From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ric Wheeler Subject: Re: [dm-devel] Barriers still not passing on simple dm devices... Date: Sun, 05 Apr 2009 18:24:13 -0700 Message-ID: <49D959BD.7060002@redhat.com> References: <20090324150517.GX27476@kernel.dk> <20090326084205.GG27476@kernel.dk> <20090331104933.GJ5178@kernel.dk> <20090403081131.GP5178@kernel.dk> <49D77AC3.3020207@redhat.com> <20090405012839.GF7553@mit.edu> <49D89C06.1060700@gmail.com> <75b66ecd0904051814n353bb69bp76a38e36cac4d3fe@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <75b66ecd0904051814n353bb69bp76a38e36cac4d3fe@mail.gmail.com> Sender: linux-kernel-owner@vger.kernel.org To: Lee Revell Cc: Ric Wheeler , Theodore Tso , Jens Axboe , Mikulas Patocka , device-mapper development , Linux Kernel Mailing List , ak@linux.intel.com, "MASON, CHRISTOPHER" List-Id: dm-devel.ids On 04/05/2009 06:14 PM, Lee Revell wrote: > On Sun, Apr 5, 2009 at 7:54 AM, Ric Wheeler wrote: >> One thing to point out here is that there are a lot of "servers" in high end >> data centers that do not have UPS backup. Those racks full of 1U and 2U >> boxes that are used to make "grids", "clouds" and so on often are built with >> as much gear as you can stuff in a rack - no batteries or UPS to be seen, so >> they are really quite similar to the normal desktop or home systems that we >> normally run at home :-) > > These days even bargain basement data centers provide UPS functionality for > you, via generator backup and A/B power. > > Lee In my experience, you will see multiple customers with and without UPS backup. I have certainly dealt personally with many data centers that lost power without them & see array vendors that continue to build in their own batteries... ric