From owner-freebsd-fs@FreeBSD.ORG Thu Mar 17 13:50:28 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 448FC1065673 for ; Thu, 17 Mar 2011 13:50:28 +0000 (UTC) (envelope-from freebsd-fs@m.gmane.org) Received: from lo.gmane.org (lo.gmane.org [80.91.229.12]) by mx1.freebsd.org (Postfix) with ESMTP id ED5F08FC14 for ; Thu, 17 Mar 2011 13:50:27 +0000 (UTC) Received: from list by lo.gmane.org with local (Exim 4.69) (envelope-from ) id 1Q0Das-0007wS-6N for freebsd-fs@freebsd.org; Thu, 17 Mar 2011 14:50:26 +0100 Received: from lara.cc.fer.hr ([161.53.72.113]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Thu, 17 Mar 2011 14:50:26 +0100 Received: from ivoras by lara.cc.fer.hr with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Thu, 17 Mar 2011 14:50:26 +0100 X-Injected-Via-Gmane: http://gmane.org/ To: freebsd-fs@freebsd.org From: Ivan Voras Date: Thu, 17 Mar 2011 14:50:07 +0100 Lines: 24 Message-ID: References: <20110317071618.GB49199@blazingdot.com> <20110317074558.GA2248@icarus.home.lan> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Complaints-To: usenet@dough.gmane.org X-Gmane-NNTP-Posting-Host: lara.cc.fer.hr User-Agent: Mozilla/5.0 (X11; U; FreeBSD amd64; en-US; rv:1.9.2.12) Gecko/20101102 Thunderbird/3.1.6 In-Reply-To: <20110317074558.GA2248@icarus.home.lan> X-Enigmail-Version: 1.1.2 Subject: Re: ZFS vfs.zfs.cache_flush_disable and ZIL reliability 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: Thu, 17 Mar 2011 13:50:28 -0000 On 17/03/2011 08:45, Jeremy Chadwick wrote: > General question to users and/or developers: > > Can someone please explain to me why people are so horribly focused (I > would go as far to say OCD) on this topic? For me, it's a matter of statistics; if this can improve the chances of data surviving by (just guessing here) 10%, it might be worth it. > Won't there *always* be some degree of potential loss of data in the > above two circumstances? Shouldn't the concern be less about "how much > data just got lost" and more about "is the filesystem actually usable > and clean/correct?" (ZFS implements the latter two assuming you're > using mirror or raidz). As an admin, I'd much rather have a file system that's clean with some data lost, but as a user I think I would be unhappy with any data loss :) Backups still rule. ZFS is covered (presumably, as I don't really get from the code how it's supposed to work - any clarification for pjd@, mm@ and others would be appreciated) and I've talked with McKusick about BIO_FLUSH in UFS and it will happen as soon as I have the time to follow up.