From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Kampe Subject: Re: Newbie questions Date: Sat, 06 Oct 2012 17:34:53 -0700 Message-ID: <5070CE2D.7060008@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-pa0-f46.google.com ([209.85.220.46]:58439 "EHLO mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751334Ab2JGAew (ORCPT ); Sat, 6 Oct 2012 20:34:52 -0400 Received: by mail-pa0-f46.google.com with SMTP id hz1so2939683pad.19 for ; Sat, 06 Oct 2012 17:34:52 -0700 (PDT) In-Reply-To: Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Adam Nielsen Cc: ceph-devel@vger.kernel.org In your original question, I assumed you were talking about the partitioning of a single cluster. Now you are talking about Geographic Disaster Recovery: the replication of data across multiple (relatively) independent clusters. This is not yet supported, but it is most definitely on the road-map. On 10/6/2012 5:08 PM, Adam Nielsen wrote: >> The problem you are describing is called split-brain. Ceph has an odd >> number of monitors and quorum is required before objects can be served. >> The partition with the smaller number of monitors will wait harmlessly >> until connectivity is reestablished . > > Ah right, that makes sense. Is this set in stone or can it be > configured? I'm just thinking that in this scenario it could be > beneficial to allow read-only access from the partition with the smaller > number of monitors, if there are also clients that can only see those > hosts. (For example, a business with two sites, and the link between > them goes down, so client PCs can only see their site-local servers.)