System capacity

[Ugo Bellavance]

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Hirsh, Joshua wrote:
>  Since we're on the subject, I was running some performance testing on an HP
> DL380 the other day (dual 3Ghz with 2Gb of RAM and 2 RAID-1 partitions using
> 15k RPM drives).
>
>  I was able to push just under 1200 messages per minute (1.7 million per
> day) using MS 4.35.11 and Postfix 2.1.5, SA 3, DCC, Razor and RBLS. For my
> tests I made the following changes to the system:
>
>  Caching nameserver
>  Ran nscd
>  Set /var/spool/MailScanner as tmpfs
>  Disabled atime record keeping on /var/log
>  Disabled syslog synching in /etc/syslog.conf
>
>
>  I only had a chance to test Sendmail and Postfix at the time. I'll try out
> Exim at another date. However, I couldn't get Sendmail to run anywhere near
> the performance levels I saw with postfix. I could only get Sendmail to run
> with 400 messages per minute with the system configured identically.
>
>  Even without MailScanner, Sendmail performed extremely poorly. As a pure
> relay server, Postfix was able to handle close to 2400 messages per minute
> (almost 3.5 million per day). Sendmail could only make it up to 900 messages
> per minute.
>
>  The system was configured to relay all data to another server running
> smtp-sink.
>
>  Email was generated using Postal with random sizes of up to 100k per
> message from various source machines.
>
>  With MS running, the load average with Postfix was around 12, however
> messages were still being sent with a very minimal delay (one minute at
> most). During the Sendmail test, the load was around 15 to 16 and messages
> were being delivered with an average delay of 3 to 5 minutes.
>
>  Without MS running, the load average with Postfix was 4. With Sendmail, the
> load was around 8 to 12.
>
>
>
>
>
>  Now of course, take all performance measurements with a grain of salt,
> unless you run them for yourself. Every system is different and every
> configuration of said system will interoperate differently. These are just
> my own figures that I've run across during my own performance testing. I'm
> sure Sendmail could have been tweaked to work better, but I ran both MTA's
> "out of the box" with default configurations (except for defining a relay
> and transport host).
>
>  Real world production is always going to be different from testing like I
> did. For one, I'm not Sendmail email from hundreds to thousands of different
> source addresses like a real system of this size would expect to receive, so
> the caching of RBL lookups only has to remember a handful of hosts during my
> tests.

Did you changed the setting in sendmail that makes it stop process mail
when load reaches 12?

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