From owner-freebsd-fs@FreeBSD.ORG Tue Jun 21 10:51:42 2011 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id EB8641065677 for ; Tue, 21 Jun 2011 10:51:42 +0000 (UTC) (envelope-from peterjeremy@acm.org) Received: from fallbackmx09.syd.optusnet.com.au (fallbackmx09.syd.optusnet.com.au [211.29.132.242]) by mx1.freebsd.org (Postfix) with ESMTP id B77FD8FC08 for ; Tue, 21 Jun 2011 10:51:40 +0000 (UTC) Received: from mail18.syd.optusnet.com.au (mail18.syd.optusnet.com.au [211.29.132.199]) by fallbackmx09.syd.optusnet.com.au (8.13.1/8.13.1) with ESMTP id p5L8lBoO003556 for ; Tue, 21 Jun 2011 18:47:11 +1000 Received: from server.vk2pj.dyndns.org (c220-239-116-103.belrs4.nsw.optusnet.com.au [220.239.116.103]) by mail18.syd.optusnet.com.au (8.13.1/8.13.1) with ESMTP id p5L8kovw024987 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Tue, 21 Jun 2011 18:46:52 +1000 X-Bogosity: Ham, spamicity=0.000000 Received: from server.vk2pj.dyndns.org (localhost.vk2pj.dyndns.org [127.0.0.1]) by server.vk2pj.dyndns.org (8.14.4/8.14.4) with ESMTP id p5L8kn12068893; Tue, 21 Jun 2011 18:46:49 +1000 (EST) (envelope-from peter@server.vk2pj.dyndns.org) Received: (from peter@localhost) by server.vk2pj.dyndns.org (8.14.4/8.14.4/Submit) id p5L8kjfu068892; Tue, 21 Jun 2011 18:46:45 +1000 (EST) (envelope-from peter) Date: Tue, 21 Jun 2011 18:46:45 +1000 From: Peter Jeremy To: Kirk McKusick Message-ID: <20110621084645.GA68018@server.vk2pj.dyndns.org> References: <20110617153415.GA92803@testsoekris.hotsoft.nl> <201106171842.p5HIgQjn018296@chez.mckusick.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="lrZ03NoBR/3+SXJZ" Content-Disposition: inline In-Reply-To: <201106171842.p5HIgQjn018296@chez.mckusick.com> X-PGP-Key: http://members.optusnet.com.au/peterjeremy/pubkey.asc User-Agent: Mutt/1.5.21 (2010-09-15) Cc: freebsd-fs@freebsd.org, Jeff Roberson Subject: Re: SU+J: negative used diskspace (for a while) X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 21 Jun 2011 10:51:43 -0000 --lrZ03NoBR/3+SXJZ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2011-Jun-17 11:42:26 -0700, Kirk McKusick wrote: >> Date: Fri, 17 Jun 2011 17:34:15 +0200 >> From: Hans Ottevanger >> So it takes more than a minute before the disk space is back to "normal" >> values. >We used to account for deleted blocks at the instant that they were >removed. This accounting was rather complex, so as part of doing >SU+J, Jeff simplified it. Under the simplification, the removal is >not accounted for until part way through the removal process. The >result is that you now get these false negative block counts until >the blocks have been partially reclaimed. If this behavior causes >enough trouble, Jeff might be convinced that the more accurate block >accounting is necessary. Negative values may also impact NFS clients - though just limiting the reported used space to 0 should avoid them getting too upset. That said, whilst I haven't seen negative used values, ZFS and Solaris UFS also take an extended period before 'df' reports correct values (several minutes for Solaris UFS). In the case of ZFS, even 'du' can report incorrect information for a while. --=20 Peter Jeremy --lrZ03NoBR/3+SXJZ Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.17 (FreeBSD) iEYEARECAAYFAk4AWnUACgkQ/opHv/APuIecHgCdEPSaZIABGsfWByKiNV6jlg2A 7SoAoMNHZQsYAjdgV+R9cs/vQ/udpXBX =Ddxw -----END PGP SIGNATURE----- --lrZ03NoBR/3+SXJZ--