From: Eric Sandeen Subject: Re: mkfs.ext4: high default -i value undocumented Date: Tue, 03 Mar 2009 18:43:39 -0600 Message-ID: <49ADCEBB.6080904@redhat.com> References: <49ADBB03.9070303@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: linux-ext4@vger.kernel.org, kzak@redhat.com To: Jan Engelhardt Return-path: Received: from mx2.redhat.com ([66.187.237.31]:48295 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751084AbZCDAnp (ORCPT ); Tue, 3 Mar 2009 19:43:45 -0500 In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: Jan Engelhardt wrote: > On Wednesday 2009-03-04 00:19, Eric Sandeen wrote: >>> Creating an ext4 filesystem on a 4 GB image file (to be loop-mounted >>> later) gives me 256K inodes. Choosing -i 4096 instead gives 1M, which >>> would mean the default for -i is 16384. >> That's right, look in /etc/mke2fs.conf: >> >> [defaults] >> base_features = >> sparse_super,filetype,resize_inode,dir_index,ext_attr >> blocksize = 4096 >> inode_size = 256 >> inode_ratio = 16384 > > Interesting - thanks for the hint. > >>> Besides me finding 16384 a >>> little unreasonable (XFS offers 2M inodes by default), >> XFS is a totally different beast, because it dynamically allocates >> inodes. It doesn't really offer *anything* by default. >> >> Which part of a 16384-data-bytes-to-inode-count ratio do you find >> unreasonable? Do you find it unreasonably high, or unreasonably low? > > I think it's a bit too high, causing the amount of usable inodes > to be a bit too low. When we doubled the size of inodes by default, we halved the count. I also have a sneaking suspicion that it may be too low for some scenarios, but probably ok for most. >>> the big >>> point is that the mke2fs manpage (belonging to util-linux, hence Cc) >> not so much: >> $ rpm -qf /usr/share/man/man8/mke2fs.8.gz >> e2fsprogs-1.41.3-2.fc10.x86_64 > > Sorry, I had looked for man8/mkfs.ext2.8.gz. I am not quite sure > what makes some developers deviate(*) from the mkfs.$name/fsck.$name > scheme ;-) $ rpm -qf /usr/share/man/man8/mkfs.ext2.8.gz e2fsprogs-1.41.3-2.fc10.x86_64 :) > (*) e2, reiser(3), dosfs > >>> does not mention this 16384 default. >>> Hope this can be addressed. >> You could send a patch :) > > parent b2ca48f40eb33bd86b8d53d4373e7fce96bced4a (v1.41.4) > commit ca28058c4004ceaa42edeb6ba61bc2aa53d7c03d > Author: Jan Engelhardt > Date: Wed Mar 4 01:36:09 2009 +0100 > > doc: mention default for mke2fs -i thanks :) (up to Ted now) -Eric