>The online mirroring the new stuff supports (when its done) and which at
>least vaguely worked in the original demo patches with omirrd seems to do
>remarkably well. It has exactly zero coherency features although you could
>extend that I suspect but that will be hard.
I get the impression that the OMIRR system is not designed to support
such demanding applications as the /var/spool/mail directory for a busy
mail server. Maybe at some future time it will do so, but my understanding
is that it is designed to copy changes across multiple machines as soon as
is conveniant. So if 2 processes on different machines started actively
writing the same file then the results probably would not be much better
than if the file was on a single NFS file server.
So the issue is not merely that they haven't implemented these features,
but that they have decided to design it to meet different objectives.
The /var/spool/mail case is the only example I can think of which won't
work very well with OMIRR. User home directories (assuming that the user
doesn't log into 2 machines and try writing the same file - anyone who has
used NFS home directories won't do that), Qmail maildir mail storage,
application files (for a file server) and most other types of data should
work well with it.
Russell Coker