[Dovecot] quick question

[David Halik]

On 01/22/2010 12:16 PM, Timo Sirainen wrote:
> Looking at the problems with people using NFS it's pretty clear that this
> solution just isn't going to work properly.
>    

Actually, considering the amount of people and servers we're throwing at 
it, I think that it's dealing with it pretty well. I'm sure there are 
always more tweaks and enhancements that can be done, but look at how 
much better 1.2 is over 1.0 releases. it's definitely not "broken," just 
maybe not quite production ready as it could be. Honestly, at this point 
my users are very happy with the speed increase and as long as their 
imap process isn't dying they don't seem to notice the behind the scenes 
corruption because of the self healing code.

> But then again, Dovecot is the only (free) IMAP server that even
> attempts to support this kind of behavior. Or sure, Courier does too,
> but disabling index files on Dovecot should get the same stability.
>    

By the way, I didn't want to give the impression that we were unhappy 
with the product, rather I think what you've accomplished with dovecot 
is great even by non-free enterprise standards, not to mention the level 
of support you've given us has been excellent and I appreciate it 
greatly. It was a clear choice for us over courier once NFS support 
became a reality. Loads on the exact same hardware dropped from an 
average of 5 to 0.5, quite amazing, not to mention the speed benefit of 
the indexes. Our users with extremely large Maildir's were very satisfied.


> I see only two proper solutions:
>
> 1) Change your architecture so that all mail accesses to a specific user
> go through a single server. Install Dovecot proxy so all IMAP/POP3
> connections go through it to the correct server.
>    

We've discussed this internally and are still considering layer7 
username balancing as a possibility, but I haven't worked too much on 
the specifics yet. We've only been running for two months on dovecot, so 
we wanted to give it some burn in time and see how things progressed. 
Now that the core dumps are fixed, I think we might be able to live with 
the corruption for awhile. The only user visible issue that I was aware 
of was the the users' mailbox disappearing when the processes died, but 
since that's not happening any more I'll have to see if anyone notices 
the corruption.

Thanks for all the feedback. I'm going over some of the ideas you 
suggested and we'll be thinking about long term solutions.

-- 
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David Halik
System Administrator
OIT-CSS Rutgers University
dhalik at jla.rutgers.edu
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