From: Theodore Ts'o <tytso@mit.edu>
To: Subranshu Patel <spatel.ml@gmail.com>
Cc: linux-ext4@vger.kernel.org
Subject: Re: Dumpe2fs output with primary and backup superblock are different?
Date: Thu, 16 Jan 2014 11:35:34 -0500 [thread overview]
Message-ID: <20140116163534.GA32391@thunk.org> (raw)
In-Reply-To: <CAEUQcegq-ZmgJ2Cr+jqr=1HiOK+NqnvBoxH0JQ3fTYXOd+Z83g@mail.gmail.com>
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
prev parent reply other threads:[~2014-01-16 16:35 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-16 10:44 Dumpe2fs output with primary and backup superblock are different? Subranshu Patel
2014-01-16 16:35 ` Theodore Ts'o [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20140116163534.GA32391@thunk.org \
--to=tytso@mit.edu \
--cc=linux-ext4@vger.kernel.org \
--cc=spatel.ml@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).