From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefan Priebe - Profihost AG Subject: Rados faster than KVM block device? Date: Thu, 28 Jun 2012 15:10:22 +0200 Message-ID: <4FEC57BE.9060703@profihost.ag> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail.profihost.ag ([85.158.179.208]:40342 "EHLO mail.profihost.ag" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755030Ab2F1NK2 (ORCPT ); Thu, 28 Jun 2012 09:10:28 -0400 Sender: ceph-devel-owner@vger.kernel.org List-ID: To: "ceph-devel@vger.kernel.org" Hello list, my cluster is now pretty stable i'm just wondering about the sequential write values. With rados bench command and 16 threads i get totally different values than with KVM and rbd block device. rados -p kvmpool bench 60 write -t 16: pool size 2: Bandwidth (MB/sec): 1137.294 pool size 3: Bandwidth (MB/sec): 846.983 Inside KVM with fio: fio --filename=$DISK --direct=1 --rw=write --bs=4M --size=200G --numjobs=16 --runtime=60 --group_reporting --name=file1: pool size 2: write: io=32984MB, bw=562046KB/s, iops=137 , runt= 60094msec pool size 3: write: io=29124MB, bw=496024KB/s, iops=121 , runt= 60124msec Even when i change the pool size to 3 i get with fio 520MB/s. Any ideas? Is this expected? Greets Stefan