From mboxrd@z Thu Jan 1 00:00:00 1970 From: Linus Torvalds Subject: Re: git guidance Date: Thu, 29 Nov 2007 08:19:58 -0800 (PST) Message-ID: References: <20071129105220.v40i22q4gw4cgoso@intranet.digizenstudio.com> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: Al Boldi , linux-kernel@vger.kernel.org, git@vger.kernel.org To: Jing Xue X-From: git-owner@vger.kernel.org Thu Nov 29 17:21:34 2007 Return-path: Envelope-to: gcvg-git-2@gmane.org Received: from vger.kernel.org ([209.132.176.167]) by lo.gmane.org with esmtp (Exim 4.50) id 1Ixm8p-0004RF-1a for gcvg-git-2@gmane.org; Thu, 29 Nov 2007 17:21:31 +0100 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759050AbXK2QUc (ORCPT ); Thu, 29 Nov 2007 11:20:32 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932183AbXK2QUc (ORCPT ); Thu, 29 Nov 2007 11:20:32 -0500 Received: from smtp2.linux-foundation.org ([207.189.120.14]:57709 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758976AbXK2QUa (ORCPT ); Thu, 29 Nov 2007 11:20:30 -0500 Received: from imap1.linux-foundation.org (imap1.linux-foundation.org [207.189.120.55]) by smtp2.linux-foundation.org (8.13.5.20060308/8.13.5/Debian-3ubuntu1.1) with ESMTP id lATGJwh8032212 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Thu, 29 Nov 2007 08:19:59 -0800 Received: from localhost (localhost [127.0.0.1]) by imap1.linux-foundation.org (8.13.5.20060308/8.13.5/Debian-3ubuntu1.1) with ESMTP id lATGJwuv028307; Thu, 29 Nov 2007 08:19:58 -0800 In-Reply-To: <20071129105220.v40i22q4gw4cgoso@intranet.digizenstudio.com> X-Spam-Status: No, hits=-2.688 required=5 tests=AWL,BAYES_00,TW_VC X-Spam-Checker-Version: SpamAssassin 3.1.0-osdl_revision__1.47__ X-MIMEDefang-Filter: lf$Revision: 1.188 $ X-Scanned-By: MIMEDefang 2.53 on 207.189.120.14 Sender: git-owner@vger.kernel.org Precedence: bulk X-Mailing-List: git@vger.kernel.org Archived-At: On Thu, 29 Nov 2007, Jing Xue wrote: > > By the way, the only SCM I have worked with that tries to mount its > repository (or a view on top of it) as a file system is ClearCase with > its dynamic views. And, between the buggy file system implementation, > the intrusion on workflow, and the lack of scalability, at least in > the organization I worked for, it turned out to be a horrible, > horrible, horrible idea. Doing a read-only mount setup tends to be pretty easy, but it's largely pointless except for specialty uses. Ie it's obviously not useful for actual *development*, but it can be useful for some other cases. For example, a read-only revctrl filesystem can be a _very_ useful thing for test-farms, where you may have hundreds of clients that run tests on possibly different versions at the same time. In situations like that, the read-only mount can actually often be done as a user-space NFS server on some machine. The advantage is that you don't need to export close to infinite amounts of versions from a "real" filesystem, or make the clients have their own copies. And if you do it as a user-space NFS server (or samba, for that matter), it's even portable, unlike many other approaches. The read-only part also makes 99% of all the complexity go away, and it turns out to be a fairly easy exercise to do. So I don't think the filesystem approach is _wrong_ per se. But yes, doing it read-write is almost invariably a big mistake. On operatign systems that support a "union mount" approach, it's likely much better to have a read-only revctl thing, and then over-mount a regular filesystem on top of it. Trying to make it read-write from the revctl engine standpoint is almost certainly totally insane. Linus