From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steve Cousins Subject: Re: MD write performance issue - found Catalyst patches Date: Wed, 04 Nov 2009 14:05:45 -0500 Message-ID: <4AF1D089.5080901@maine.edu> References: <66781b10910180300j2006a4b7q21444bb27dd9434e@mail.gmail.com> <19177.14609.138378.581065@notabene.brown> <4AE94D95.4060303@shiftmail.org> <66781b10910310351x7bb721c4mfba765fe9789cd7b@mail.gmail.com> <19183.47226.529417.743975@notabene.brown> <66781b10911030411y5bb32610lec72966f7cc09df@mail.gmail.com> <66781b10911040915t11a7f0c2td6a9ed5672935efb@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <66781b10911040915t11a7f0c2td6a9ed5672935efb@mail.gmail.com> Sender: linux-raid-owner@vger.kernel.org To: mark delfman Cc: linux-raid List-Id: linux-raid.ids mark delfman wrote: > Some FS comparisons attached in pdf > > not sure what to make of them as yet, but worth posting > I'm not sure either. Two things jump out. 1. Why is raw RAID0 read performance slower than write performance 2. Why is read performance with some file systems at or above raw read performance? For number one, does this indicate that write caching is actually On on the drives? Are all tests truly apples-apples comparisons or were there other factors in there that aren't listed in the charts? I guess these issues might not have a lot to do with your main question but you might want to double-check the tests and numbers. Steve