On Mon, 4 May 2015 02:05:54 +0100 Simon Slavin <slavins at bigfraud.org> wrote:
> On 4 May 2015, at 1:30am, James K. Lowden <jklowden at schemamania.org> > wrote: > > > That is the way most remote filesystems are designed and implemented > > and documented. Cf. http://www.ietf.org/rfc/rfc1813.txt: > > > > 4.11 Caching policies > > > > The NFS version 3 protocol does not define a policy for > > caching on the client or server. In particular, there is no > > support for strict cache consistency between a client and > > server, nor between different clients. See [Kazar] for a > > discussion of the issues of cache synchronization and > > mechanisms in several distributed file systems. > > > > If you can find documentation for cache semantics for CIFS, I'd be > > interested to see it. > > In contrast to NFS both SMB and AFP are designed to support networks > properly, with caches only on the computer which hosts the file and > locking correctly implemented. Are you saying that SMB clients have no filebuffer cache? Or that it exists, but is reliably invalidated by writes from other clients? >From what I remember from configuring Samba, SMB is 1) very complicated (lots of versions and knobs) and 2) undocumented in numerous ways. The prototocol is better documented these days, thanks to the EU, but I've never seen anything resembling semantic guarantees. So I'm skeptical of any assertion that it Just Works, even subject to the constraints you mention. --jkl
