From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?ISO-8859-15?Q?Luk=E1=A8_Czerner?= Subject: Re: [PATCH 37/37] ext5: define new subtype to add features and reduce testing complexity Date: Tue, 6 May 2014 17:30:23 +0200 (CEST) Message-ID: References: <20140501231222.31890.82860.stgit@birch.djwong.org> <20140501231629.31890.34812.stgit@birch.djwong.org> <20140506013317.GO8434@birch.djwong.org> <20140506152129.GA31730@thunk.org> Mime-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="8323328-45909237-1399390226=:2255" Cc: "Darrick J. Wong" , linux-ext4@vger.kernel.org To: "Theodore Ts'o" Return-path: Received: from mx1.redhat.com ([209.132.183.28]:53624 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753270AbaEFQEf (ORCPT ); Tue, 6 May 2014 12:04:35 -0400 In-Reply-To: <20140506152129.GA31730@thunk.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --8323328-45909237-1399390226=:2255 Content-Type: TEXT/PLAIN; charset=utf-8 Content-Transfer-Encoding: 8BIT On Tue, 6 May 2014, Theodore Ts'o wrote: > Date: Tue, 6 May 2014 11:21:29 -0400 > From: Theodore Ts'o > To: Lukáš Czerner > Cc: Darrick J. Wong , linux-ext4@vger.kernel.org > Subject: Re: [PATCH 37/37] ext5: define new subtype to add features and reduce > testing complexity > > On Tue, May 06, 2014 at 02:50:39PM +0200, Lukáš Czerner wrote: > > meta_bg - Just makes group descriptors to be spread across the file > > system. It has been around for some time and I am not sure > > why this is not a default already. It should also increase > > the limit of the file system size but I am not sure whether > > this is still true with flex_bg ? > > meta_bg signiicantly slows down mount operations (and in general, any > operation where we need to read in the block group descriptors --- > i.e., dumpe2fs, e2fsck, etc.) > > The strategy for meta_bg is that it's something that we enable as we > need it, as part of an online or off-line resize. That way, we keep > the block groups contiguous for as long as possible. Once the resize > inode has been exhausted (which _will_ happen when the file system > size grows beyond 16T), the resize operation will turn off the > resize_inode feature and then enable the meta_bg feature. > > And this is all working today, with the latest kernel and e2fsprogs; > so there's no reason to enable meta_bg as part of mke2fs operation, > and a good reason not to enable it by default, but to let resize2fs > turn it on when it makes sense to do so. > > - Ted Perfect, thanks for explanation. I was not very sure about meta_bg myself. Thanks! -Lukas --8323328-45909237-1399390226=:2255--