From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wido den Hollander Subject: Re: Finding out via librados if a cluster is near full Date: Wed, 29 May 2013 10:24:18 +0200 Message-ID: <51A5BB32.3040806@42on.com> References: <51A5B8EE.5070801@42on.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from websrv.42on.com ([31.25.102.167]:53985 "EHLO websrv.42on.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964992Ab3E2IYT (ORCPT ); Wed, 29 May 2013 04:24:19 -0400 Received: from [IPv6:2a00:f10:113:0:e9:af4b:b4bc:3103] (unknown [IPv6:2a00:f10:113:0:e9:af4b:b4bc:3103]) by websrv.42on.com (Postfix) with ESMTPSA id 98419C181C for ; Wed, 29 May 2013 10:24:18 +0200 (CEST) In-Reply-To: <51A5B8EE.5070801@42on.com> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: "ceph-devel@vger.kernel.org" On 05/29/2013 10:14 AM, Wido den Hollander wrote: > Hi, > > Is there a way to find out if a cluster is near full via librados? > Yes, there is. (Thanks tnt on IRC!) There is ofcourse rados_cluster_stat which will give you: struct rados_cluster_stat_t { uint64_t kb, kb_used, kb_avail; uint64_t num_objects; }; One thing here is however that you don't know to what the (near)full ratio has been set to. So you have to do your own guessing. > The reason I'm asking is that I'm working on a deployment of the RADOS > Gateway and one of the potential problems I see is that the RADOS > Gateway can keep writing and filling up the whole cluster. > So, with the cluster stat information we could implement: rgw_refuse_write_above_ratio DOUBLE 0.90 > It's obvious that it's the admin's responsibility to make sure that > doesn't happen, but what I'd like to do is make the RADOS Gateway deny > PUT requests when the cluster is near full. > > That way normal meta data operations (thus writes) can continue, but new > objects won't be accepted until the cluster has enough space available. > > This might also be useful for librbd. Refuse the creation of new RBD > images so that existing images can continue operating. > -- Wido den Hollander 42on B.V. Phone: +31 (0)20 700 9902 Skype: contact42on