From owner-freebsd-stable@FreeBSD.ORG Mon Apr 28 08:41:15 2003 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 2E57A37B401 for ; Mon, 28 Apr 2003 08:41:15 -0700 (PDT) Received: from apollo.backplane.com (apollo.backplane.com [216.240.41.2]) by mx1.FreeBSD.org (Postfix) with ESMTP id AE77143F93 for ; Mon, 28 Apr 2003 08:41:14 -0700 (PDT) (envelope-from dillon@apollo.backplane.com) Received: from apollo.backplane.com (localhost [127.0.0.1]) by apollo.backplane.com (8.12.9/8.12.6) with ESMTP id h3SFfAVI045686; Mon, 28 Apr 2003 08:41:11 -0700 (PDT) (envelope-from dillon@apollo.backplane.com) Received: (from dillon@localhost) by apollo.backplane.com (8.12.9/8.12.6/Submit) id h3SFfARi045685; Mon, 28 Apr 2003 08:41:10 -0700 (PDT) Date: Mon, 28 Apr 2003 08:41:10 -0700 (PDT) From: Matthew Dillon Message-Id: <200304281541.h3SFfARi045685@apollo.backplane.com> To: Geoffroy Desvernay References: <3EAD48E8.2020401@esm2.imt-mrs.fr> cc: freebsd-stable@freebsd.org Subject: Re: sharing scsi disk beetween two freesbd's ... X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 28 Apr 2003 15:41:15 -0000 :This is a cryptographically signed message in MIME format. : :--------------ms000201080102020100060303 :Content-Type: text/plain; charset=ISO-8859-15; format=flowed :Content-Transfer-Encoding: 7bit : :I want to use one scsi disk with two redondant servers, mounted r/w on server A and r/o on :server B. :Everything works, except that when I write data from server A, I can't read it on server B :before un-mounting the disk ant re-mounting it... (with AND without soft-updates) : :Is there any way to mount a disk r/o keeping in sync with real disk data ? : :Thank you. : :-- :Geoffroy DESVERNAY The machines cache the disk data in memory, so if one machine has read a track and the second machine writes it, the first machine will not see the changes until it flushes its caches (which may be never). Also, what you are doing is extremely dangerous. Even the machine with the read-only mount is going to assume that the data on the disk is not going to change out from under it, and when it does you could crash the kernel. A better solution would be to attach the disk to a single machine and then export the filesystem to the second machine via NFS. -Matt