On Wed, Mar 06, 2019 at 10:51:04AM +0000, De Petter Mattheas wrote:
> Test os ubuntu 18.04.2 fully patched
Make sure to configure systemd logging with generous rate limits
to avoid losing log messages under load.
> We see when we send 45000 mails form are exchange server to the relay smtp =
> (postfix) that postfix loses about 14000 mails.
As mentioned by Wietse, Postfix does not "lose" mail. You have not
posted any details of your setup, nor explanation of what you're
measuring to determine which messages were accepted and which "lost".
So no further help is possible.
> About 31000 are in are postfix queue and the rest is gone,
How did you configure Postfix to keep every received message? Where
are you looking for the messages? How many inbound messages are
logged?
> we see the confirmation of postfix that he has received the mail is not
> in the postfix queue.
You have not posted any such evidence from the sending client, nor
anything corresponding from the Postfix logs.
> We see a very high I/O on the disk but still writing...
I/O is one of the limiting factors in load tests.
> Which parameter do I have to change to start throttling sow my mails aren't
> lost?
Postfix does not lose email.
> 45000 mails a hour is a real situation where we use the postfix in case of =
> problems with machines and the alerts they send.
45000 an hour is less than 15 msgs/sec. In my tests more than a
decade ago (on correspondingly slower hardware), Postfix was easily
doing ~300 msgs/sec (unsurprisingly, without losing any mail).
Tests with the queue on a RAM-disk and delivery to a loopback sink
topped out at ~3000 msgs/sec with the queue manager running at 100%
CPU. In realistic configurations, you're limited to hundreds per
second by the available I/O bandwidth and ability of downstream
systems to absorb relayed messages.
--
Viktor.
