On Thu, 1 Apr 1999 01:26:19 -0500, Dave Teske wrote:
>Does anyone know of any apps that can do load testing on mail servers. I've
>seen a bunch that do web server load testing but none for mail servers. I've
>got our server on a tiny (486 w/P90 upgrade chip & 24mb ram)box and I'd like
>to see how much load it'll handle before I go scrounging for a replacement.
qmail is an excellent tool for this. Just set up another computer with
qmail and a concurrencyremote as high or higher than the max number of
connections you can accept on the test machine. Set up an ezmlm list on
the test machine. Subscribe a lot of users test-123@testhost, over a
range of "123". Set up a user "test" on testhost. Create
~test/.qmail-default with a single "#" in it.
Send a message to the list on the other computer. It will send as many
messages as there are subscribers to the test machine. It does less
disk work that the test machine since it sends the same message to all
subscribers. The test machine receives the messages, queues them, then
delivers them discovering that the "#" which means that the delivery
succeeds without writing anywhere.
Thus, you test the [local] network, qmail-smtpd, queue and queuing,
that you have memory for the set number of incoming connections, etc.
For outbound mail, you can reverse the function of the two boxes.
Do yourself a favor and set it up with tcpserver and daemontools
(cyclog) directly. Otherwise, syslog may become limiting and you are
slow on incoming connections and have less control over the number.
Also, carefully read tcpserver docs on -H -l, etc.
What isn't tested: outside net, named (run a caching one locally).
Still, it tells you a lot, especially to what to limit the nuber of
incoming connections (tcpserver -c) and outgoing
(concurrencyremote/local) so that you don't run out of memory at
maximum load.
-Sincerely, Fred
(Frederik Lindberg, Infectious Diseases, WashU, St. Louis, MO, USA)
