From: Theodore Ts'o <tytso@mit.edu>
To: Jitesh Shah <jitesh.1337@gmail.com>
Cc: linux-ext4@vger.kernel.org
Subject: Re: Reproducible block structure
Date: Tue, 10 Dec 2013 08:42:55 -0500 [thread overview]
Message-ID: <20131210134255.GA31214@thunk.org> (raw)
In-Reply-To: <CAO_9QQcOSgUA84ewb=PANikU+MzeTmmeHnPeLd2SHQ_46sUi8Q@mail.gmail.com>
On Mon, Dec 09, 2013 at 09:03:23PM -0800, Jitesh Shah wrote:
>
> Now, if the script is ran in the SAME way for all 5 HDDs, is it
> guaranteed that these HDDs will be same at the block level too? (i.e.
> block allocation/deallocation will follow the same pattern). Assume
> single-core system with only one process modifying the HDD in
> predetermined order.
Nope, there's no way to guarantee this. There are a few places where
the algorithms are non-deterministic by design. It would be possible
to make some changes to guarantee this, but I'm not sure it's really
worth it --- in real life, assuming a single core system with a single
process which is also single threaded is generally not a realisstic
scenario.
> Why do I ask -> I am tinkering with the idea of block level
> verification of images. If the above guarantees can be provided, I can
> easily hash the raw HDD for verification purposes.
If you want to do a block level verification of the image, why not
also do block level update of the image as well?
Regards,
- Ted
next prev parent reply other threads:[~2013-12-10 13:43 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-10 5:03 Reproducible block structure Jitesh Shah
2013-12-10 13:32 ` Carlos Maiolino
2013-12-10 13:42 ` Theodore Ts'o [this message]
2013-12-10 18:08 ` Jitesh Shah
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=20131210134255.GA31214@thunk.org \
--to=tytso@mit.edu \
--cc=jitesh.1337@gmail.com \
--cc=linux-ext4@vger.kernel.org \
/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