From: Jan Engelhardt Subject: ext4 offers less blocks than other fs Date: Tue, 15 Nov 2011 20:51:18 +0100 (CET) Message-ID: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII To: linux-ext4@vger.kernel.org Return-path: Received: from seven.medozas.de ([188.40.89.202]:49578 "EHLO seven.medozas.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757327Ab1KOTvT (ORCPT ); Tue, 15 Nov 2011 14:51:19 -0500 Received: from localhost (localhost [127.0.0.1]) by seven.medozas.de (Postfix) with ESMTP id 14EF121A01DF for ; Tue, 15 Nov 2011 20:51:18 +0100 (CET) Sender: linux-ext4-owner@vger.kernel.org List-ID: Hi. In moving away from some ntfs-3g filesystem to ext4 (migration of a Windows-esque fileserver), I see a rather steep metadata use with ext4 such that moving the data was not completely possible. Per df: Filesystem 1K-blocks Used Available Use% Mounted on /dev/dm-5 1953514324 1952543856 970468 100% /mnt/old /dev/mapper/data 1922858888 1922858880 0 100% /mnt/new [attempted a rsync as root] The blockdev size is just minimally different: 20:32 nas:~ # blockdev --getsize64 /dev/dm-5 2000398671872 20:32 nas:~ # blockdev --getsize64 /dev/dm-6 2000396836864 And there is a 29 GB(!) difference between 1953514324 and 1922858888, so my question is: where is all of that going? (e2fsprogs 1.41.14) Filesystem volume name: data Last mounted on: /mnt/new Filesystem UUID: 807fec49-7a8a-3520-a648-be677475377c Filesystem magic number: 0xEF53 Filesystem revision #: 1 (dynamic) Filesystem features: has_journal ext_attr resize_inode dir_index filetype needs_recovery extent flex_bg sparse_super large_file huge_file uninit_bg dir_nlink extra_isize Filesystem flags: signed_directory_hash Default mount options: (none) Filesystem state: clean Errors behavior: Continue Filesystem OS type: Linux Inode count: 122101760 Block count: 488378134 Reserved block count: 24418906 Free blocks: 480664715 Free inodes: 122101749 First block: 0 Block size: 4096 Fragment size: 4096 Reserved GDT blocks: 907 Blocks per group: 32768 Fragments per group: 32768 Inodes per group: 8192 Inode blocks per group: 512 Flex block group size: 16 Filesystem created: Mon Nov 14 20:43:23 2011 Last mount time: Mon Nov 14 20:43:55 2011 Last write time: Mon Nov 14 20:43:55 2011 Mount count: 1 Maximum mount count: 26 Last checked: Mon Nov 14 20:43:23 2011 Check interval: 15552000 (6 months) Next check after: Sat May 12 21:43:23 2012 Lifetime writes: 144 MB Reserved blocks uid: 0 (user root) Reserved blocks gid: 0 (group root) First inode: 11 Inode size: 256 Required extra isize: 28 Desired extra isize: 28 Journal inode: 8 Default directory hash: half_md4 Directory Hash Seed: 5e2619e2-7683-4589-b390-57e569444705 Journal backup: inode blocks Journal features: (none) Journal size: 128M Journal length: 32768 Journal sequence: 0x00002751 Journal start: 4341 [Details about groups 0-14904 omitted.]