Load Balancing/HTTPMon

[Chris]

I've got two Win2k servers running IIS 5.0 and MS load balancing.
Each server hosts a static web site. Because Load Balancing itself
does not monitor for service failures, my task is to monitor IIS so
that if the web site should go down on one server, that server will be
removed from the cluster. From what I've read, HTTPMon coupled with
wlbs commands is a possible solution for this problem. However, I am
curious how this would work.

Although both the servers have 2 network cards, only one is enabled on
each server. There is no "private" connection between the servers for
heartbeats. Because the server is in Unicast mode, I understand that
they are not exchanging heartbeats. I am prepared to add this
connection, but we do not want to enable Multicast mode.

The currently enabled nic in each system is configured with 2 IP
addresses - 1) unique for the local system and 2) the shared cluster
IP. The web sites are associated with the shared cluster IP (as
opposed to <all unassigned>). If I were to set HTTPMon to monitor the
sites in this configuration, my understanding is that it would not be
able to tell which server it was monitoring.

Can I work around this by enabling the 2nd nic? Would I then also
have to change the IP address for the web site on both servers to <all
unassigned> so that HTTPMon can monitor each instance through the 2nd
adapter? Instead of a crossover between the two, I guess I'd have to
plug the 2nd nics into the switch so they can be monitored by a 3rd
computer (outside the cluster) running HTTPMon.

Thanks for any advice.

 

[Marc Reynolds [MSFT]]

Hi Chris,

This article should help you with setting up HttpMon:

259651 How to Configure HTTPMon to Monitor NLB or WLBS Web sites
http://support.microsoft.com/?id=259651

one point though:

You said, "There is no "private" connection between the servers for
heartbeats. Because the server is in Unicast mode, I understand that
they are not exchanging heartbeats."

This is not correct, the NLB hosts exchange heartbeats over the clustered
connection, not the private connection (even if you have multiple NICs
enabled).

Thanks,
Marc Reynolds
Microsoft Technical Support

This posting is provided "AS IS" with no warranties, and confers no rights.
--------------------

 

[Chris]

From the article you referenced:

"NOTE: HTTPMon should not be installed on a cluster node. If the
computer with both the cluster node and HTTPMon becomes unavailable,
you are not able to monitor using HTTPMon. Also, if you are using a
single network card configuration in Unicast mode, communication
between nodes is disabled. In this case, you are not able to monitor
using HTTPMon, even if the Web site is available."

It says communication between nodes is disabled. Does this mean all
communications *except* heartbeats?

I have seen that doc and will certainly use it when configuring
HTTPMon, but my question was regarding the setup for the NLB hosts.
Specifically, I wanted to 1) confirm that enabling the 2nd nic was the
way to go and 2) find out how to set up the IP Address under the
properties for the web sites in IIS.

 

[Chris]

Thanks for the heartbeat tip - I found an MS doc (Load Balancing
Technical Overview) that cleared things up. It also says that traffic
for a cluster host's dedicated IP (on the cluster adapter) is received
by all cluster hosts, but then discarded by tcp/ip on the other
servers. I take this to mean that I can use HTTPmon (from a computer
outside the cluster) to monitor web sites on specific cluster hosts,
as long as the web sites are bound in IIS to the dedicated IP
address... if so, then at least I'd know when IIS services stopped.
If I'm still off, or if someone could tell me how to monitor web sites
bound to the cluster IP address on specific cluster hosts, please let
me know.

Thanks again for your response. I have researched this quite a bit,
but I haven't felt like I understand it well enough to go ahead with
any changes.

 

[Guest]

Marc,
Thanks for the link. But in this article, it mention about HTTPMon version 3.08b and HTTPMon program in Windows 2000 Resource kit is version 2.
The version in W2K resource kit does not have option "EnableSingleIP" and it does not explain clearly on how to configure so that HTTPMon will automatically remove node from cluster when this HTTP service on this node stops nor rejoin this node to cluster when HTTP service become available again
Please Help and if possible can you please so kind to email me
Thanks

J

 

[Guest]

I figured out my problem. I installed the software from the wrong httpmon directory

one problem is that when I take the server with high priority in the LB off line (stop www service). The server is not removed from the Load Balancing but instead show as stopped. In result, traffic is still directed to this server
How can I remove this server from the LB or it will LB will remove it after a period of time
Thanks for all responde
JJ