Date: Fri, 23 Jul 1999 06:45:35 -0400 (EDT) From: Robert Watson <robert@cyrus.watson.org> To: Nik Clayton <nik@nothing-going-on.demon.co.uk> Cc: hackers@freebsd.org Subject: Re: InterMezzo: Project for kernel/FS hackers Message-ID: <Pine.BSF.3.96.990723064029.3102G-100000@fledge.watson.org> In-Reply-To: <19990722211946.A31641@catkin.nothing-going-on.org>
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On Thu, 22 Jul 1999, Nik Clayton wrote: > Hi chaps, > > Not entirely sure which list to post this too, so I figured that -hackers > was probably most appropriate. > > Has anyone had the chance to look at InterMezzo, website at > > http://www.inter-mezzo.org/ > > It's main claim to fame is that it allows disconnected operation. For > example, you could have a server export a home directory to a laptop, > then unplug the laptop from the network, and go and edit/add/delete files > from the home directory stored on the laptop. When the laptop is then > plugged back in to the network, the filesystem automatically (as far > as possible) integrates the changes). > > Coda (which already has a FreeBSD port) also does this, as well as a few > other things. However, Coda is much more heavyweight than InterMezzo, > and therefore easier to understand -- in particular, Coda seems to have > (according to one of the Coda developers) a marked preference for > exporting whole filesystems, InterMezzo allows you to export individual > directory trees. > > Anyway, if any aspiring kernel hackers are looking for a project, that > might be a fun one. The only implementation at the moment is for Linux. > > Cheers, What I'd actually like to see is a port of Inter-mezzo to use the Arla kernel module, which is far more portable/etc, and is also under a BSD license (both Coda and Inter-mezzo are under GPL). I have worked a fair amount with the Arla module to build some user-land file system code, but have no experience with Inter-mezzo. I do have experience with the Coda module, and can say they are quite similar (although the Arla code seems more thread-aware and RPC-like). I have hopes that we can integrate the Arla module into the base FreeBSD distribution, as OpenBSD has done, as it is looking quite stable and makes userfs programming a lot easier. OpenBSD has also integrated the Arla userland support for AFS, which might also be nice to integrate into the base distribution at some point, but is perhaps less useful than integrating the kernel module as the userland code can easily be made a package. As to your comments on Coda: Coda requires custom storage on the server, and cannot export a regular file system. I'm not sure how Inter-Mezzo handles these things: they might require the storage of log/version information on the server somewhere to aid in reintegrating disconnected changes, but again I don't know all that much about it. What I do know is that Coda desperately requires simplification and a fresh code base, so it seems like a step forwards. :-) Robert N M Watson robert@fledge.watson.org http://www.watson.org/~robert/ PGP key fingerprint: AF B5 5F FF A6 4A 79 37 ED 5F 55 E9 58 04 6A B1 TIS Labs at Network Associates, Computing Laboratory at Cambridge University Safeport Network Services To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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