From owner-freebsd-geom@FreeBSD.ORG Sun Mar 22 13:02:37 2009 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 7676A1065674; Sun, 22 Mar 2009 13:02:37 +0000 (UTC) (envelope-from ivoras@gmail.com) Received: from mail-fx0-f167.google.com (mail-fx0-f167.google.com [209.85.220.167]) by mx1.freebsd.org (Postfix) with ESMTP id B50428FC14; Sun, 22 Mar 2009 13:02:36 +0000 (UTC) (envelope-from ivoras@gmail.com) Received: by fxm11 with SMTP id 11so1350592fxm.43 for ; Sun, 22 Mar 2009 06:02:35 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <45710.1237709582@critter.freebsd.dk> References: <45710.1237709582@critter.freebsd.dk> Date: Sun, 22 Mar 2009 14:02:20 +0100 Received: by 10.204.31.101 with SMTP id x37mr2097984bkc.4.1237726955458; Sun, 22 Mar 2009 06:02:35 -0700 (PDT) Message-ID: <9bbcef730903220602q736b96dflab447e2d6d996754@mail.gmail.com> From: Ivan Voras To: Poul-Henning Kamp Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Cc: Pawel Jakub Dawidek , luigi@freebsd.org, Luigi Rizzo , freebsd-geom@freebsd.org Subject: Re: disk scheduling (was: Re: RFC: adding 'proxy' nodes to provider ports (with patch)) 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: Sun, 22 Mar 2009 13:02:37 -0000 2009/3/22 Poul-Henning Kamp : > In message ,= Luigi > =C2=A0Rizzo writes: > >>The thread was meant to be on inserting transparent nodes in GEOM. >> >>Scheduling was just an example on where the problem came out, > > Scheduling is the *only* application I have seen mentioned for > this special case geom construct ? I've joined this thread because once upon a time I was working on what has grown into gjournal, and one aspect of the original project was a logging "safety net" mode. The idea was to insert this class (or whatever) just before a file system consumer then do risky things with the file system metadata (like fsck-ing a badly damaged file system), with the option of commiting it or rolling it back. It has even grown into another SoC project. I see now it doesn't comply with my idea of a "lightweight" proxy (the first item, about 1:1 mappings) - so proxies look more and more like they should be classes. Also, gcache looks like a candidate.