[Dovecot] (new) director issues in 2.1.10

[Kelsey Cummings]

Timo - I upgraded to 2.1.10 on our director servers two nights ago and 
apart from errors associated with the directors processes restarting 
everything looked great for ~24 hours until I failed our the real 
servers last night to update the nfs mount options for the spools.

I followed the suggested procedure for each backend server, just run on 
one of the directors, which seemed to work as expected.

doveadm director add x.x.x.x 0
doveadm director flush x.x.x.x

The following errors on the directors that started after this went 
unnoticed until this AM.

director: User bb host lookup failed: Timeout - queued for 30 secs (Ring 
synced for 36 secs)
director: User cc host lookup failed: Timeout - queued for 48 secs (Ring 
synced for 66 secs, user refreshed 12 secs ago)
director: User dd host lookup failed: Timeout - queued for 124 secs 
(Ring synced for 119 secs, weak user, user refreshed 155 secs ago)
director: User ee host lookup failed: Timeout - queued for 79 secs (Ring 
synced for 119 secs, weak user, user refreshed 113 secs ago)
...
User ff host lookup failed: Timeout - queued for 30 secs (Ring synced 
for 7427 secs, weak user, user refreshed 620 secs ago)


This continued, combined with occasional login timeouts (as reported by 
some internal imap clients.)  The login delays/timeouts got bad enough 
that our load balancers dropped both the servers while I was 
investigating. They seem to be okay after being restarted.


-K