Re: [Exim] Mail storage formats/ POP/IMAP/webmail daemon/etc…

On Sun, 1 Apr 2001, Dave C. wrote:

> > > Ok, but according to exim's doc, MBX locking doesnt work over NFS..
> > >
> > > Argh.. is there no format that doesnt have some major design flaw?!
> >
> > Who said it was a design flaw? Many consider NFS flawed (design or
> > implementation) because of locking issues.
> >
> > maildir is ok on NFS, as long as you're ok with the weaknesses of
> > maildir.
>
> I dont want the weaknesses of either model.

Tough. Each storage method has a weakness(es). Choose your poison.
There is never going to be a perfect system.

> > > I need to support a mixed environment - POP, IMAP, webmail.. I need to
> > > be able to distribute load over multiple servers - which unless someone
> > > has a better idea, means NFS.. I need speed and reliability. So far
> > > nothing seems to fit that bill.
> >
> > I don't understand how NFS will help you distribute load, because
> > everything leads back to the NFS server holding the mailbox.
> >
>
> Ok, you have 50,000 users popping their mailboxes, how do you distribute
> this to multiple servers?

Well, first of all 50,000 users is well wihin the limits of a
modest server. Second, if you distribute "the load" over multiple
servers, but put all the mailboxes on a single backend NFS server, how
have you really distributed the load? The file server is still doing most
of the work, and your front-end POP servers are doing almost nothing other
than copying data.


Tom