From owner-freebsd-fs@FreeBSD.ORG Mon Jun 23 20:04:40 2003 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 83A8E37B401 for ; Mon, 23 Jun 2003 20:04:40 -0700 (PDT) Received: from mta04ps.bigpond.com (mta04ps.bigpond.com [144.135.25.158]) by mx1.FreeBSD.org (Postfix) with ESMTP id CE0D243FAF for ; Mon, 23 Jun 2003 20:04:38 -0700 (PDT) (envelope-from areilly@bigpond.net.au) Received: from areilly.bpc-users.org ([144.135.25.72]) by mta04ps.email.bigpond.com (iPlanet Messaging Server 5.2 HotFix 1.14 (built Mar 18 2003)) with SMTP id <0HGY00FWATTIX6@mta04ps.email.bigpond.com> for freebsd-fs@freebsd.org; Tue, 24 Jun 2003 13:03:18 +1000 (EST) Received: from cpe-144-132-191-61.nsw.bigpond.net.au ([144.132.191.61]) by psmam02bpa.bigpond.com(MAM $Name: REL_3_3_2b $ 80/3793867); Tue, 24 Jun 2003 13:03:20 +0000 Received: (qmail 63236 invoked from network); Tue, 24 Jun 2003 03:03:25 +0000 Received: from localhost (HELO ?127.0.0.1?) (andrew@127.0.0.1) by localhost with SMTP; Tue, 24 Jun 2003 03:03:25 +0000 Date: Tue, 24 Jun 2003 13:03:25 +1000 From: Andrew Reilly In-reply-to: To: Mohammad Nayyer Zubair Message-id: <1056423804.48266.54.camel@gurney.reilly.home> MIME-version: 1.0 X-Mailer: Ximian Evolution 1.4.0 Content-type: text/plain Content-transfer-encoding: 7BIT References: cc: freebsd-fs@freebsd.org Subject: Re: ideas about a unioning file system X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 24 Jun 2003 03:04:40 -0000 Hi, On Fri, 2003-06-20 at 08:15, Mohammad Nayyer Zubair wrote: > Has anyone extensively used freebsd unionfs? From a system/network > administrator or from a kernel developer standpoint, what do you like > about it and what you dont like about it? I'm using unionfs thusly: # Device Mountpoint FStype Options Dump Pass# /dev/ad0s1a / ufs rw 0 1 /dev/vinum/mirror /home ufs rw 0 2 /dev/vinum/vinum0 /usr ufs rw,union 0 2 (sorry about the wrappage, cut and pasted from /etc/fstab.) There are other lines in /etc/fstab, of course, but these are the bulk of my workstation's file hierarchy. After years of tiny root partitions that eventually caused grief and breakage because of gradually expanding kernels/modules/cruft-in-etc, this time around I've made root about 500M and put the whole FreeBSD base system in there. So a buildworld/kernel/installworld touches everything in ad0s1a, and nothing else does (except /etc). This leaves the problem of what to do with /usr/ports, /usr/X11R6, /usr/local, /compat@->usr/compat, /tmp@->var/tmp, /var@->usr/var I could have mounted /dev/vinum/vinum0 somewhere like /usr1, and filled /usr with a bunch of symlinks, and I did that for a while. It's messy though, and quite a few things, like ports, bother to find their "true" path, so the /usr1 name leaks into config files and what-not. Ugly. Union mounting seems to be working for me. I do my backups, and it's not a super-heavily used system... Touch wood. > How should a unioning filesystem should behave? What specific features > would you like it to have? It should behave just the way it does: the stuff in /usr that was there before the mount stays there, and gets modified and all, just as it should be. Anything that wasn't in /usr before the mount gets written to the union partition. Reads see both. > Out of the previous efforts at a unioning file system like the Sun's TFS, > 3DFS, Plan 9 and FreeBSD unionfs itself, which fs do you think came close > to an ideal unioning file system? What's wrong with the one that we have? Cheers, -- Andrew Reilly