From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262344AbTLPVLD (ORCPT ); Tue, 16 Dec 2003 16:11:03 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262598AbTLPVLC (ORCPT ); Tue, 16 Dec 2003 16:11:02 -0500 Received: from astound-64-85-224-253.ca.astound.net ([64.85.224.253]:13837 "EHLO master.linux-ide.org") by vger.kernel.org with ESMTP id S262344AbTLPVK6 (ORCPT ); Tue, 16 Dec 2003 16:10:58 -0500 Date: Tue, 16 Dec 2003 13:04:12 -0800 (PST) From: Andre Hedrick To: Helge Hafting cc: jw schultz , Linux Kernel Mailing List Subject: Re: raid0 slower than devices it is assembled of? In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Size is MB, BlkSz is Bytes, Read, Write, and Seeks are MB/secd . -T File Block Num Seq Read Rand Read Seq Write Rand Write Dir Size Size Thr Rate (CPU%) Rate (CPU%) Rate (CPU%) Rate (CPU%) ------- ------ ------- --- ----------- ----------- ----------- ----------- . 2018 4096 1 244.7 53.6% 8.847 2.26% 88.04 41.7% 5.594 7.16% . 2018 4096 2 281.6 65.6% 11.04 3.53% 89.86 69.5% 6.645 9.78% . 2018 4096 4 235.6 64.3% 13.91 4.45% 88.26 96.2% 7.647 12.7% . 2018 4096 8 231.2 68.0% 15.91 5.34% 85.59 105.% 7.557 10.3% Two channel, Six drives, three per channel. U320 with 15K U160 drives in a soft Raid 0. Andre Hedrick LAD Storage Consulting Group On Tue, 16 Dec 2003, Andre Hedrick wrote: > > Helge, > > Reads you may gain on writes only if all devices are on single ended mode. > Both pATA and pSCSI suck wind in writes, pSCSI should smoke pATA on reads. > It is all a matter of the physical protocol on the wire. > > Only in SATA/SAS will you even reach close to ideal world. > > Cheers, > > Andre Hedrick > LAD Storage Consulting Group > > On Tue, 16 Dec 2003, Helge Hafting wrote: > > > jw schultz wrote: > > > > > No Linux [R]AID improves sequential performance. How would > > > reading 65KB from two disks in alternation be faster than > > > reading continuously from one disk? > > > > > Raid-0 is ideally N times faster than a single disk, when > > you have N disks. Because you can read continuously from N > > disks instead of from 1, thereby N-doubling the bandwith. > > > > Wether the current drivers manages that is of course another story. > > > > Helge Hafting > > > > > > - > > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > Please read the FAQ at http://www.tux.org/lkml/ > > > > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >