MACROMEDIA COLDFUSION 4.5-ADMINISTRING COLDFUSION..., Manual

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174 Administering ColdFusion Server
This section describes the following topics:
•
The ClusterCATS offline maintenance mode defined
•
Understanding static and dynamic IP address configurations
•
Configuring offline maintenance support (Windows NT only)
The ClusterCATS offline maintenance mode defined
ClusterCATS provides an offline maintenance feature (available on the Windows NT
platform only) that requires you to perform some initial IP address configurations
before being able to use the feature. You are not required to configure maintenance
addresses in order to use ClusterCATS. However, Allaire highly recommends that you do
so because maintenance IP addresses:
•
Guarantee that you can always access servers in your cluster remotely if they
fail or become unavailable.
Binding a static IP address to the server ensures that you can always access the
box even if the Web server on it fails.
•
Allows you to perform maintenance and server-update tasks without
disconnecting servers from the network.
By placing a clustered server in maintenance mode, you can perform necessary
software updates or configurations while ensuring that your site remains up
and servicing your customers.
•
Prevents your site from experiencing long down times on failover recovery.
Without maintenance addresses your site will experience three to five minutes
of downtime on failover recovery due to an automatic system reboot that
occurs when a system comes back online following failover.
Once you put a server in maintenance mode, all inbound HTTP traffic heading for the
affected server is redirected to the most available server in the cluster. After you
complete your maintenance tasks and take the server out of maintenance mode, the
servers that temporarily assumed the restricted server’s IP address and HTTP traffic
return the IP address back to the affected server so that it can receive and process
HTTP requests.
Understanding static and dynamic IP address configurations
Each server that you add to a cluster must have an Internet protocol (IP) address
defined for it. Because the Internet operates on a TCP/IP network protocol for sending
and receiving packets of data to and from networked computers, you must correctly
define your servers’ IP addresses so that they can send and receive network data as
intended.
The static address must be assigned to the server itself — the physical box. You do so by
making an entry in the server’s IP stack. On Windows servers, you add this IP stack
entry using the Network icon in the Windows Control Panel. This Network icon is also
commonly referred to as your Network Interface Card (NIC). In addition to assigning
the server’s static address, you must make sure that the Web sites’ static IP addresses
that reside on the Web server on this machine get removed from the IP stack (also via