From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefan Priebe - Profihost AG Subject: Re: OSD Hardware questions Date: Thu, 28 Jun 2012 15:21:18 +0200 Message-ID: <4FEC5A4E.1090209@profihost.ag> References: <4FEB04CC.4050008@profihost.ag> <4FEB10DA.7010206@inktank.com> <4FEB2310.9080801@profihost.ag> <4FEB26A7.4070507@profihost.ag> <4FEB2E07.6010402@inktank.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail.profihost.ag ([85.158.179.208]:50917 "EHLO mail.profihost.ag" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755773Ab2F1NVX (ORCPT ); Thu, 28 Jun 2012 09:21:23 -0400 In-Reply-To: <4FEB2E07.6010402@inktank.com> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Mark Nelson Cc: Gregory Farnum , "ceph-devel@vger.kernel.org" Am 27.06.2012 18:00, schrieb Mark Nelson: > On 06/27/2012 10:28 AM, Stefan Priebe wrote: >>> Well, as we said, 1GHz/OSD was a WAG (wild-ass guess), but 3.6GHz+/OSD >>> is farther outside of that range than I would have expected. It might >>> just be a consequence of using SSDs, since they can sustain so much more >>> throughput. >> >> Sure it was just so much away from 1Ghz that i wanted to ask. >> >>> What is the cluster doing when you see those CPU usage numbers? >> random write I/O from one KVM. 14k I/Ops with random 4k writes. >> >> Stefan > > I think I was seeing about 80-85% CPU utilization with 5 SSD OSDs on our > 6-core AMD nodes, but I was just doing sequential writes with rados bench. While doing sequential writes i see pretty low CPU usage. Random writes is the problem. Stefan