From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vladimir Bashkirtsev Subject: Increasing number of PGs Date: Sat, 28 Jul 2012 19:23:11 +0930 Message-ID: <5013B687.6020103@bashkirtsev.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail.logics.net.au ([150.101.56.178]:37843 "EHLO mail.logics.net.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751329Ab2G1Jzn (ORCPT ); Sat, 28 Jul 2012 05:55:43 -0400 Received: from x.logics.net.au (gw.logics.net.au [150.101.235.251] (may be forged)) (authenticated bits=0) by mail.logics.net.au (8.14.5/8.14.1) with ESMTP id q6S9rBPD017770 (version=TLSv1/SSLv3 cipher=DHE-RSA-CAMELLIA256-SHA bits=256 verify=NO) for ; Sat, 28 Jul 2012 19:23:12 +0930 Sender: ceph-devel-owner@vger.kernel.org List-ID: To: ceph-devel@vger.kernel.org Hello, I am working on optimization of ceph performance: CPU load vs OSD data load. Right now I have 576 PGs in total. Three pools: metadata, data, rbd. Each pool has 192 PGs. data is not used heavily, rbd is in heavy use. In total 6 OSDs in cluster. I have read recommendation about 100 PGs per OSD. Roughly I do have 100 PGs per OSD. But now it seems that PGs in data pool are mostly empty while PGs in rbd pool are quite busy. Would it make sense to increase number of PGs to be 100 per rbd pool per OSD? Technically it should take some memory and CPU but because other two pools are virtually stand still it should not make big difference while improving data placement on OSDs (which is currently somewhat skewed). So here two questions: 1. Should I increase number of PGs in rbd pool or better leave it where it is? 2. Wiki says that increase in PGs is not tested and only should be attempted on empty pool. Date on Wiki is quite old. Is this still an issue? Is it safe to increase PGs number on 0.49 on pool in use? Regards, Vladimir