Bb Vista Health Checks 101

1. The load balancer health checks are configured on the load balancer. You see them in your webserver.log file as

Date/Time IP Address 200 GET /webct/checkStatusForLb   guest

The interval is usually 10 seconds.

They’re used by the load balancer to determine whether a user requesting a session should be sent to that node or not. If the node doesn’t respond, end user sessions aren’t sent there.

Weblogic also does health checks. A couple of different kinds it turns out. Here’s where you find them in your Weblogic Console:

2. Peer Connectivity. How are my sister nodes? Are they available to replicate my end user sessions if I’m unable to handle them all?

Left Panel > Environment > Servers > Click on Configuration tab, Tuning sub-tab and hit the Advanced portion at the bottom of the screen to reveal all. We’re interested in the Period Length and the Idle Period Until Timeout

By default, as I mentioned Friday, in Bb Vista (8.0.3 is the one I checked) this is set to broadcast once a minute (60000 milliseconds) and to consider the peer unavailable if 4 messages are lost.

As far as I can tell, our cluster has suffered no ill consequences if a node thinks its peer is gone. Probably because our loads are quite small and because the load balancer’s health checks are still indicating the node is able to receive end user sessions.

3. Domain or Cluster Health. The admin is also asking managed nodes whether they are still participating in the cluster, and probably whether the designated JMS node is still running the services the Admin believes it to be.

Left Panel > Environment > Servers > Click on Configuration tab, Health Monitoring sub-tab (scroll to the right)

By default the health check interval is every 180 seconds . Auto-restart is also enabled so that the Node Manager application could automatically attempt to restart the node services or the server itself if the node does not report appropriately. (I think that’s the best way of saying it). I have a feeling this setting is used by other settings…

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One response to “Bb Vista Health Checks 101

  1. For our load balancer health checks, we picked another approach. One piece looks at /entry_page.jsp for which I like looking at checkStatusForLb better.

    We also have Apache web servers installed on the node for serving up our Sorry Service, the load balancer directs traffic here when the whole pool is down. Also hosted by Apache are up-down pages whereby we direct the load balancer to consider a node up or down. Should our monitoring determine a node need a break from normal traffic, I can mark that node down and cause traffic to divert to other nodes before there is a real problem. It can stop receiving other work without having to shut down the node.

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