Director+NFS Experiences

[Timo Sirainen]

On 24 Feb 2017, at 0.08, Mark Moseley <moseleymark at gmail.com> wrote:
> 
> As someone who is about to begin the process of moving from maildir to
> mdbox on NFS (and therefore just about to start the 'director-ization' of
> everything) for ~6.5m mailboxes, I'm curious if anyone can share any
> experiences with it. The list is surprisingly quiet about this subject, and
> articles on google are mainly just about setting director up. I've yet to
> stumble across an article about someone's experiences with it.
> 
> * How big of a director cluster do you use? I'm going to have millions of
> mailboxes behind 10 directors.

I wouldn't use more than 10.

> I'm guessing that's plenty. It's actually split over two datacenters.

Two datacenters in the same director ring? This is dangerous. if there's a network connectivity problem between them, they split into two separate rings and start redirecting users to different backends.

> * Do you have consistent hashing turned on? I can't think of any reason not
> to have it turned on, but who knows

Definitely turn it on. The setting only exists because of backwards compatibility and will be removed at some point.