I'm sorry Timo, I must be dense... ;)
I'm not sure if I'll change default settings. Maybe I should set mmap_disable=yes at least. But fsync_disable=yes means only that Dovecot doesn't do any fsync() calls, which means that if the computer crashes at that point,
Computer, meaning the dovecot server? Or the Client?
Dovecot could have lied to the client that "OK, your saved message is safe" while in reality it isn't. So it'll default to no, but if you don't care about such problems that much you can enable it..
Sounds like you meant the server/dovecot, since if the Client crashed *before* the operation was complete,. it could not have gotten an "OK, your saved message is safe". No, I wouldn't be worried about that small of a chance - my server has never crashed (Charles runs to knock a hole in a 4x4 block of wood), so, I'd definitely be willing to risk that tiny chance of the server crashing at just the wrong time, to reap the speed benefits you described during normal operations.
I think most people think maildir is faster only because all other mbox readers are so horribly slow.
By reader, I'm assuming you mean server? Or do you actually mean that the mail Client can have such a huge impact on the speed when talking to an IMAP server that uses mbox on the backend?
Also maildir's reliability isn't just because of that "only one message getting corrupted", but it's that once the message has been written, there's no way for it to get corrupted unless the filesystem breaks. With mbox the data is constantly being moved around and it can break both because of software and because computer crashes while moving the data around.
Makes perfect sense. Thanks for taking the time to explain things that must seem painfully obvious to you... :)
--
Best regards,
Charles