Thanks Jan. A very detailed reply - the kind I was looking for. >I believe that in Linux 2.6, there is a concept of a stackable >filesystem. It should be somehow possible to mount a filesystem over >another and the filesystem mounted on top should be able to access the >filesystem below, provided it's designed to do that. > >In other words, I think you should NOT do it in VFS, but do it as >a special filesystem. This filesystem would implement all the methods of >dentry, inode and file and in these methods, redispatch to another FS >driver (by doing manual path_walk and calling respective >inode/dentry/file objects). This idea seems good. I guess I will work towards this. > >It's also possible to use the coda interface to kernel and implement >your filesystem in userland. There are libraries -- fuse and lufs -- >that will help you with that. > >After all, when I think of it, coda itself is quite probably a good >solution for you, without writing a single line of code. Yes, Coda would've worked fine except that it works in a client-server mode. Unfortunately, with a NetApp I can't install any programs on it. >> >> Does this sound like a proper and feasible design? > >No. That's error-prone and dirty. Will keep that in mind. >* intermezzo: This is similar to coda in features, but lighter in > implementation (it actualy uses normal http server for serving file > content). It is younger and thus a bit less tested. It is also > supported on less other OSes. Intermezzo works in a similar manner as coda. Moreover, it polls the files for recording changes - something I wish to avoid given the large number of files. As I said earlier, in my testing rsync was slow not because the volume of change of big but because it would've have to go through thousands of files. >* afs: This filesystem predates, and inspires, coda. It has the client > fully in kernel. It does not support disconnected operation. On the > other hand since it caches blocks and not whole files, it works better > real-time. It's drawback is, that the driver is not that stable. It's > not that bad, however. We have it in a computer lab and it works just > well (NFS used to be much worse), even across different systems > (linux, solaris, irix and windows). It is not shipped with kernel. The mail servers serve multiple customers. Can't put unstable code in there :) Thanks again, Siddhartha -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
