From owner-freebsd-fs@FreeBSD.ORG Sat Apr 12 20:54:48 2003 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 F199837B401 for ; Sat, 12 Apr 2003 20:54:47 -0700 (PDT) Received: from bilver.wjv.com (user38.net339.fl.sprint-hsd.net [65.40.24.38]) by mx1.FreeBSD.org (Postfix) with ESMTP id A431343F75 for ; Sat, 12 Apr 2003 20:54:46 -0700 (PDT) (envelope-from bv@wjv.com) Received: from bilver.wjv.com (localhost.wjv.com [127.0.0.1]) by bilver.wjv.com (8.12.9/8.12.9) with ESMTP id h3D3sRab073568 for ; Sat, 12 Apr 2003 23:54:29 -0400 (EDT) (envelope-from bv@wjv.com) Received: (from bv@localhost) by bilver.wjv.com (8.12.9/8.12.9/Submit) id h3D3sRPY073550 for freebsd-fs@freebsd.org; Sat, 12 Apr 2003 23:54:27 -0400 (EDT) Date: Sat, 12 Apr 2003 23:54:25 -0400 From: Bill Vermillion To: freebsd-fs@freebsd.org Message-ID: <20030413035425.GA681@wjv.com> References: <20030412172455.GA85377@woodstock.nethamilton.net> <20030412185346.GB52650@wjv.com> <20030412231802.GB85377@woodstock.nethamilton.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20030412231802.GB85377@woodstock.nethamilton.net> Organization: W.J.Vermillion / Orlando - Winter Park ReplyTo: bv@wjv.com User-Agent: Mutt/1.5.1i X-Spam-Status: No, hits=-3.3 required=5.0 tests=IN_REP_TO,NIGERIAN_TRANSACTION_1,NOSPAM_INC, QUOTED_EMAIL_TEXT,REFERENCES,SPAM_PHRASE_01_02,USER_AGENT, USER_AGENT_MUTT version=2.43 Subject: Re: PATCH: Forcible delaying of UFS (soft)updates X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list Reply-To: bv@wjv.com List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 13 Apr 2003 03:54:48 -0000 Throwing caution to the wind and speaking without thinking about what was being said on Sat, Apr 12, 2003 at 18:18 , Jon Hamilton blurted this: > Bill Vermillion , said on Sat Apr 12, 2003 [02:53:46 PM]: > } In the last exciting episode of the Jon Hamilton saga > } on Sat, Apr 12, 2003 at 12:24 , Jon Hamilton as heard to say: > } > Dave Hart , said on Sat Apr 12, 2003 [04:58:13 PM]: > } > } Marko Zec said: > } > [...] > } > } > If the disk would start spinning every now and than, > } > } > the whole patch would than become pointless... > } > } > } As I feared. > } > } > [...] the fact that the modified fsync() just returns > } > } > without doing anything useful doesn't mean the data will be > } > } > lost - it will simply be delayed until the next coalesced > } > } > updating occurs. > } > } Unless, of course, your system or power happens to fail. > } > } Imagine you have a database program keeping track of banking > } > } transactions. This program uses fsync() to ensure its > } > } transaction logs are committed to reliable storage before > } > } indicating the transaction is completed. Suppose the moment > } > } after I withdraw $500 from an ATM, the operating system or > } > } hardware fails at the bank. > } > Right. So in such a situation, the admin for that system would not > } > enable this optional behavior. There probably aren't too many cases > } > where mission critical financial transaction systems run on a laptop > } > on which the desire is maximal battery life, which is the case from > } > which this whole patch/discussion derives. It's a conscious tradeoff. > } I think 'the admin could enable this optional behaviour' is the > } wrong approach. > } I think it should be for laptops the admin could >disable< the > } feature. By default make everyting as robust and failsafe as > } possible. > I agree, and that's what I said. Unfortunately, I wasn't overly clear > about it. The optional behavior would be the _enabling_ of the patch > behavior. I feel better about it already :-) Thanks for the clarification. Bill -- Bill Vermillion - bv @ wjv . com