| Using ClusterCATS |
|
|
Before You Begin |
|
| Using ClusterCATS |
|
|
Before You Begin |
|
The ClusterCATS technology provides robust features for website availability, load balancing, and failing-over servers.
A website is no longer just a web server. Most websites have moved beyond static HTML pages on a web server. To generate dynamic content or process transactions, a website now includes multiple resources - web servers, files, applications, databases, and other software processes on multiple servers in one or more locations. The move to a more advanced site, consisting of multiple resources, often from multiple vendors, introduces a major problem - overall site availability and performance. More resources, especially software resources, and more links between them exponentially increase the probability of failure. Creating a fast, reliable website becomes substantially more challenging.
Macromedia created ClusterCATS, a complete website resource management solution, to enable service level agreements offering 24x7 availability and optimal response time for e-commerce, customer self-service, sales automation, customer support, and other critical business functions. With ClusterCATS, you can build and manage advanced websites, consisting of multiple resources spanning multiple servers, in one or more locations.
ClusterCATS builds and manages clusters. A cluster is a group of website resources, including web servers, files, applications, databases, and even the network, that act in unison, providing reliable and rapid user access. These resources can be clustered in a single building, distributed in a local area network (LAN), or distributed in a wide-area network (WAN) in multiple locations across the world. A cluster intelligently detects and transparently shields users from the following critical problems:
ClusterCATS delivers critical capabilities required by advanced websites today. These capabilities produce important benefits in the areas of website performance, availability, manageability, and scalability.
User response time is accelerated with ClusterCATS application and server load management.
ClusterCATS consists of server and client components. The ClusterCATS Server runs as a Windows service and ISAPI filter, NSAPI plug-in, or Apache module. ClusterCATS Explorer is the client-based management application used to build and manage clusters. Operating in conjunction with an administrative agent on each ClusterCATS Server, ClusterCATS Explorer provides all the required tools for centrally managing one or more clusters from any location.
You can also configure ClusterCATS software to enhance simple web server load-balancing products, such as Cisco's special-purpose LocalDirector hardware device.
The following table introduces the ClusterCATS capabilities:
ClusterCATS improves user response time by managing application load and web server load across multiple servers.
You establish load management policy through two administrator-defined response time thresholds. You configure these for each server. One threshold sets the level at which load management is activated. If this level of activity is reached, ClusterCATS gradually redirects a percentage of new server requests to the least-loaded server.
The other threshold defines the peak, or maximum, load level. This is defined as the load level that should not be reached on that server. If this threshold is attained, an alarm is sent and requests is redirected.
For some applications, it is important that a user session is completed on one server. ClusterCATS offers a session state management option that ensures that the same web server services requests from a user. When enabled, this option sends the user to the best-performing server. The user session then remains on that server until completion.
ClusterCATS defines a new session for the following:
This approach has distinct advantages over other methods, such as using a source IP address to define a user session. The ClusterCATS definition of a session is particularly beneficial if many visitors come from a large proxy server (for example, America Online). In that scenario, web servers could easily become overloaded.
Should user state be lost completely due to a resource failure, ClusterCATS provides graceful state failover. This capability automatically displays an administrator-defined URL for a custom HTML page or JRun page upon resource failure. This page can be designed to apologize for the failure and, if replicated resources are available, direct the user to restart the application at the beginning via a specific URL.
ClusterCATS uses a distributed operations model, eliminating traffic bottlenecks and maximizing performance. While other hardware and software load-balancing solutions force all user requests and, typically, all responses through a single special-purpose network device or server, each ClusterCATS Server can receive a request, respond to a request, manage traffic load, and support failover. Unlike hardware load-balancing solutions, ClusterCATS performance is not throttled by network media limitations and ClusterCATS is network media independent. Consequently, performance scales linearly as servers and resources are added.
ClusterCATS Explorer, operating in conjunction with an administrative agent on each ClusterCATS Server, provides all the required tools for building and managing a website from any location, whether it be an operations center, hotel, or home.
ClusterCATS Explorer features a familiar Windows Explorer-like user interface and provides both detailed and high-level status views of one or more websites and all resources within a website.
ClusterCATS Explorer views include:
ClusterCATS includes a comprehensive core set of features and offers several add-on options for extending its capabilities. All ClusterCATS configurations include: