From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andy Smith Subject: Re: Can extremely high load cause disks to be kicked? Date: Fri, 1 Jun 2012 19:25:24 +0000 Message-ID: <20120601192524.GH3867@bitfolk.com> References: <20120531083158.GE3867@bitfolk.com> <4FC81B85.8090807@hardwarefreak.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <4FC81B85.8090807@hardwarefreak.com> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Hi Stan, On Thu, May 31, 2012 at 08:31:49PM -0500, Stan Hoeppner wrote: > On 5/31/2012 3:31 AM, Andy Smith wrote: > > Now, is this sort of behaviour expected when under incredible load? > > Or is it indicative of a bug somewhere in kernel, mpt driver, or > > even flaky SAS controller/disks? > > It is expected that people know what RAID is and how it is supposed to > be used. RAID is to be used for protecting data in the event of a disk > failure and secondarily to increase performance. That is not how you > seem to be using RAID. Just to clarify, this was the hypervisor host. The VMs on it don't use RAID themselves as that would indeed be silly. > There are a number of scenarios where md RAID is better than hardware > RAID and vice versa. Yours is a case where hardware RAID is superior, > as no matter the host CPU load, drives won't get kicked offline as a > result, as they're under the control of a dedicated IO processor (same > for SAN RAID). Fair enough, thanks. Cheers, Andy