Installation topologies
With WebSphere® eXtreme Scale, you can create many installation topologies that include stand-alone servers, WebSphere Application Server, or both.
Development node
The simplest installation
scenario is creating a development node. In this scenario, you install
the client and server installation of WebSphere eXtreme Scale one time on the node
where you want to develop your application.
After you complete the installation on your development node,
you can configure your development environment and begin writing your
applications.
Stand-alone topology
A stand-alone topology consists of servers that are not running on WebSphere Application Server. You can create many different stand-alone topologies, but the following topology is included as an example. In this topology, two data centers are present. In each data center, WebSphere eXtreme Scale full installations (client and server) and client-only installations are installed on the physical servers. The client-only installations are on the nodes that are running the web applications that are using the data grid. These nodes do not run any catalog or container servers, so the server installation is not required. A multi-master link connects the two catalog service domains in the configuration. The multi-master link enables replication between the shards in the container servers in the different data centers. Advantages to using a stand-alone topology:- Flexible integration options that can be embedded with vendor frameworks and libraries.
- Smaller footprint than a WebSphere Application Server topology.
- Fewer licensing requirements than a WebSphere Application Server topology.
- Expanded Java Runtime Environment (JRE) options.
WebSphere Application Server topology
You can also create an installation that runs entirely in a WebSphere Application Server cell. The clients, catalog servers, and container servers each have an associated cluster. The nodes that run the application have the client-only installation. The other nodes have the client and server installation. Advantages of using a WebSphere Application Server topology.- Centralized and consistent administration and configuration.
- Security integration.
- Java EE application integration.
- Performance monitoring infrastructure (PMI) integration.
- Integration with the following WebSphere Application Server components: OpenJPA L2 cache, dynamic cache, and HTTP session persistence.
Mixed topology
You can create a mixed topology that contains both WebSphere Application Server and stand-alone servers. In the following example, the client applications are running in the WebSphere Application Server cell, while the catalog servers and container servers are running in stand-alone mode.Virtual image topology
WebSphere eXtreme Scale is capable of being used effectively in a
virtual product environment, such as VMWare. However it is critical to keep in mind that eXtreme Scale is a stateful distributed system and therefore
certain criteria must be maintained for effective usage:
- eXtreme Scale is intended to run with a stable network without significant interruptions and has built-in mechanisms to ensure high availability and recover from outages. However, these recovery mechanisms are not without risk of brief service interruption or potential data loss. Also, outages that affect a significant percentage of the eXtreme Scale JVMs in the data grid can result in the resources within the remaining data grid servers being overrun, compromising the entire data grid. Therefore, be careful to ensure that any utilities used by the virtual product in which eXtreme Scale is installed does not dramatically affect network connectivity.
- Be sure to allocate enough CPU resource or memory. For example, a virtual machine with 16 GB of physical memory should not be configured with 4-4 GB eXtreme Scale JVMs, since this does not take into account overhead. Similarly, a host machine with 16 GB of physical memory should not be configured with 4-4 GB guest virtual machines.
- eXtreme Scale is designed as a distributed and balanced data grid product. When the product is configured and sized appropriately there is an expectation that sufficient resources will exist during run time. When the resources become unavailable, the system begins processing failover operations to recover state. Depending on the type and duration of the loss of resources, the system might take dramatic action to attempt to recover because the loss of those resources can indicate significant losses of system infrastructure.
- The distributed nature of the eXtreme Scale data grid means that specific data and underlying infrastructure might be moved from JVM to JVM as additional resources are configured or the infrastructure accounts for failover work. Therefore, utilities used by the virtual product (for example, VMWare Snapshot) that record memory and state within a virtual machine as a backup mechanism, and do not take into account the distributed stateful nature of the system, must be avoided.