[Dovecot] Converting CLIENT_MAIL_DATA_MAX_INMEMORY_SIZE to a configurable?

[Timo Sirainen]

On Thu, 2011-06-09 at 20:56 +0200, Attila Nagy wrote:
> Hi,
> 
> Currently Dovecot's LMTPd writes incoming emails to mail_temp_dir if 
> it's bigger than 128k. But I would like to spare those unnecessary 
> operations (creating a file, deleting it, writing into it, reading from 
> it, checking whether there is free space and if not, rejecting 
> (temporarily) the message). Memory is cheap, disk IO is not. :)
> And BTW, on a lot of systems, /tmp is a memory file system already, so 
> there is absolute no need for this.

If there's not enough disk space, nowadays the message is read fully
into memory instead of tempfailing.

Also are you sure that writing to the file actually produces disk I/O?
Even if /tmp isn't a memory filesystem, I think there's a good chance
that the file will be gone before any disk writes have a chance to
start. Can you see some measurable disk I/O change by changing this
value?