Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 18 Apr 2002 11:06:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 18 Apr 2002 11:05:59 -0400 Received: from borg.org ([208.218.135.231]:9868 "HELO borg.org") by vger.kernel.org with SMTP id ; Thu, 18 Apr 2002 11:05:58 -0400 Date: Thu, 18 Apr 2002 11:05:58 -0400 From: Kent Borg To: linux-kernel@vger.kernel.org Subject: Versioning File Systems? Message-ID: <20020418110558.A16135@borg.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org I just read an article mentioned on Slashdot, . It is a fascinating short summary of the history of hard disks (they still use the same fundamental design as the very first one) and an update on current technology (disks are no longer aluminum). It also looks at today's 120 gigabyte disk and muses over the question of how we might ever put an imagined 120 terabyte disk to use. And the got me thinking various thoughts, one turns into a question for this list: It there any work going on to make a versioning file system? I remember in VMS that I could accumulate "myfile.txt;1", "myfilw.txt;2", etc., until the local admin got pissed at me for using up all the disk space with my several megabytes of redundant files. It is time for Linux to start figuring out ways to use all the disk space that is on the horizon! In a few weeks the sweet spot will be to buy a pair of 80 GB disks. Disks are outpacing even Red Hat's "everything" install. Seriously, I have a server in the basement with a pair of 60 GB RAID 1 disks the protect me against likely hardware failure, but they don't protect me against: "# rm rf /*". They don't even let me easily back out a bad RPM from Red Hat. I guess I am suggesting the (more constructive) discussions over desirable Bitkeeper and CVS features consider what it would mean for a filesystem to absorb some of the key underlying features of each. As a first crack, I am imagining a file system that records every (or nearly every) change to every file with time stamps and sequence numbering. I don't know what all the primitives would be. It obviously seems much of making sense of it all would have to happen in userland. Making this too powerful almost brings up some science fiction problems of time travel through parallel universes, but I think it could be kept grounded by looking at it as a powerful version of existing backup systems: they don't have such problems because they are too cumbersome for them to arise very often. -kb, the Kent who thinks his journaled filesystem on redundant disks next needs a better memory. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/