From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefan Priebe - Profihost AG Subject: Re: Heavy speed difference between rbd and custom pool Date: Tue, 19 Jun 2012 15:14:18 +0200 Message-ID: <4FE07B2A.7080209@profihost.ag> References: <4FE01CE7.8000204@profihost.ag> <4FE0782A.1060104@inktank.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail.profihost.ag ([85.158.179.208]:35314 "EHLO mail.profihost.ag" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752565Ab2FSNOW (ORCPT ); Tue, 19 Jun 2012 09:14:22 -0400 In-Reply-To: <4FE0782A.1060104@inktank.com> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Mark Nelson Cc: Alexandre DERUMIER , ceph-devel@vger.kernel.org Am 19.06.2012 15:01, schrieb Mark Nelson: > On 06/19/2012 01:32 AM, Stefan Priebe - Profihost AG wrote: >> Am 19.06.2012 06:41, schrieb Alexandre DERUMIER: >>> Hi Stephann >>> recommandations are 30-50 PGS by osd if I remember. >>> >> rbd, data and metadata have 2176 PGs with 12 OSD. This is 181,333333333 >> per OSD?! >> >> Stefan > > That's probably fine, it just means that you will have a better > pseudo-random distribution of OSD combinations (It does have higher > cpu/memory overhead though). Figuring out how many PGs you should have > per OSD depends on a lot of factors including how many OSDs you have, > how many nodes, CPU, memory, etc. I'm guessing ~180 per OSD won't cause > problems. On the other hand, with low OSD counts you could probably have > fewer and be fine too. But this number 2176 of PGs were set while doing mkcephfs - how is it calculated? Stefan