From owner-freebsd-current@FreeBSD.ORG Thu May 26 18:07:33 2005 Return-Path: X-Original-To: freebsd-current@freebsd.org Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id CA0C216A41C for ; Thu, 26 May 2005 18:07:33 +0000 (GMT) (envelope-from anderson@centtech.com) Received: from mh2.centtech.com (moat3.centtech.com [207.200.51.50]) by mx1.FreeBSD.org (Postfix) with ESMTP id D0B3643D58 for ; Thu, 26 May 2005 18:07:32 +0000 (GMT) (envelope-from anderson@centtech.com) Received: from [10.177.171.220] (neutrino.centtech.com [10.177.171.220]) by mh2.centtech.com (8.13.1/8.13.1) with ESMTP id j4QI7Uc4054012; Thu, 26 May 2005 13:07:30 -0500 (CDT) (envelope-from anderson@centtech.com) Message-ID: <42961053.2060900@centtech.com> Date: Thu, 26 May 2005 13:07:15 -0500 From: Eric Anderson User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.7.7) Gecko/20050504 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Bjoern Koenig References: <4295D51F.50106@centtech.com> <429606D9.6080602@cs.tu-berlin.de> <42960ACB.7090801@cs.tu-berlin.de> <42960CFE.4060307@centtech.com> <42960EE7.30607@cs.tu-berlin.de> In-Reply-To: <42960EE7.30607@cs.tu-berlin.de> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: FreeBSD Current Subject: Re: Disable read/write caching to disk? X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 26 May 2005 18:07:33 -0000 Bjoern Koenig wrote: > Eric Anderson wrote: > >> Bjoern Koenig wrote: >> >> Thanks.. I've just read (quickly) both man pages. It seems as though >> you are suggesting disabling the physical disk caching, which should >> not make a difference in my case. The disk would report whatever it >> needs to report to either host, and those should be in sync. > > > Oh, I'm sorry. I have misunderstood you then. > >> When I mount the filesystem on host B ro, it shows me the filesystem >> as of the time that I mounted it ro. Any subsequent changes on host A >> (which has it mounted rw) are not seem on host B unless I unmount and >> mount again on host B. This seems like a FreeBSD feature and not a >> general scsi feature. > > > By what mechanism do you mount the partitions remote? I'm not very > experienced with this. I'm thinking of a typical network file system or > GEOM gate. I have two servers connected directly to a fiber channel disk array (containing 16 WD Raptor SATA drives in RAID0+1 configuration). Each server sees the same exact luns, so I create the partition and filesystem from host A. I mount it (rw) on host A. Then, if I do a: camcontrol rescan all on host B, I pick up the fiber channel disk and it sees it as da0 (just like on host A). I can then mount it rw or ro on host B. I think using GEOM gate might give a similar situation. Eric -- ------------------------------------------------------------------------ Eric Anderson Sr. Systems Administrator Centaur Technology A lost ounce of gold may be found, a lost moment of time never. ------------------------------------------------------------------------