From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vladimir Bashkirtsev Subject: Re: Increasing number of PGs Date: Tue, 31 Jul 2012 03:15:40 +0930 Message-ID: <5016C844.7010106@bashkirtsev.com> References: <5013B7E7.3020407@bashkirtsev.com> <5016B34A.8090902@inktank.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]:55169 "EHLO mail.logics.net.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754167Ab2G3Rpz (ORCPT ); Mon, 30 Jul 2012 13:45:55 -0400 In-Reply-To: <5016B34A.8090902@inktank.com> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Josh Durgin Cc: ceph-devel@vger.kernel.org On 31/07/12 01:46, Josh Durgin wrote: > >> So here two questions: >> >> 1. Should I increase number of PGs in rbd pool or better leave it where >> it is? > > It would be better to increase it from a data balancing point of view, > but it's not clear that it would help performance. I would care about data balancing first - as I said it is currently skewed a bit. Performance wise perhaps it will take a bit more CPU/memory to process but not to the extent where it will affect performance. > >> 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? > > Right now the number of pgs in a pool can't be increased. This should > be possible in a couple months. If you can stop I/O to the current pool, > you can create a new one with more pgs, copy all the data to it, delete > the original and rename the new one. Then I am stuck with current number of PGs: pool is in heavy use and there virtually no chance to increase PGs number offline. Will wait for a version which will make it possible.