From owner-freebsd-stable@FreeBSD.ORG Fri Feb 12 19:08:47 2010 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id EC983106566C; Fri, 12 Feb 2010 19:08:47 +0000 (UTC) (envelope-from rmacklem@uoguelph.ca) Received: from esa-annu.mail.uoguelph.ca (esa-annu.mail.uoguelph.ca [131.104.91.36]) by mx1.freebsd.org (Postfix) with ESMTP id 86BEE8FC13; Fri, 12 Feb 2010 19:08:47 +0000 (UTC) X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AvsEAGY2dUuDaFvI/2dsb2JhbACbAXS/b4JIghAEgxM X-IronPort-AV: E=Sophos;i="4.49,462,1262581200"; d="scan'208";a="65421611" Received: from darling.cs.uoguelph.ca ([131.104.91.200]) by esa-annu-pri.mail.uoguelph.ca with ESMTP; 12 Feb 2010 14:08:46 -0500 Received: from localhost (localhost.localdomain [127.0.0.1]) by darling.cs.uoguelph.ca (Postfix) with ESMTP id B4130940025; Fri, 12 Feb 2010 14:08:46 -0500 (EST) X-Virus-Scanned: amavisd-new at darling.cs.uoguelph.ca Received: from darling.cs.uoguelph.ca ([127.0.0.1]) by localhost (darling.cs.uoguelph.ca [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Wd+2klbPy29K; Fri, 12 Feb 2010 14:08:45 -0500 (EST) Received: from muncher.cs.uoguelph.ca (muncher.cs.uoguelph.ca [131.104.91.102]) by darling.cs.uoguelph.ca (Postfix) with ESMTP id AA20694010A; Fri, 12 Feb 2010 14:08:45 -0500 (EST) Received: from localhost (rmacklem@localhost) by muncher.cs.uoguelph.ca (8.11.7p3+Sun/8.11.6) with ESMTP id o1CJKA626707; Fri, 12 Feb 2010 14:20:11 -0500 (EST) X-Authentication-Warning: muncher.cs.uoguelph.ca: rmacklem owned process doing -bs Date: Fri, 12 Feb 2010 14:20:10 -0500 (EST) From: Rick Macklem X-X-Sender: rmacklem@muncher.cs.uoguelph.ca To: Dmitry Marakasov In-Reply-To: <20100212180032.GC94665@hades.panopticon> Message-ID: References: <201002102046.o1AKkrvj085173@lurza.secnetix.de> <20100212180032.GC94665@hades.panopticon> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: freebsd-hackers@FreeBSD.ORG, freebsd-stable@FreeBSD.ORG, Oliver Fromme Subject: Re: NFS write corruption on 8.0-RELEASE X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 12 Feb 2010 19:08:48 -0000 On Fri, 12 Feb 2010, Dmitry Marakasov wrote: > > Interesting, I'll try disabling it. However now I really wonder why > is such dangerous option available (given it's the cause) at all, > especially without a notice. Silent data corruption is possibly the > worst thing to happen ever. > I doubt that the data corruption you are seeing would be because of "soft". "soft" will cause various problems w.r.t. consistency, but in the case of a write through the buffer cache, I think it will leave the buffer dirty and eventually it will get another write attempt. > However, without soft option NFS would be a strange thing to use - > network problems is kinda inevitable thing, and having all processes > locked in a unkillable state (with hard mounts) when it dies is not > fun. Or am I wrong? > Well, using NFS over an unreliable network is going to cause grief sooner or later. The problem is that POSIX apps. don't expect I/O system calls to fail with EIO and generally don't handle that gracefully. For the future, I think "umount -F" (a forced dismount that accepts data loss) is the best compromise, since at least then a sysadmin knows that data corruption could have occurred when they do it and can choose to "wait" until the network is fixed as an alternative to the corruption? rick