David F. Skoll wrote:
Kris Deugau wrote:
define(`confQUEUE_LA', `2')dnl
define(`confREFUSE_LA', `7')dnl
Bad settings.
Having REFUSE_LA higher than QUEUE_LA is a surefire way to kill your server.
Most busy SMTP servers are I/O bound, and running in queue-only mode does
nothing to reduce your I/O load. In fact, it *increases* it because the
messages will need to be pulled from the queue at some point in the future.
See "Sendmail Performance Tuning" by Nick Christenson.
If you're running Linux, and those settings work well from you, your
mail server is *not* busy! :-)
*shrug* It's not as heavily loaded as it was at one point; most of the
real "load" was peaky; and accepting and queuing mail was the better
tradeoff than refusing outbound mail connections from customers. :/ (I
*did* try it the other way around for a while, but refusing connections
first causes phone calls asking why $customer can't send email.) Every
so often the load spikes to ~12 or so - usually late at night when the
only mail showing up is inbound mail^Wspam to hosted domains.
It's an all-in-one domain hosting box, so other processes affected mail
processing too.
On another system I had them set to queue at 1 and refuse at 8, IIRC;
for a time it was accepting relay mail from a qmail box that kept
opening *hordes* of parallel connections. It suffered from the same
problem with customer's outbound mail, along with complaints about
delayed *inbound* mail. Queuing the mail meant that, on the whole, mail
got delivered faster. Addition of RBL checks on the qmail system has
dropped the number of relayed messages by ~80% or so. (All spam.)
Ah, legacy systems. <g> Both are to be retired, neither is
misbehaving, and the load on each slowly drops as customers cancel their
service.
-kgd
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