From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joao Eduardo Luis Subject: Re: Very intensive I/O under mon process Date: Wed, 02 Jan 2013 16:00:23 +0000 Message-ID: <50E45997.9060205@inktank.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-la0-f54.google.com ([209.85.215.54]:64906 "EHLO mail-la0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752788Ab3ABQAu (ORCPT ); Wed, 2 Jan 2013 11:00:50 -0500 Received: by mail-la0-f54.google.com with SMTP id fp12so6338747lab.13 for ; Wed, 02 Jan 2013 08:00:48 -0800 (PST) In-Reply-To: Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Andrey Korolyov Cc: ceph-devel On 01/02/2013 03:40 PM, Andrey Korolyov wrote: > I have just observed that ceph-mon process, at least bobtail one, has > an extremely high density of writes - times above _overall_ cluster > amount of writes, measured by qemu driver(and they are very close to > be fair). For example, test cluster of 32 osds have 7.5 MByte/s of > writes on each mon node having overall amount about 1.5 Mbyte/s and > dev- with only three osds has values is about 1Mbyte/s with > accumulated real write bandwidth of tens of kilobytes per second. > > I`m afraid if this is normal, I may hit a limit of spinning storage > increasing test cluster, say, twenty times up of number of osd and > related ``idle'' write bandwidth. High debugging levels (specially 'debug ms', 'debug mon' or 'debug paxos') should significantly increase IO on the monitors. Might that be the case? -Joao