From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Xin Zhao" Subject: Re: how do versioning filesystems take snapshot of opened files? Date: Tue, 3 Jul 2007 12:31:49 -0400 Message-ID: <4ae3c140707030931u14119061m5d5dc69834292847@mail.gmail.com> References: <20070703090946.49e6062f@think.oraclecorp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: "Chris Mason" , linux-fsdevel To: "Bryan Henderson" Return-path: Received: from nz-out-0506.google.com ([64.233.162.233]:54562 "EHLO nz-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753738AbXGCQbu (ORCPT ); Tue, 3 Jul 2007 12:31:50 -0400 Received: by nz-out-0506.google.com with SMTP id s18so1272955nze for ; Tue, 03 Jul 2007 09:31:50 -0700 (PDT) In-Reply-To: Content-Disposition: inline Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org That's a good point! But this sounds hopeless to take a real consistent snapshot from app perspective unless you shutdown the computer. Right? Thanks. On 7/3/07, Bryan Henderson wrote: > > Consistent state means many different things. > > And, significantly, open/close has nothing to do with any of them > (assuming we're talking about the system calls). open/close does not > identify a transaction; a program may open and close a file multiple times > the course of making a "single" update. Also, data and metadata updates > remain buffered at the kernel level after a close. And don't forget that > a single update may span multiple files. > > -- > Bryan Henderson IBM Almaden Research Center > San Jose CA Filesystems > >