From: Theodore Ts'o Subject: Re: Dumpe2fs output with primary and backup superblock are different? Date: Thu, 16 Jan 2014 11:35:34 -0500 Message-ID: <20140116163534.GA32391@thunk.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-ext4@vger.kernel.org To: Subranshu Patel Return-path: Received: from imap.thunk.org ([74.207.234.97]:49087 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752078AbaAPQfi (ORCPT ); Thu, 16 Jan 2014 11:35:38 -0500 Content-Disposition: inline In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: On Thu, Jan 16, 2014 at 04:14:14PM +0530, Subranshu Patel wrote: > I am using dumpe2fs command using primary superblock (default) and > backup superblock. In both the cases the output is different. Yes, this is expected. It's too expensive to be constantly updating all of the backup block group descriptors every time we allocate or deallocate a block or inode. What is important to be kept in the backup block group descriptors is where to find the inode table and allocation bitmaps. E2fsck can reconstruct the information which is not updated in the backup block group descriptors and backup superblock, and that's what you are seeing which is different. Regards, - Ted