From owner-freebsd-questions@FreeBSD.ORG  Mon Feb 22 17:36:39 2010
Return-Path: <owner-freebsd-questions@FreeBSD.ORG>
Delivered-To: questions@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 6689C106566C
	for <questions@freebsd.org>; Mon, 22 Feb 2010 17:36:39 +0000 (UTC)
	(envelope-from jerrymc@gizmo.acns.msu.edu)
Received: from gizmo.acns.msu.edu (gizmo.acns.msu.edu [35.8.1.43])
	by mx1.freebsd.org (Postfix) with ESMTP id 2A4338FC12
	for <questions@freebsd.org>; Mon, 22 Feb 2010 17:36:38 +0000 (UTC)
Received: from gizmo.acns.msu.edu (localhost [127.0.0.1])
	by gizmo.acns.msu.edu (8.13.6/8.13.6) with ESMTP id o1MHY7iE044771;
	Mon, 22 Feb 2010 12:34:07 -0500 (EST)
	(envelope-from jerrymc@gizmo.acns.msu.edu)
Received: (from jerrymc@localhost)
	by gizmo.acns.msu.edu (8.13.6/8.13.6/Submit) id o1MHY7Qr044770;
	Mon, 22 Feb 2010 12:34:07 -0500 (EST) (envelope-from jerrymc)
Date: Mon, 22 Feb 2010 12:34:07 -0500
From: Jerry McAllister <jerrymc@msu.edu>
To: Aiza <aiza21@comclark.com>
Message-ID: <20100222173407.GA44738@gizmo.acns.msu.edu>
References: <4B80ABBA.9000707@comclark.com>
	<20100221061449.GK70798@dan.emsphone.com>
	<4B80E4AF.3040204@comclark.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <4B80E4AF.3040204@comclark.com>
User-Agent: Mutt/1.4.2.2i
Cc: freebsd-questions <questions@freebsd.org>,
	Dan Nelson <dnelson@allantgroup.com>
Subject: Re: Dump questions
X-BeenThere: freebsd-questions@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: User questions <freebsd-questions.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>, 
	<mailto:freebsd-questions-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-questions>
List-Post: <mailto:freebsd-questions@freebsd.org>
List-Help: <mailto:freebsd-questions-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>, 
	<mailto:freebsd-questions-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Mon, 22 Feb 2010 17:36:39 -0000

On Sun, Feb 21, 2010 at 03:45:51PM +0800, Aiza wrote:

> Dan Nelson wrote:
> >In the last episode (Feb 21), Aiza said:
> >>1. Using the -L flag to create a snapshot of the
> >>live running file system.
> >>
> >>Does this mean that a complete copy of the file
> >>system is written to .snap directory?
> >
> >No; that would be a "copy".  Snapshots only copy blocks as they are 
> >modified
> >on the parent filesystem, so their size is determined by how much data is
> >modified since the snapshot was created.
> >
> So how does this interact with the dump process?
> 
> Dump start reading and writing its dump file and as the live system 
> changes the changes are written to the .snap and when dump completes it 
> overwrites it dump with the changes from the .snap???

No.

> 
> How does this process work in detail?

Go back and read the good and quite complete description someone put
in about how snapshotting works a while back in this thread.  I think
it was Matthew Seaman, but I don't remember for sure.

////jerry


> _______________________________________________
> freebsd-questions@freebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-questions
> To unsubscribe, send any mail to "freebsd-questions-unsubscribe@freebsd.org"