From: Andreas Dilger Subject: Re: flex_bg with tune2fs posible? Date: Sat, 9 Apr 2011 17:01:53 -0600 Message-ID: <613129CE-D1B7-46BB-8C0F-B94BB7E2011E@dilger.ca> References: <20110409215017.GA17008@vip.manty.net> Mime-Version: 1.0 (iPhone Mail 8F190) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8BIT Cc: "linux-ext4@vger.kernel.org" To: Santiago Garcia Mantinan Return-path: Received: from shawmail.shawcable.com ([64.59.128.220]:30313 "EHLO mail.shawcable.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755697Ab1DIXBt convert rfc822-to-8bit (ORCPT ); Sat, 9 Apr 2011 19:01:49 -0400 In-Reply-To: <20110409215017.GA17008@vip.manty.net> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 2011-04-09, at 3:50 PM, Santiago Garcia Mantinan wrote: > I had converted an ext3 filesystem to ext4 long ago but comparing it's > features with the ones found on a newly formatted ext4 filesystem I found > that I had these features missing: > flex_bg huge_file dir_nlink extra_isize > Current doc at ext4.wiki.kernel.org says: "There are additional ext4 > features, such as flex_bg and > 16TB filesystem support that can only > be enabled at format time via mke2fs." > > I did activate all these 4 without any problem (2.6.38 with 1.41.12 > e2fsprogs) is the doc old and doesn't reflect that this is now possible? > > Or have I done something I'll regret? Technically, flex_bg can be activated after the filesystem is formatted, but it doesn't actually provide the benefit as if enabled at format time. The dir_nlink and huge_file features can safely be enabled on an existing filesystem, allowing > 64000 subdirs and > 2 TB files, respectively. The extra_isize feature will not itself do anything if the filesystem wasn't formatted with large inodes (>128 bytes), though it is possible this was done even for ext3, depending on the version of e2fsprogs used. > So far the filesystem seems ok (e2fsck doesn't detect any problems) and > files seem ok as well.