On Wed, 2006-05-24 at 16:45 -0400, John T. Kohl wrote: > > If you have multiple processes talking to different server replicas, can > you then get cases where the processes aren't sharing the same files given > the same name? Sounds like it to me. > Process "A" looks up /mount/a/b/c/file.c (using server 1) opens it and > starts working on it. It then sits around doing nothing for a while. > > Process "B" cd's to /mount/a/b, gets a timeout, fails over to server 2, > and then looks up "c/file.c" which will be referencing the object on > server 2 ? Yup. > A & B then try locking to cooperate... Yup. To get good locking semantics, you'll probably need a distributed filesystem like GFS or Lustre. > Are replicas only useful for read-only copies? If they're read-only, do > locks even make sense? Yes, they can - imagine a software system that wants to make sure only one process is accessing some data at a time. The lock might be in one filesystem, but the data might be in another. Or you might be reading from a device that has really expensive seeks (a DVD comes to mind), so you want to be sure that only one thing is reading from it at a time. There are other possible scenarios I imagine, but many folks may be able to live without any of them. :) - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
