[Mimedefang] really high cpu
jebright at esisnet.com
Wed Feb 9 10:26:52 EST 2005
Not to get into the basic Linux vs the world debate here (Otherwise known as
my OS is better), but:
On Wed, 9 Feb 2005 02:55:31 -0800, John Nemeth wrote:
>>Nah, recent versions of Solaris can easily beat Linux.
>> Load is certainly important, but looking for other things such
>>as whether the machine is swapping is more important. If the machine
>>swaps, get more RAM.
>> The ability to tune a server and eliminate bottlenecks is one thing
>>that seperates professional system administrators from wannabes. If you
>>don't know what you're doing, then you can make any system run slow. If
>>you do know what you're doing, then you can make any system run fast as
>>long as you have decent hardware and a decent OS.
It depends, Have you benchmarked a recent Linux system on comparable
hardware, like I said, you would be surprised. As far as using "server grade"
hardware, that goes without saying. I managed a server farm of over 40
servers, and 3 clusters, mixed OSs, primarily Solaris and Linux. My ISP had
OVER 500,000 customers (yes, 1/2 million) and my region had over 56,000 email
accounts in our cluster. We did WELL over 10,000 messages a day (granted,
this was before MIMEDefang and spam was only becoming a major problem
industry wide when I left). So, unless you have done some unbiased testing,
you can not make the claim above, esp. when it is contrary to much anecdotal
evidence on the net (which I also take with a grain of salt ;-) ).
MIMEDefang does seem to be RAM hungry but this goes without saying, if a
server swaps out much at all, you need to add more RAM or look at your
running porocesses to see what you need to cull. Once a system is tuned, the
best metric to actively monitor (yes, trend them all, but actively monitor)
is load, ALL your other metrics are related to load in some manner. Generally
speaking, if your load is greater than the number of processors in your box,
then you have processes waiting on CPU time (very generally, but this is
probably the best way to look at it for some).
Also, if you are not running a DNS caching server on your sendmail box then
you need to, DNS is a large bottleneck for sendmail, even saving the extra
processes and memory to go out over a LAN to another DNS server and back is
generally worse than running a local caching only daemon.
I mention the hosts file as it is a common mistake made by less experienced
admins, eg: one ISP we purchased had EVERY server they owned and every nodes
IP listed in their hosts file that they updated from a cetralized database...
the hosts file was close to 1MB whch is not all that large, but sendmail
reads that file in something like 3 times for every single message that came
in or out of that server... needless to say... it was causing speed and
I am not saying I know all, and all of our testing was done with Solaris 8,
which I referenced above, I have no experience with Solaris 9, the tuning
sendmail book is a good reference as well, I did not think about it as I am
more familiar with the more archaic bat book as that is what I had available
at the time. We had Solaris 8 pretty fine tuned, we also had Linux fine tuned
as well, and in our benchmarks and live tests Linux smoked Solaris as far as
sendmail was concerned, it was not even close.
At my current venture, we maintain 3 different mail servers including our
own, the largest is still rather modest compared to the systems I used to
maintain, but it comparable to the one you maintain: here are last weeks
general stats for this box:
Date Reject Tx/Rx Spam: Virus
31 Jan 61437 9093 339 112
01 Feb 71665 9800 331 119
02 Feb 61729 9643 376 122
03 Feb 66060 9630 378 112
04 Feb 67957 10453 490 125
05 Feb 61849 5216 390 54
06 Feb 63170 4819 411 46
TOTAL 453867 58654
Rejected mail either bounced from trusted RBLs (i.e. our own and a few
others) or scored so high that we quaranteened and bounced them back (I do
not believe "joejobs" are included in the above stats, which probably means
user unknowns and 4xx rejects are also discluded but I could be wrong, those
are typically a statistically insignificant portion of the totals though if
they are or not and woudl belong in the reject column).
The other categories are self explainatory, the spam one is mail tagged and
delievered (scored high, but not so high as to outright bounce). As you can
see, this server delivers 9-10k messages a day, but processes closer to 80k a
day, it does not even break a sweat, I could double this mail load and still
be fine with no adjustments to hardware and maybe a few software tweaks. The
hardware you ask... a fairly modest Dell Poweredge server, dual 1G PIIIs and
2.5 GB memory using the built in Perc raid card (which I don't care for).
This box ran a load average last week of .31, yes, not even a one... oh, and
it runs Linux.
I agree 100% though, if you don't know what you are doing, you can impede the
performace of any system rather easily.
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