From owner-freebsd-geom@FreeBSD.ORG Thu Jul 10 23:42:35 2008 Return-Path: Delivered-To: freebsd-geom@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 293C61065676 for ; Thu, 10 Jul 2008 23:42:35 +0000 (UTC) (envelope-from mark@legios.org) Received: from bade.legios.org (ppp198-172.static.internode.on.net [59.167.198.172]) by mx1.freebsd.org (Postfix) with ESMTP id D623E8FC1D for ; Thu, 10 Jul 2008 23:42:34 +0000 (UTC) (envelope-from mark@legios.org) Received: from localhost (unknown [192.168.0.17]) by bade.legios.org (Postfix) with ESMTP id 0213A1AD735 for ; Fri, 11 Jul 2008 09:42:13 +1000 (EST) X-Virus-Scanned: amavisd-new at legios.org Received: from bade.legios.org ([192.168.0.17]) by localhost (legios.org [192.168.0.17]) (amavisd-new, port 10024) with ESMTP id xGbr9iRFVINI for ; Fri, 11 Jul 2008 09:41:58 +1000 (EST) Received: from [192.168.0.200] (unknown [192.168.0.200]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by bade.legios.org (Postfix) with ESMTP id 2E9AD1AD72C for ; Fri, 11 Jul 2008 09:41:58 +1000 (EST) From: Mark Gladman To: freebsd-geom@freebsd.org Date: Fri, 11 Jul 2008 09:40:05 +1000 User-Agent: KMail/1.9.7 References: <482257ad0807100541s2d2c3d1eo6cd57c3a1bc338d1@mail.gmail.com> <482257ad0807100655u1a5c660awfad05564e40e9a95@mail.gmail.com> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200807110940.05862.mark@legios.org> Subject: Re: Can GEOM be used to intercept the I/o calls to an existing mounted device? X-BeenThere: freebsd-geom@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: GEOM-specific discussions and implementations List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 10 Jul 2008 23:42:35 -0000 On Friday 11 July 2008 05:19:35 Ivan Voras wrote: > Tapan Chaudhari wrote: > > Can't I do it on the fly while the device is already mounted? I just want > > that all the calls going to the device "/dev/md0s1" first come to me and > > then it goes to the original device. In short intercepting the i/o calls. > > Is there some way I can achieve this? > > It would be very nice if GEOM could do this, since it would then > trivially allow things like data replication, log/rollback, etc. but it > doesn't work like that. In short, no, you cannot listen to IO between > providers. > > (not that it isn't possible to do at all, it just isn't implemented). Whoops - I was *totally* focussing on the wrong part of his question... (It was late, that's my excuse. :)