From owner-freebsd-arch  Sun Mar 31 22: 8: 4 2002
Delivered-To: freebsd-arch@freebsd.org
Received: from beastie.mckusick.com (beastie.mckusick.com [209.31.233.184])
	by hub.freebsd.org (Postfix) with ESMTP id D414C37B400
	for <arch@FreeBSD.ORG>; Sun, 31 Mar 2002 22:07:59 -0800 (PST)
Received: from beastie.mckusick.com (localhost [127.0.0.1])
	by beastie.mckusick.com (8.11.6/8.11.6) with ESMTP id g31678D07951;
	Sun, 31 Mar 2002 22:07:08 -0800 (PST)
	(envelope-from mckusick@beastie.mckusick.com)
Message-Id: <200204010607.g31678D07951@beastie.mckusick.com>
To: Garance A Drosihn <drosih@rpi.edu>
Subject: Re: UFS snapshots in current 
Cc: arch@FreeBSD.ORG
In-Reply-To: Your message of "Sun, 31 Mar 2002 21:12:13 EST."
             <p05101501b8cd700e7c76@[128.113.24.47]> 
Date: Sun, 31 Mar 2002 22:07:08 -0800
From: Kirk McKusick <mckusick@beastie.mckusick.com>
Sender: owner-freebsd-arch@FreeBSD.ORG
Precedence: bulk
List-ID: <freebsd-arch.FreeBSD.ORG>
List-Archive: <http://docs.freebsd.org/mail/> (Web Archive)
List-Help: <mailto:majordomo@FreeBSD.ORG?subject=help> (List Instructions)
List-Subscribe: <mailto:majordomo@FreeBSD.ORG?subject=subscribe%20freebsd-arch>
List-Unsubscribe: <mailto:majordomo@FreeBSD.ORG?subject=unsubscribe%20freebsd-arch>
X-Loop: FreeBSD.ORG

	Date: Sun, 31 Mar 2002 21:12:13 -0500
	To: Kirk McKusick <mckusick@beastie.mckusick.com>
	From: Garance A Drosihn <drosih@rpi.edu>
	Subject: Re: UFS snapshots in current
	Cc: arch@FreeBSD.ORG

	At 2:14 PM -0800 3/31/02, Kirk McKusick wrote:

	>On your final question about making a pax archive, if you make
	>an archive of the real filesystem, the snapshot will show up
	>on the archive as a file the size of the filesystem partition.
	>If you mount the snapshot and then make an archive of that
	>filesystem, then the snapshot(s) in the archive will show up
	>as zero length files.

	Hmm.  Is there any way for a regular user-land process to tell
	if a given file is a snapshot?  Something in the stat() info,
	or some other way to tell?  I have no urgent need for it, but
	it seems like it would be useful.

	-- 
	Garance Alistair Drosehn            =   gad@eclipse.acs.rpi.edu
	Senior Systems Programmer           or  gad@freebsd.org
	Rensselaer Polytechnic Institute    or  drosih@rpi.edu

You can determine if a file is a snapshot by doing a stat
and checking for the SF_SNAPSHOT bit being set in the
st_flags field.

	Kirk McKusick

To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-arch" in the body of the message