[Dovecot] new configure-option --disable-index

[Marcus Rueckert]

On 2006-01-13 18:04:15 +0100, Marten Lehmann wrote:
> I experimented with dovecot the whole evening yesterday and the 
> mailserver worked fine since there haven't been that much users 
> connecting to it. I'm using dovecot 1.0.alpha5 as pop3 and pop3s server. 
> The maildirs are mounted through NFS and since there is no nfslockd 
> running I disabled mmap in the config and told dovecot to use dotlock. 
> Also I experienced, that dovecot was much faster when using one 
> login-process per connection instead of sharing them throughout several 
> connections. Sharings seems to be a greater performance problem 
> (bottleneck) than additional fork()s.
> 
> However, under normal load at business time the server load increased to 
> a value that made it impossible to download emails without timeouts, so 
> we switched back to tcpserver/qmail-pop3d for pop3 and only kept dovecot 
> for doing the pop3s part.

can we have some numbers?
how many concurrent connections? how did you compile dovecot?
do you use epoll/inotify?

> Dovecot is really fine, but it still isn't NFS ready. Especially when 
> using dovecot as pop3 only this index-stuff must be disengageable. What 
> is the use of generating a complex index file for hundreds of messages, 
> that will be deleted in the next step after downloading them? But the 
> index is also a problem when using IMAP over NFS. Access to the files is 
> too slow, so the connections keep hanging around and the i/o waiting 
> value is raised to a maximum which slows down the whole machine. It 
> simply doesn't make sense to build and update an index every time the 
> maildir is accessed (which is very cpu and timeconsuming), while search 
> operations (the only moment when the index is actually used and not just 
> heavily updated) don't affect even 1% of all IMAP calls (and such a 
> command doesn't even exist for pop3).

for me the index even helps for just opening the folder via imap. having
an up2date index speeds up reading the folder via imap drastically.

did you try to store the indexes locally on the disk? you can configure
that at runtime.

> I would be much obliged if you could create an option called 
> "--disable-index" in the configure-script or something like 
> "disable-index = yes" in dovecot.conf that makes dovecot ignoring 
> existing index files and doesn't care for related operations, so NFS 
> should work much faster and IMAP search would simply parse the files 
> directly instead of looking in the index.
> 
> I would really appriciate this very much and I'm absolutely sure, that a 
> lot of people beside me are waiting for this.

hope this helps.

    darix