MS Performance

Peter Peters P.G.M.Peters at
Tue Jul 15 09:10:10 IST 2003

On Mon, 14 Jul 2003 09:30:11 -0700, you wrote:

>We relay about 500k emails a day through 2 MS machines running redhat &
>sendmail. Both machines are dual Xeon/1gb RAM/SCSI, RAID1
>About 45% of the total incoming mail is spam, half of which is deleted.

We relay about 200k a day through 2 machines running MS, f-prot and SA.
One system is a Celeron 1.3G. The other one is a dual Xeon 2.4G. Both
have 1G RAM. The second server also does nameserving, radius and dhcp.

The load allmost never reaches 1.

We have 1/3 spam which all are delivered to the intended recipient.

>With the exception of the following, it's a default rpm install:
>Max Children = 15

Kept it at 5

>Log Spam = yes (since we need the logs for stats.)
>MS Spam Action is "attachment, deliver".

Just deliver.

>If one rbl goes down or is slow, we found that we very quickly had a
>backlog of 20k messages, so we've turned off rbl checks in SA. Adjusting
>the timeouts for rbl checks may be a better solution.

We have disabled rbl's in SA but we have a total of 17 RBL's in MS.

>The load average when the machines are sharing the mail load is usually
>about 3-4, rising to about 10-15 when one machine handles the full load
>by itself. Everything seems to fit into memory, there is no swapping to
>disk, and the average delay for a message being relayed is < 1 minute.

A message that is checked for all RBL's and is spam according to SA and
one RBL is through in 13 seconds.

>Another bottleneck is the way 'user unknowns' are handled. Currently,
>because mail is relayed through the MS boxes, the MS boxes don't know if
>the user exists at the domain or not. So MS spends time scanning mail
>that is destined for a user that doesn't exist. Next Sendmail tries to
>deliver it and it is rejected by the destination mailserver. Then
>sendmail tries to bounce it back to an address that usually doesn't
>exist, or a mailserver that is not accepting connections or can't be
>resolved. Using re-mqueue to re-queue outgoing mail is helpful with this

We have all excisting users (with a few exeptions) in the virtusertable
on the mailservers. It keeps the number of message a bit down (4000 a

We also block a number of sites, addresses etc before it reaches MS.
Appr. 2500 attempts a day.

These figures are from today, extrapolated for 24 hours. You should also
take in consideration that it's holiday overhere so the numbers are a
bit off.

Peter Peters, senior netwerkbeheerder
Dienst Informatietechnologie, Bibliotheek en Educatie (ITBE)
Universiteit Twente,  Postbus 217,  7500 AE  Enschede
telefoon: 053 - 489 2301, fax: 053 - 489 2383,

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