NLB Behavior

NLB Behavior

Post by Jonty Gold » Wed, 26 Nov 2003 09:37:46

I have been running some performance tests on a web-farm
with two hosts, to determine if NLB is working as
expected. I have noticed some unusual behaviour during
these tests.

During the test I remove one of the the hosts, observe the
load redistributing, then reconnect the host, and observe
the load balancing. I monitor the counter: Web Service >
Current Connections in Performance Monitor, for each of
the hosts in the web-farm cluster.

When I disconnect the host, the load on the connected host
increases (after a period of convergence) as expected.
When I reconnect the removed host, the load on the
existing host drops to it's original load, as expected,
but it takes about 2 - 3 minutes for the reconnected host
to take on any of the load.

Does anyone know why there is such a long delay? I have
played around with session timeouts in the ASP
configuration files (web.config), to no avail.

Any explinations would be welcome.

Thanks in Advance.

NLB Behavior

Post by curtisk » Thu, 27 Nov 2003 01:15:22

Hi Jonty,
For the most part this has to do with the TCP/IP sessions resetting after a
given time and not with the application that is being load balanced. You
should consider this normal behavior as it takes time for the TCP session
to end and a new request to be sent that can then be hosted by the
restarted node.
This posting is provided "AS IS" with no warranties and confers no rights.
Please reply to the newsgroup so that others may benefit. Thanks!