From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefan Priebe - Profihost AG Subject: Re: mon disk access pattern Date: Mon, 18 Jun 2012 08:39:38 +0200 Message-ID: <4FDECD2A.5090607@profihost.ag> References: <4FDACD90.2080807@profihost.ag> <4FDB05A7.3080202@widodh.nl> <4FDB1DCC.6090701@inktank.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail.profihost.ag ([85.158.179.208]:45054 "EHLO mail.profihost.ag" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751308Ab2FRGjk (ORCPT ); Mon, 18 Jun 2012 02:39:40 -0400 In-Reply-To: <4FDB1DCC.6090701@inktank.com> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Mark Nelson Cc: Wido den Hollander , "ceph-devel@vger.kernel.org" Am 15.06.2012 13:34, schrieb Mark Nelson: > On 06/15/2012 04:51 AM, Wido den Hollander wrote: >> Hi, >> >> On 15-06-12 07:52, Stefan Priebe - Profihost AG wrote: >>> Hello list, >>> >>> i read somewhere that the mon has "special" disk access patterns - even >>> though it does not write much data. >> >> "special"? Where did you read that? The monitor has about 1 ~ 2GB of >> storage. >> >> So if your monitor has something like 4GB ~ 8GB of RAM, your kernel >> should cache almost all your monitor data. >> > > I think at some point someone mentioned to me that the mon can cause a > lot of syncs, so running them on the OSDs without syncfs might be > detrimental. For the majority of our internal performance testing I've > kept them off the OSDs just to be sure. My main idea behind that was what type of disk i need for a performant mon system. SATA, SAS, SSD? Raid? Stefan