On 23.1.2012, at 21.13, Mark Moseley wrote: > In playing with dovecot director, a couple of things came up, one > related to the other: > > 1) Is there an effective maximum of directors that shouldn't be > exceeded? That is, even if technically possible, that I shouldn't go > over?
There's no definite number, but each director adds some extra traffic to network and sometimes extra latency to lookups. So you should have only as many as you need. > Since we're 100% NFS, we've scaled servers horizontally quite a > bit. At this point, we've got servers operating as MTAs, servers doing > IMAP/POP directly, and servers separately doing IMAP/POP as webmail > backends. Works just dandy for our existing setup. But to director-ize > all of them, I'm looking at a director ring of maybe 75-85 servers, > which is a bit unnerving, since I don't know if the ring will be able > to keep up. Is there a scale where it'll bog down? That's definitely too many directors. So far the largest installation I know of has 4 directors. Another one will maybe have 6-10 to handle 2Gbps traffic. > 2) If it is too big, is there any way, that I might be missing, to use > remote directors? It looks as if directors have to live locally on the > same box as the proxy. For my MTAs, where they're not customer-facing, > I'm much less worried about the latency it'd introduce. Likewise with > my webmail servers, the extra latency would probably be trivial > compared to the rest of the request--but then again, might not. But > for direct IMAP, the latency likely be more noticeable. So ideally I'd > be able to make my IMAP servers (well, the frontside of the proxy, > that is) be the director pool, while leaving my MTAs to talk to the > director remotely, and possibly my webmail servers remote too. Is that > a remote possibility? I guess that could be a possibility, but .. Why do you need so many proxies at all? Couldn't all of your traffic go through just a few dedicated proxy/director servers?
