From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 2 May 2002 15:58:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 2 May 2002 15:58:34 -0400 Received: from unthought.net ([212.97.129.24]:1685 "HELO mail.unthought.net") by vger.kernel.org with SMTP id ; Thu, 2 May 2002 15:58:34 -0400 Date: Thu, 2 May 2002 21:58:33 +0200 From: =?iso-8859-1?Q?Jakob_=D8stergaard?= To: Martin Dalecki Cc: Pavel Machek , Roy Sigurd Karlsbakk , linux-kernel@vger.kernel.org Subject: Re: IDE hotplug support? Message-ID: <20020502215833.V31556@unthought.net> Mail-Followup-To: =?iso-8859-1?Q?Jakob_=D8stergaard?= , Martin Dalecki , Pavel Machek , Roy Sigurd Karlsbakk , linux-kernel@vger.kernel.org In-Reply-To: <20020426152943.A413@toy.ucw.cz> <3CD18318.7060407@evision-ventures.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit User-Agent: Mutt/1.2i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 02, 2002 at 08:19:04PM +0200, Martin Dalecki wrote: ... > 15 drives == 16 interfaces == 8 channels == 4 controllers > with primary and secondary channel. Usually using both master and slave on an IDE channel spells disaster performance wise, and I would be surprised if the hotplug stuff worked with this as well... > > He will have groups of about 4 drives on each channel wich > serialize each other due to excessive IRQ line sharing and > master slave issues. Use 8 controllers for the 15 (16) drives. > > 8 x 130MBy/s >>>> PCI bus throughput... I would rather recommend > a classical RAID controller card for this kind of > setup. Because RAID controllers do not use the PCI bus ??? ;) The bus-overhead on RAID-5 is not too bad unless you specifically construct a workload to make it so (writes-only, scattered so that the kernel cannot cache stripes to avoid read-in for parity calculation). Sure, the PCI bus will be a bottleneck, and PCI overhead alone will decrease the real-world performance to somewhere below the theoretical PCI bandwidth limitations, but don't let this blind you - 100 MB/sec sustained transfers can still be "good enough" for many people. By the way, has anyone tried such larger multi-controller setups, and tested the bandwidth in configurations with multiple PCI busses on the board, versus a single PCI bus ? -- ................................................................ : jakob@unthought.net : And I see the elder races, : :.........................: putrid forms of man : : Jakob Østergaard : See him rise and claim the earth, : : OZ9ABN : his downfall is at hand. : :.........................:............{Konkhra}...............: