On 5 May 2015, at 1:57pm, Keith Medcalf <kmedcalf at dessus.com> wrote:
> There is no difference between a file opened over the network and one opened > locally, except that in the network open case the network filesystem does not > maintain consistency between the client view of the file and the server view > of that same file, because doing so takes time and the network filesystem > designer decided to trade off in favour of speed over consistency, usually > without provision of a knob to change this decision. Keith, I think you're ignoring the fact that when opening a file across a network the file system knows it's operating across the network and does not make the assumption that its cache is valid. If things operated the way you describe almost all shared access operations would lead to corruption. Operations when opening a file across a network are slower because the NFS has to check whether the file has been updated since its local copy was cached. The various teams which develop network file systems like NFS SMB and AFP all worried about these things and got them right. Individual clients won't write out-of-date caches back to a centrally held file unless you've explicitly turned off the network-savvy routines. Simon.
