From owner-freebsd-current@FreeBSD.ORG  Sat Jul  3 08:05:24 2004
Return-Path: <owner-freebsd-current@FreeBSD.ORG>
Delivered-To: freebsd-current@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP
	id CAC2616A4CF; Sat,  3 Jul 2004 08:05:22 +0000 (GMT)
Received: from mailout2.pacific.net.au (mailout2.pacific.net.au [61.8.0.85])
	by mx1.FreeBSD.org (Postfix) with ESMTP
	id 49F0043D2F; Sat,  3 Jul 2004 08:05:22 +0000 (GMT)
	(envelope-from bde@zeta.org.au)
Received: from mailproxy1.pacific.net.au (mailproxy1.pacific.net.au
	[61.8.0.86])i6385L5v028109;	Sat, 3 Jul 2004 18:05:21 +1000
Received: from gamplex.bde.org (katana.zip.com.au [61.8.7.246])
	i6385Jao014791;	Sat, 3 Jul 2004 18:05:20 +1000
Date: Sat, 3 Jul 2004 18:05:18 +1000 (EST)
From: Bruce Evans <bde@zeta.org.au>
X-X-Sender: bde@gamplex.bde.org
To: "Kenneth D. Merry" <ken@freebsd.org>
In-Reply-To: <20040703171141.T7639@gamplex.bde.org>
Message-ID: <20040703175702.M7724@gamplex.bde.org>
References: <20040702163759.GA41401@panzer.kdm.org>
	<20040702192335.GA42513@panzer.kdm.org>
	<20040703171141.T7639@gamplex.bde.org>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
cc: current@freebsd.org
Subject: Re: UFS2 filesystem and filesize limits
X-BeenThere: freebsd-current@freebsd.org
X-Mailman-Version: 2.1.1
Precedence: list
List-Id: Discussions about the use of FreeBSD-current
	<freebsd-current.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>,
	<mailto:freebsd-current-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-current>
List-Post: <mailto:freebsd-current@freebsd.org>
List-Help: <mailto:freebsd-current-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>,
	<mailto:freebsd-current-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sat, 03 Jul 2004 08:05:24 -0000

On Sat, 3 Jul 2004, Bruce Evans wrote:

> On Fri, 2 Jul 2004, Kenneth D. Merry wrote:
>
> > On Fri, Jul 02, 2004 at 10:37:59 -0600, Kenneth D. Merry wrote:
> > >
> > > I've searched a bit on the list archives, but didn't find an obvious answer
> > > so I thought I'd ask:
> > >
> > > What is the maximum possible size of a UFS2 filesystem?  Are there any
> > > gotchas associated with going that large?
> > >
> > > What is the maximum possible file size on a UFS2 filesystem?
>
> It is given by the same formula as for any ffs file system.  The main limit
> ...

Forgot to answer the first question.  I think the maximum possible size for
an ffs file system is supposed to limited only by block addressibility.  So
for ffs1 the limit is 2**31 * <logical block size> and for ffs2 it is
2**63 * <logical block size>.  The latter is much larger than other
implementation-specific limits, so it is no limit at all.  FreeBSD has
OFF_MAX = 2**63 - 1.  FreeBSD-[2-4] has a device access limit of 2**31
DEV_BSIZE blocks = 1TB.  FreeBSD-5 has a device access limit of 2**63
DEV_BSIZE blocks = larger than OFF_MAX, so not the limit (but since
DEV_BSIZE is usually smaller than <logical block size>, this limit would
be the effective one in other implementations).

Bruce