From owner-freebsd-questions@FreeBSD.ORG Tue May 6 12:06:35 2003 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 9920437B401 for ; Tue, 6 May 2003 12:06:35 -0700 (PDT) Received: from pa-plum1b-166.pit.adelphia.net (pa-plum1a-215.pit.adelphia.net [24.53.170.215]) by mx1.FreeBSD.org (Postfix) with ESMTP id 8511743FA3 for ; Tue, 6 May 2003 12:06:34 -0700 (PDT) (envelope-from wmoran@potentialtech.com) Received: from potentialtech.com (working [172.16.0.95]) h46J6X0n008939; Tue, 6 May 2003 15:06:33 -0400 (EDT) (envelope-from wmoran@potentialtech.com) Message-ID: <3EB807B9.4070603@potentialtech.com> Date: Tue, 06 May 2003 15:06:33 -0400 From: Bill Moran User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.3) Gecko/20030429 X-Accept-Language: en-us, en MIME-Version: 1.0 To: YOU References: In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit cc: questions@freebsd.org Subject: Re: Realtime Filesystem Replication X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 06 May 2003 19:06:36 -0000 YOU wrote: > Thanks so far to the suggestions including rsync and unison. Both appear > to be triggered upon a command line or user typed command. Is someone > using a system that tracks the mtimes for files and updates without > prompt? Are you sure you really need _realtime_? That's a pretty tall order, and I don't know of anything that can provide it. OTOH, with rsync as a cron job, you can easily mirror a large amount of data, say, every 5 minutes. If a 5-minute lag in data replication is acceptable, I would recommend using rsync instead of looking for something more "real time". I don't know if any true "real time" synchronizing exists. Let me ask you a few questions: 1. What is the maximum acceptable "lag" for data replication? 2. How much data do you estimate there will be? (both megs and # of files) 3. How often do you estimate the data will change? If 1 is longer than a few minutes, and 2 and 3 aren't terribly demanding, rsync is probably the way to go. On a related note: I had an idea that you should be able to create some sort of network RAID using the new GEOM system. Something that would allow everything that was written to a local filsystem to also be mirrored via NFS to another system. I haven't had a chance to do anything more than dream about it, though. -- Bill Moran Potential Technologies http://www.potentialtech.com