Dovecot 2.2.16: disappearing messages, mismatched summaries, duplicated messages, excessive full re-downloads

[Joseph Tam]

David Gessel writes:

> As far as anyone has been able to determine, all artifacts are
> resolved.  I believe it is fair to say "SOLVED." As I often start
> trying to solve problems by searching the list archives, I'll append my
> description of the artifacts as googlebait to the bottom of this
> message.

To say that disabling the use of index files solved your problems is akin
to saying amputating your foot solved your bunion problems.  Ordinarily,
indices ought to be a benefit -- it will help with I/O bottlenecks when
mailboxes or number of users get huge.

I can't tell from your list of problems whether they are the result of
one or many causes, but fixing the index consistency problem would go
a long way toward clearing up most of your problems.

If INDEX=MEMORY is working for you and you don't see performance
degradation, there's no harm in using it, but in my opinion, it may
benefit you in the future to get to the bottom of the indexing problem
rather than to lop it off altogether.

> I am curious if setting INDEX=MEMORY "disables the index completely" as
> per http://wiki2.dovecot.org/MailLocation: "If you really want to, you
> can also disable the index files completely by appending
> :INDEX=MEMORY." Or if there are index files in memory as one might
> assume taking the directive literally, and if so, if these are
> functionally equivalent to, say, Courier IMAP's caching model.

The latter I believe.  The important words in the wiki sentence is "index
files", not "indexing".  Dovecot is still indexing, exept that it builds
it from scratch each and every time a worker process accesses a mailbox,
so incurs a fixed overhead that cannot be used for the next session.

Joseph Tam <jtam.home at gmail.com>