From mboxrd@z Thu Jan 1 00:00:00 1970 From: Josh Durgin Subject: Re: difference between qemu cache settings and ceph.conf rbd cache settings? Date: Mon, 18 Jun 2012 23:42:54 -0700 Message-ID: <4FE01F6E.50200@inktank.com> References: <4FE01E35.1080002@profihost.ag> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-ob0-f174.google.com ([209.85.214.174]:37540 "EHLO mail-ob0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751919Ab2FSGm4 (ORCPT ); Tue, 19 Jun 2012 02:42:56 -0400 Received: by obbtb18 with SMTP id tb18so9611931obb.19 for ; Mon, 18 Jun 2012 23:42:56 -0700 (PDT) In-Reply-To: <4FE01E35.1080002@profihost.ag> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Stefan Priebe - Profihost AG Cc: "ceph-devel@vger.kernel.org" On 06/18/2012 11:37 PM, Stefan Priebe - Profihost AG wrote: > Hello list, > > i've now patched my qemu to include the qemu cache settings for rbd. > > Now i can change my drive caching mode. But there are also these > settings for global section in ceph.conf. > > rbd_cache = true > rbd_cache_size = 33554432 > rbd_cache_max_age = 2.0 > > How do they influence or replace each other? > > thanks > Stefan In qemu, the cache settings map to: writeback: rbd_cache = true writethrough: rbd_cache = true rbd_cache_max_dirty = 0 none: rbd_cache = false qemu's settings are overridden by any custom settings you have in a config file or on the qemu command line. Josh