From owner-freebsd-current@FreeBSD.ORG Mon Jul 26 21:13:06 2004 Return-Path: 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 AD18516A4CE; Mon, 26 Jul 2004 21:13:06 +0000 (GMT) Received: from mail.dt.e-technik.uni-dortmund.de (mail.dt.e-technik.Uni-Dortmund.DE [129.217.163.1]) by mx1.FreeBSD.org (Postfix) with ESMTP id 634D243D3F; Mon, 26 Jul 2004 21:13:06 +0000 (GMT) (envelope-from ma@dt.e-technik.uni-dortmund.de) Received: from m2a2.dyndns.org (p5487CB64.dip.t-dialin.net [84.135.203.100]) 4B46B36399; Mon, 26 Jul 2004 23:13:05 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by merlin.emma.line.org (Postfix) with ESMTP id 9E38AC6205; Mon, 26 Jul 2004 23:13:04 +0200 (CEST) Received: from merlin.emma.line.org ([127.0.0.1]) by localhost (m2a2.dyndns.org [127.0.0.1]) (amavisd-new, port 10024) with LMTP id 25296-01; Mon, 26 Jul 2004 23:13:03 +0200 (CEST) Received: by merlin.emma.line.org (Postfix, from userid 500) id A6332C18AF; Mon, 26 Jul 2004 23:13:03 +0200 (CEST) To: Scott Long In-Reply-To: <20040726121005.D32601@pooker.samsco.org> (Scott Long's message of "Mon, 26 Jul 2004 12:15:02 -0600 (MDT)") References: <1090718450.2020.4.camel@illusion.com> <200407251112.46183.doconnor@gsoft.com.au> <20040726152151.GC1473@green.homeunix.org> <20040726175219.GA96815@green.homeunix.org> <20040726121005.D32601@pooker.samsco.org> From: Matthias Andree Date: Mon, 26 Jul 2004 23:13:03 +0200 Message-ID: User-Agent: Gnus/5.110003 (No Gnus v0.3) Emacs/21.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Virus-Scanned: by amavisd-new at m2a2.dyndns.org cc: current@freebsd.org cc: bugghy Subject: Re: magic sysrq keys functionality X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 26 Jul 2004 21:13:06 -0000 Scott Long writes: > GAH! No, please don't start this war again! The last time that we tried > turning this off in a release (4.1 IIRC), were were plagqued by months of > earthquakes, plagues, and deaths of first-born youngsters. I 100% agree > that write caching in ATA is not compatible with data integrety, but the > ATA marketting machine has convinced us that cached+untagged speed is > better than uncached+tagged safety. C'est la vie, or so they say here. Looking out of the cosy FreeBSD hut, for the Linux kernel, write barrier support (i. e. using the ATA cache flush facility on those drives that support it, and logging a warning if a drive doesn't) to enforce proper write order and synchronization is underway, with some distros already using it, for instance SuSE. It's not yet in the baseline code AFAIK. BTW, is proper write order guaranteed on SCSI drives through ordered tags? softdep doesn't really like blocks being written in different order than scheduled. -- Matthias Andree Encrypted mail welcome: my GnuPG key ID is 0x052E7D95 (PGP/MIME preferred)