From mboxrd@z Thu Jan 1 00:00:00 1970 From: Linus Torvalds Subject: Re: what's the current wisdom on git over NFS/CIFS? Date: Thu, 2 Jul 2009 13:58:25 -0700 (PDT) Message-ID: References: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: git@vger.kernel.org To: Sitaram Chamarty X-From: git-owner@vger.kernel.org Thu Jul 02 22:58:37 2009 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 1MMTMY-0003LV-S5 for gcvg-git-2@gmane.org; Thu, 02 Jul 2009 22:58:35 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753858AbZGBU6Z (ORCPT ); Thu, 2 Jul 2009 16:58:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753509AbZGBU6Y (ORCPT ); Thu, 2 Jul 2009 16:58:24 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:60731 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752912AbZGBU6X (ORCPT ); Thu, 2 Jul 2009 16:58:23 -0400 Received: from imap1.linux-foundation.org (imap1.linux-foundation.org [140.211.169.55]) by smtp1.linux-foundation.org (8.14.2/8.13.5/Debian-3ubuntu1.1) with ESMTP id n62KwPEb031643 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Thu, 2 Jul 2009 13:58:26 -0700 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 n62KwPr6021111; Thu, 2 Jul 2009 13:58:25 -0700 X-X-Sender: torvalds@localhost.localdomain In-Reply-To: User-Agent: Alpine 2.01 (LFD 1184 2008-12-16) X-Spam-Status: No, hits=-3.467 required=5 tests=AWL,BAYES_00 X-Spam-Checker-Version: SpamAssassin 3.2.4-osdl_revision__1.47__ X-MIMEDefang-Filter: lf$Revision: 1.188 $ X-Scanned-By: MIMEDefang 2.63 on 140.211.169.13 Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: On Thu, 2 Jul 2009, Sitaram Chamarty wrote: > > A couple of us were beating each other senseless on this > issue over on #git, so I thought I'd ask: is it OK to do > this? Or would there potential be race conditions due to > the lack of proper locking? It should all work fine. We've had a few NFS issues due to oddities with renaming across directories, but modern git avoids the cross-directory renames, and that whole issue only hit some very specific cases anyway. And git doesn't have "proper locking", because it doesn't need it for database ops: git objects are stable. For refs, git should be using the proper NFS-safe "create and atomic rename" ops. You do need to be a bit careful if you do maintenance operations concurrently (I would suggest avoiding doing concurrent "git gc --prune", for example), but any normal git workflow should be fine. There is one big thing to look out for: performance. You may want to add [core] PreloadIndex = true in your .git/config file, especially if you have a high-latency NFS server (but if you have a fast network and a high-end NFS server, you might be better off without it, so do your own testing). Btw, I think we fixed the problem we had with CIFS. That one was a cifs filesystem problem on Linux, but it should be fixed in 2.6.30+ (commit 0f4d634c: "cifs: flush data on any setattr"). If you have an older kernel (or are just uncertain), you can also work around it with [core] fsyncobjectfiles = true which may be a good thing in general (regardless of any cifs issues), but in most cases the performance loss isn't worth it if your filesystem is stable and sane. Linus