From: Christoph Anton Mitterer Subject: Re: mounting ext3 with another superblock doesn't =?UTF-8?Q?work=3F?= Date: Mon, 09 May 2011 13:47:41 +0000 Message-ID: References: <031c613316176c32f09748706a086be2@imap.dd24.net> <23AF51ED-8130-4401-94FE-93CF36E8E1C1@dilger.ca> <6f43bed530a6412344f7b30e42a89d23@imap.dd24.net> <20110509120608.GK4122@quack.suse.cz> <1304945969.11788.14.camel@heisenberg.scientia.net> <20110509131027.GM4122@quack.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Cc: , To: Jan Kara Return-path: Received: from mailgw01.dd24.net ([193.46.215.41]:47160 "EHLO mailgw01.dd24.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752802Ab1EINsL (ORCPT ); Mon, 9 May 2011 09:48:11 -0400 In-Reply-To: <20110509131027.GM4122@quack.suse.cz> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Mon, 9 May 2011 15:10:27 +0200, Jan Kara wrote: > Well, the block size is most likely the same (4 KB) in both the old and > the new fs (unless you tinkered with it but I don't expect that). That > defines size of a block group and thus position of inodes, bitmaps, etc. > Another variable is a number of inodes (per group). If you have an old > superblock you can compare the old and the new number of inodes and you > can be sure. Otherwise you rely on whether the math in the mkfs with which > you've originally created the fs is the same as the math in your current > mkfs (and you didn't specify any special options regarding this)... Well I didn't change them but maybe Debian has modified the defaults in mke2fs.conf since I created the fs initially. inode_size = 256 could be a candidate. Unfortunately I don't remember which Debian/e2fsprogs I've used to create the fs originally. Was this ever set to 128 (i mean as a default for e2fsprogs itself, when it was not set in mke2fs.conf)? If the values would have actually changed, wouldn't this mean that all data was then gone? Cheers, Chris