In our experience. A ring with more of 4 servers is bad, we have sync problems everyone. Using 4 or less works perfect.
Em 24 de fev de 2017 4:30 PM, "Mark Moseley" <moseleym...@gmail.com> escreveu: > > > > On Thu, Feb 23, 2017 at 3:15 PM, Timo Sirainen <t...@iki.fi> wrote: > > > >> On 24 Feb 2017, at 0.08, Mark Moseley <moseleym...@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. > >> > >> > > Cool > > > > > > > >> > 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. > >> > > > > I was unclear. The two director rings are unrelated and won't ever need > to > > talk to each other. I only mentioned the two rings to point out that all > > 6.5m mailboxes weren't behind one ring, but rather split between two > > > > > > > >> > >> > * 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. > >> > >> > > Out of curiosity (and possibly extremely naive), unless you've moved a > > mailbox via 'doveadm director', if someone is pointed to a box via > > consistent hashing, why would the directors need to share that mailbox > > mapping? Again, assuming they're not moved (I'm also assuming that the > > mailbox would always, by default, hash to the same value in the > consistent > > hash), isn't their hashing all that's needed to get to the right backend? > > I.e. "I know what the mailbox hashes to, and I know what backend that > hash > > points at, so I'm done", in which case, no need to communicate to the > other > > directors. I could see that if you moved someone, it *would* need to > > communicate that mapping. Then the only maps traded by directors would be > > the consistent hash boundaries *plus* any "moved" mailboxes. Again, just > > curious. > > > > > Timo, > Incidentally, on that error I posted: > > Feb 12 06:25:03 director: Warning: director(10.1.20.3:9090/left): Host > 10.1.17.3 is being updated before previous update had finished (up -> down) > - setting to state=down vhosts=0 > Feb 12 06:25:03 director: Warning: director(10.1.20.3:9090/left): Host > 10.1.17.3 is being updated before previous update had finished (down -> up) > - setting to state=up vhosts=0 > > any idea what would cause that? Is my guess that multiple directors tried > to update the status simultaneously correct? >
