From mboxrd@z Thu Jan 1 00:00:00 1970 From: Illtud Daniel Subject: Re: about the speed Date: Wed, 02 Apr 2003 10:58:29 +0100 Sender: linux-raid-owner@vger.kernel.org Message-ID: <3E8AB445.A76ED9D6@llgc.org.uk> References: <3E87FC9D.5010605@bnap.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: To: raid-list List-Id: linux-raid.ids =46arkas Levente wrote: > I'm just read > http://www.hpl.hp.com/techreports/2002/HPL-2002-352.pdf > may be it's worth to read. an intersting thing about performance (XP, > their user-space raid and than comes kernel raid). Any comments from md developers? This is from the abstract: The paper contains preliminary results from an investigation comparing Linux and WindowsXP disk I/O using kernel-based software RAID on identical hardware. WindowsXP performance is shown to be substantially superior to Linux performance, for reasons not currently understood. And the meat of the report: 5.5. Direct comparison Of crucial interest is the direct comparison between WindowsXP, the kernel-based Linux software RAID implementation, and the userlevel software RAID implementation. From Figure 8 it can be seen that csraid generally outperforms the kernel-based RAID driver, and its performance is far more stable, particularly for large requests. Also, the WindowsXP RAID driver is astonishingly good, even compared to JBOD, with JBOD=92s performing better for request sizes smaller than 4MB and WindowsXP performing better at the larger sizes. csraid=92s performance is generally less than WindowsXP, but overall the loss is not catastrophic, and is likely sufficient for the most purposes. =46igure 8 shows that XP's RAID can be 60+% faster than md at writing, and up to 100% faster at reading (at request size 7MB, which is rather a blip). Any inital thoughts on this report? Has the performance changed substantially since? The distro was Mandrake 8.2, the kernel 2.4.18-6mdk. Any comments on the methodology or conclusions? --=20 Illtud Daniel illtud.daniel@llgc.org.uk Uwch Ddadansoddwr Systemau Senior Systems Analyst Llyfrgell Genedlaethol Cymru National Library of Wales Yn siarad drosof fy hun, nid LlGC - Speaking personally, not for NLW - To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html