Each raid10 device > sits on top of 3 iscsi targets, and has layout n3 (so it is > effectively a 3 way mirror). We chose raid10 over raid1 due to an > apparent read performance benefit of raid10. > > We are trying to decide whether to upgrade to a kernel newer than > 2.6.34, where write barriers are ostensibly supported by all possible > raid types, because we are worried about ext3 corruption with no write > barrier support. > > However, we are also worried about whether write barriers really "make > sense" in a multi-disk environment and are wondering whether they will > actually make a difference in our setup. For argument's sake, let's > assume that our drives honor write cache flushes. > > Can somebody shed some light on how write barriers are implemented in > raid0 and raid10? Also, any critical comments on the validity of our > setup and/or assumptions is also welcome. > I'm sorry not to see an answer here, I'm interested as well. -- Bill Davidsen "We can't solve today's problems by using the same thinking we used in creating them." - Einstein