From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <3AB5AFC0.5C4A58C9@dataventures.com> Date: Mon, 19 Mar 2001 00:05:36 -0700 From: Donald Thompson MIME-Version: 1.0 Subject: Re: [linux-lvm] Apparent performance degradation for each PV with striping References: <3AB59501.FF6ED9F3@dataventures.com> <15029.41256.426234.309500@nv.192.168.71.6> Content-Transfer-Encoding: 7bit Sender: linux-lvm-admin@sistina.com Errors-To: linux-lvm-admin@sistina.com Reply-To: linux-lvm@sistina.com List-Help: List-Post: List-Subscribe: , List-Unsubscribe: , List-Archive: List-Id: Content-Type: text/plain; charset="us-ascii" To: linux-lvm@sistina.com Actually, I've learned a lot from Eric's comments. After looking into hdparm and a couple other things, it looks like the kernel settings as well as hdparm settings are set to about the worst possible (ie. safest) I could have. Probably most importantly, they aren't using DMA, and I'll need to recompile the kernel to get it to do so. I actually was thinking seriously about getting a 3ware card when I started this machine, but I wussed out and just went with the two onboard IDE interfaces. Its definately a cheaper option than replacing or adding SCSI drives to the system. -Don lvm@winux.com wrote: > Donald Thompson writes: > > I notice during the dd operation that my system CPU state is 90% or > > more. So I think I just answered my own question, I'm CPU bound. > > Moving on, is there any known ways to improve my performance off > > each PV with this type of hardware setup? > > ... > > Should I expect that I won't see the performance drop on individual PV's > > with striping on SCSI drives? I originally setup this system with no > > intentions of it being a high performance file server, until a few > > people I work with decided they wanted to use it for a database machine. > > So I'm not afraid to spend a couple grand to get some faster disks in it > > if thats the only thing > > thats gonna help me. > > Hi Donald, > > I think what you're seeing is to be expected from vanilla IDE. > Not only is it not Linux LVM's fault but Linux LVM can't fix it. > IDE controllers are not able to do the things more sophisicated > controllers and host adapters do to increase performance in a > multi-spindle environment. Fortunately, there is a solution that's > fast, cheap, and reliable. > > I suggest that, rather than replacing the drives with > expensive SCSI drives and an expensive SCSI host adapter, > you buy an Escalade Switch from http://www.3ware.com/ and > use your existing drives. > > The Escalade is a hybrid controller of sorts. It presents itself as a > SCSI host adapter to the host's PCI bus and as multiple (up to 8) > independent IDE controllers to the IDE drives. It's essentially a > cross-bar switch that lets multiple IDE drives act independently of > one another. They use some clever controller software to get a BETTER > than 2x boost in read-performance when you mirror drives. > > It has the additional advantage of providing RAID for the attached drives. > It supports RAID 0, 1, 10, and 5, so you get all those benefits > without imposing ANY additional CPU load. The controller is actually > quite a gem and is very reasonably priced. I've been using them on > all of my systems where performance and/or reliability are critical. > > The Escalade driver is supported in the standard 2.2.x and 2.4.x Linux kernels. > > In short, let 3ware's hardware handle the striping/RAID and use Linux LVM > to manage the volume. It's a powerful combination. > > Larry > > DISCLAIMER: These statements reflect my personal opinions... bla bla bla. > I don't have any affiliation with 3ware or anyone else in this business. > > CLAIMER: 3ware makes good stuff that works very well. > It solved my problems and it could solve yours. > _______________________________________________ > linux-lvm mailing list > linux-lvm@sistina.com > http://lists.sistina.com/mailman/listinfo/linux-lvm