(Illustration by Gaich Muramatsu)
On Fri, 3 Apr 1998, David C. Steere wrote: > Satya'll probably crucify me for this... > > Another way to solve the same problem is to use the ficus approach: the > things you call servers in your diagram are really clients (use the coda > client protocols to keep consistent), and export their files to other > clients. Ficus used NFS to export stuff from their client/server to the > real clients, we could do that or hack the coda servers to export files > from their filesystems and not from the special coda partion as is > currently the case. (The other drawback of their approach is that they do > not distinguish between clients and servers, which makes it hard to do > administration). > > I posted this question a while back, has anyone had time to consider it? > (Having Coda servers export local files, nfs files, cdrom files, etc). There has been discussion of exporting read-only file systems (such as CDROMs) since it would be easy to dynamically create version vectors (there are few if any changes :). One idea I have been interested in is a tertiary storage manager -- i.e., a large repository of mechanically accessible tapes, etc, and Vice keeping a cache of those files on its hard disk. When there is a cache miss, it pulls the file out of tertiary storage and makes it available to the Venus requesting it, either transparently, or depending on latency with a 2-step process where the request is acknowledged but postponed, and then later provided. Dealing with relication here would be an interesting challenge. My concern with NFS-exporting Coda file systems is the largely different semantics of authentication, authorization, not to mention vice cache misses or running into a conflict that requires user intervention for resolution. I suppose with an entirely user-land nfsd, this would be possible. I know that this is used with AFS with varying degrees of success. In the long run, however, it would be nice to see support in Coda for doing this directly -- I suspect that the scenarios described in my previous email are far from uncommon now, and with the increase in use of mobile computing in various forms, they will become no less common. Robert N Watson ---- Carnegie Mellon University http://www.cmu.edu/ Trusted Information Systems http://www.tis.com/ SafePort Network Services http://www.safeport.com/ robert@fledge.watson.org http://www.watson.org/~robert/Received on 1998-04-03 13:46:34