From owner-freebsd-fs@FreeBSD.ORG Mon May 17 19:14:45 2004 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 2AFC716A4CE for ; Mon, 17 May 2004 19:14:45 -0700 (PDT) Received: from avgw.bjut.edu.cn (avgw.bjut.edu.cn [202.112.78.85]) by mx1.FreeBSD.org (Postfix) with SMTP id 2832C43D53 for ; Mon, 17 May 2004 19:14:44 -0700 (PDT) (envelope-from delphij@frontfree.net) Received: from beastie.frontfree.net ([218.107.145.7]) by avgw.bjut.edu.cn (SAVSMTP 3.1.5.43) with SMTP id M2004051810143415064 for ; Tue, 18 May 2004 10:14:34 +0800 Received: from localhost (localhost [127.0.0.1]) by beastie.frontfree.net (Postfix) with ESMTP id 9208C11B2B; Tue, 18 May 2004 10:14:35 +0800 (CST) Received: from beastie.frontfree.net ([127.0.0.1]) by localhost (beastie.frontfree.net [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 00866-03; Tue, 18 May 2004 10:14:35 +0800 (CST) Received: by beastie.frontfree.net (Postfix, from userid 1001) id 1267011C01; Tue, 18 May 2004 10:14:34 +0800 (CST) Date: Tue, 18 May 2004 10:14:33 +0800 From: Xin LI To: Julian Elischer Message-ID: <20040518021433.GA969@frontfree.net> References: <20040517174836.GA983@frontfree.net> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="OXfL5xGRrasGEqWY" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.1i X-GPG-key-ID/Fingerprint: 0xCAEEB8C0 / 43B8 B703 B8DD 0231 B333 DC28 39FB 93A0 CAEE B8C0 X-GPG-Public-Key: http://www.delphij.net/delphij.asc X-Operating-System: FreeBSD beastie.frontfree.net 5.2-CURRENT FreeBSD 5.2-CURRENT #33: Mon Apr 26 15:10:21 CST 2004 delphij@beastie.frontfree.net:/usr/obj/usr/src/sys/BEASTIE i386 X-URL: http://www.delphij.net X-By: delphij@beastie.frontfree.net X-Location: Beijing, China X-Virus-Scanned: by amavisd-new at frontfree.net cc: freebsd-fs@freebsd.org cc: Mikhail Teterin Subject: Re: QMail and SoftUpdates X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 18 May 2004 02:14:45 -0000 --OXfL5xGRrasGEqWY Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, May 17, 2004 at 01:25:04PM -0700, Julian Elischer wrote: [...] > Softupdates is NOT unsafe for this task IF the app does an fsync() > before acknowldging the incoming mail. Fsync under Soft updates will not > return until all data and metadata associated with the file > has been written to disk. This will make the write as slow as a sync=20 > munted filesystem, but all other writes on the disk will proceeed at=20 > soft-updates speed. Oh... I missed this point, sorry. Your statement is more accurate, thanks for pointing this out :-) I think it should be noted that on ATA drives, the hardware writing cache (without an acknowledge back to the operating system when the data is actually written to the disk, like on a tagged queue enabled SCSI disk), is enabled by default. This will greatly disturb SoftUpdates' work and may lead to data loss even when the application is correctly doing fsync(), because with ATA hardware writing cache, the disk will "cheat" the opearting system - Before the data actually goes to disk, it tells that it is, and data is lost if crash occours here. Cheers, --=20 Xin LI http://www.delphij.net/ See complete headers for GPG key and other information. --OXfL5xGRrasGEqWY Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.4 (FreeBSD) iD8DBQFAqXGJOfuToMruuMARAmBRAKCBpWLq9SP/t+Lsot9Qs/ROEoTR+ACfWYC7 pO2JHcyfttpmHzlBSGTx1VU= =b0g2 -----END PGP SIGNATURE----- --OXfL5xGRrasGEqWY--