From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Mason Subject: Re: Btrfs balance Date: Thu, 20 Jan 2011 16:31:20 -0500 Message-ID: <1295558587-sup-5042@think> References: <4D38338B.3090903@gmail.com> Content-Type: text/plain; charset=UTF-8 Cc: linux-btrfs To: Andreas Philipp Return-path: In-reply-to: <4D38338B.3090903@gmail.com> List-ID: Excerpts from Andreas Philipp's message of 2011-01-20 08:07:23 -0500: > > Hi, > > Maybe it is a very stupid question but I want to ask it anyway. In > general, 'btrfs filesystem balance' takes very long to finish and > produces lots of IO. So what are the classical usage scenarios, when > it is (really) worth doing a balance? The idea behind the balance is to spread the used space across all your drives evenly. So you would usually run it after adding a new drive. It's also useful if your disk has a lot of space allocated to either data or metadata and you want to return to a more reasonable default. Josef has a patch to do this more dynamically that we're fixing up (hopefully for 2.6.38-rc2). In general, it isn't something that you want to do very often. -chris