Re: limit max. used bandwith?

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limit max. used bandwith?
\ peter pilsl (14 Apr 2007)
. \ (Wietse Venema) (14 Apr 2007)
. \ Sandy Drobic (14 Apr 2007)
. . \ Adam Jacob Muller (15 Apr 2007)

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Subject:	Re: limit max. used bandwith?
Group:	Postfix-users
From:	Adam Jacob Muller
Date:	15 Apr 2007

On Apr 14, 2007, at 2:17 PM, Sandy Drobic wrote:

> peter pilsl wrote:
>>
>> I want to limit the max smtp-connections the postfix-daemon can
>> process
>> simultanously - or even better - the total bandwidht used by postfix.
>>
>> Current problem: a postfix-server is connected to internet on a
>> 500k-uplink DSL-Connection. Now a user sends a 30MB-mail to 1000
>> recipients. This means 30Ggigs of mail over a 500k-connection.
>> The line is dead with traffic.
>
> Set a reasonable message_size_limit, the default is 10MB.
>
>>
>> I guess a limit on connections would not help too much, but bring at
>> least some performance-gain to the connection. I didnt find an
>> option to
>> limit the max. number of smtp-processes that applies to the
>> queues as
>> well.
>> And I didnt find a bandwith-option.
>
> AFAIK there is no option to limit bandwidth, that is the job of a
> traffic
> shaper.
>
> You can of course limit the number of outgoing connections, but it
> will
> not help you with the basic problem, that your available bandwidth is
> rather low.
>
> It might be possible to use a special transport for mass mails with
> only a
> few allowed smtp connections or even hold the mails there and
> release it
> at a convenient time, but those are only bandaid measures.
>
> Your best option at the moment is probably to limit
> message_size_limit.
>
> --
> Sandy
>
> List replies only please!
> Please address PMs to: news-reply2 (@) japantest (.) homelinux (.) com

In this situation, if you actually expect your users to be able to
send 30mb emails to 1000 users (IE: if that's something you want or
need) you should smarthost all your mail to a server with a real
internet connection.
Your still going to end up using 30mbit of bandwidth, use some
traffic shaping to make sure you don't max out your upstream (which
is killing your downstream by stifiling acks), this isn't a bad idea
to do anyway if you can for most (all!) traffic (limit speed of
outgoing streams to 90 (or so) percent of avaliable bandwidth to
prevent queuing of acks for incoming streams)

-Adam