Autor: Brett Parker Datum: To: exim-users Betreff: Re: [exim] Delaying in answering incoming SMTP
On 21 Oct 07:46, Justin Givens wrote: > Hey everyone,
>
> One of the mail servers I've got here seems to take a while to initiate
> incoming connections on port 25 when load gets even a little bit high.
>
> When the load is low (<10) I can expect to telnet to my mailserver on port
> 25 and see the connection opened and the exim smtp banner near
> instananeously.
>
> However, when the load gets above 10, which it does frequently, we can
> expect to wait anywhere between 1-5 seconds for the connection to be opened
> and the banner to display.
Making the assumption that this is a dual processor box at best... and
probably hasn't got 10 cores, this generally suggests you're IO bound,
i.e. it's disk...
Do you do content scanning at SMTP time? E.g. maybe clamav? If you do,
then the message tends to get written to the disk multiple times, and
this is a fairly hefty penalty - the "easy" solution is to make it so
that the scanning "partition" is actually a tmpfs so that the data comes
in, sits in memory, is processed and then is sent back in to exim
nicely.
