>>>>> "pw" == Patrick Welche <prlw1%cam.ac.uk@localhost> writes: pw> Idle question: is there anything coda can do in theory which pw> nfs4 can't? I have never used AFS/Coda but aren't they very different in performance from NFS? Everyone focuses on the nice-soudning aspects of cacheing, but for example, when you open the file, don't AFS/Coda copy the whole thing into the ``cache'' filesystem which is something like FFS, and then map all file access into that FFS? Then copy back changes when (and only when!) you close the file? or am I wrong? If that's the case, using AFS or Coda would work well for reading email or maintaining a tree of .c files, but would ~ not work at all for an .avi collection, a large database, or a VMware/VirtualBox disk image store where the unpathological case requires not transferring the entire file over the network. like, AFS/Coda would just crack and break under this workload, would it not? It is not really a NAS at all, just a backup/collaboration tool. It's hard to get a straight answer so maybe I've got it all wrong. nfs4, fwiw, is not really different from nfsv3. It's supposed to perform better, but often has lots of bugs some of which make it perform worse, or not keep working across a server reboot like it's supposed to. It's supposed to come with this new mess of ACL's, but they are inspired by Windows ACL's so it's like smb.conf and no one really udnerstands them, often break things because solaris likes to ``fabricate'' ACL's and clients support them only partially. There is talk about support for server replication and client failover, but it does not exist yet, not even in the solaris client---only the ``mirror mounts'' thing is working which is just an excuse to avoid using the automounter. Many years after its release its support is pretty rare---even under solaris I cannot get it to mount '/' over nfsv4---keeps coming up as v3 but then you can have it mount /usr over top of it as nfsv4,...so...job is not really finished...but no one is in much of a hurry so no worries. IMHO nfsv4 is more like the inevitable future than the revolution AFS and Coda meant to be. pNFS is something different and actually claims new features: split data/metadata for storing big files like video, database, disk image in clusters. so the true relevant nfsv4 changes were probably laying the path to pNFS. but i don't think pNFS exists yet.
Description: PGP signature