On Mon, 23 Jul 2007, Wietse Venema wrote:
> Christopher E. Brown:
> > True MailDir, and the extented Maildir+ are NFS clean.
>
> What happens with non-idempotent requests, such as:
> - client requests link(tmp, new)
> - server reply is lost
> - server crashes and loses the request ID cache.
> - client times out
> - client requests link(tmp, new) (retransmission)
> - server replies with error (file exists)
Maybe I am missing somthing here, please fill me in if I am. I can think
of corner cases where this could cause duplicate messages.
It is not ideal, but better than losing the message. Also, while this
would seem to me more likely to happen over NFS (timing less critical,
larger window), I would think that a system crash at the wrong moment
could trigger the same issue on most any filesystem.
The only way around this would require a stateful filesystem that the
application was fully aware of and that the mailspool format/procedures
were designed to work with.
|
