From mboxrd@z Thu Jan 1 00:00:00 1970 From: mark delfman Subject: Re: xfs > md 50% write performance drop on .30+ kernel? Date: Tue, 13 Oct 2009 16:13:46 +0100 Message-ID: <66781b10910130813u7f9ca010t7cd05214be729fff@mail.gmail.com> References: <66781b10910120958k4afb637ejba79e4c23900c4da@mail.gmail.com> <20091013013352.GA24869@infradead.org> <66781b10910130406s4119985fg5db7679a2e9fd4f2@mail.gmail.com> <70ed7c3e0910130409r1e1350b6yabfdc3d4f5c51edf@mail.gmail.com> <66781b10910130412x309d9de2l574ba12a9ed4100a@mail.gmail.com> <70ed7c3e0910130415k4da86d18kd92dce5217b8600d@mail.gmail.com> <4AD48EFA.50303@shiftmail.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Return-path: In-Reply-To: <4AD48EFA.50303@shiftmail.org> Sender: linux-raid-owner@vger.kernel.org To: Asdo Cc: LinuxRaid List-Id: linux-raid.ids We dont use 10 ports, we use 8 ports > 36 port expander. The 8 ports act as a single wide port. We are hitting a performance limit of circa 1.6 - 1.9GBsec regardless of number of drives, so it max's at around 8 / 9 drives (with 15K). RAID6 around 900MBsec i recall. We expect more with emerging expanders. We were hoping to use DM MPIO to increase performance using multiple cards and paths, but MPIO at best matches performance of a single card, most likely pulls it down.... but this is a different topic i guess. XFS in the past has often increased performance - not allows on simple sequential writes, but FS's are a lot better at intelligently caching data... so I am very keen to help in whatever way i can to resolve the FS > MD performance problem. Thanks again.... Mark On Tue, Oct 13, 2009 at 3:30 PM, Asdo wrote: > >> On Tue, Oct 13, 2009 at 2:12 PM, mark delfman >> wrote: >> >>> >>> We upgrading mainly because of support for the emerging LSI SAS2 cards >>> (which we are beta testing now) >>> > > What is this LSI SAS2 card you have with 10+ ports? The only 10+ ports LSI > card I see is the 84016E and it is a SAS1. > > You say the driver for such card is included in the vanilla kernel at > 2.6.30? That would be very nice... I grepped the 2.6.31 kernel source for > LSI cards but I can't find device strings such as 84016E ... > > Thank you >