From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tomasz Chmielewski Subject: Re: Ceph on just two nodes being clients - reasonable? Date: Wed, 19 Jan 2011 13:14:43 +0100 Message-ID: <4D36D5B3.4040601@wpkg.org> References: <4D36BDF9.4030404@wpkg.org> <1295437286.2255.25.camel@wido-desktop> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail.virtall.com ([178.63.195.102]:53738 "EHLO mail.virtall.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753878Ab1ASMOs (ORCPT ); Wed, 19 Jan 2011 07:14:48 -0500 In-Reply-To: <1295437286.2255.25.camel@wido-desktop> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Wido den Hollander Cc: ceph-devel@vger.kernel.org On 19.01.2011 12:41, Wido den Hollander wrote: > Hi Thomas, > > I think the answer is Yes and No on this question, the devs might have > another approach for your situation. > > If you would do this, you would have a MON, MDS and OSD on every server, > in theory that would work. Mounting would be done by connecting to on of > the MON's (doesn't matter which one). > > But Ceph requires, well, advises a odd number of monitors (Source: > http://ceph.newdream.net/wiki/Designing_a_cluster ) > > So you would require a third node which is running your third monitor to > keep track of both nodes. > > My advise, for two nodes, use something like DRBD in Primary<> Primary > and use a cluster filesystem like OCFS2. Currently, I'm running glusterfs in such a scenario (two servers, each being also clients), but I wanted to give ceph a try (glusterfs has some performance issues with lots of small files), also because of its nice features (snapshots, rbd etc.). -- Tomasz Chmielewski http://wpkg.org