From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Kirkwood Subject: Osd placement rule questions Date: Thu, 05 Jul 2012 15:45:22 +1200 Message-ID: <4FF50DD2.6030507@catalyst.net.nz> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from bertrand.catalyst.net.nz ([202.78.240.40]:46854 "EHLO mail.catalyst.net.nz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751208Ab2GEDve (ORCPT ); Wed, 4 Jul 2012 23:51:34 -0400 Received: from localhost (localhost [127.0.0.1]) by mail.catalyst.net.nz (Postfix) with ESMTP id 40BAE31FF5 for ; Thu, 5 Jul 2012 15:45:23 +1200 (NZST) Received: from mail.catalyst.net.nz ([127.0.0.1]) by localhost (bertrand.catalyst.net.nz [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id LuwAiAOVfUh3 for ; Thu, 5 Jul 2012 15:45:22 +1200 (NZST) Received: from [IPv6:2404:130:0:1000:982:3f18:550f:4cb] (unknown [IPv6:2404:130:0:1000:982:3f18:550f:4cb]) (Authenticated sender: mark.kirkwood) by mail.catalyst.net.nz (Postfix) with ESMTPSA id A67D631D04 for ; Thu, 5 Jul 2012 15:45:22 +1200 (NZST) Sender: ceph-devel-owner@vger.kernel.org List-ID: To: ceph-devel@vger.kernel.org Hi, I am experimenting with ceph (rbd only for now), and have a few questions about what is possible via placement rules. For example I am looking at a setup with a local datacenter (datacenter0) and a remote one (datacenter1). I'm using a placement rule: rule rbd { ruleset 2 type replicated min_size 1 max_size 10 step take datacenter0 step chooseleaf firstn -1 type host step emit step take datacenter1 step chooseleaf firstn 1 type host step emit } and I have the rdb pool set to size 3. So I *think* I am saying I want 2 replicas in datacenter0 and one in datacenter1 [1]. The questions I have are: 1/ I would like to be able to have a way to say something like: Make 2 copies at datacenter0, 1 at datacenter1 - wait for the ones at datacenter0 to be written but not the ones at datacenter1 (so asynchronous for the latter). Is this possible, or planned? 2/ Also I would like to be able to say make my number of copies 3, but if I lose datacenter0 (where 2 copies are), don't try to have 3 copies at datacenter1 (so run degraded in that case). Is that possible? Cheers Mark [1] Might make more sense to have 2 copies at each, but I'm just trying to see how this placement business works at this point...