Facing the Challenges of Clustering
The statement about strength in numbers is validated daily in many pSeries* environments. Several of these enterprises rely on computer clusters to fulfill their problem-solving and number-crunching needs. However, the process of managing computer clusters can be filled with challenges.
There's strength in numbers, but there's also beauty in simplicity. That's where IBM's Distributed Commands Execution Manager (DCEM) fits in. The DCEM is designed to help enterprises manage server clusters. This article introduces the DCEM and examines its many capabilities.
The DCEM is a GUI for running individual commands or scripts remotely across a cluster of pSeries and/or xSeries* servers managed by IBM's Cluster Systems Management (CSM) solution. The command run by the DCEM uses a remote shell (dsh), which can use the default AIX* remote shell (rsh) or the secure shell (ssh).
By specifying individual machines, administrators can receive real-time command status as well as browser-based execution reports. A command specification (scripts of commands) can be created, deleted, saved or edited from the GUI. A collection of machines can be saved as a group for reuse. The group may be static (based on machine names) or dynamic (based on machine attributes).
DCEM System Functionality
The DCEM GUI (see Figure 1) provides a variety of services for a network of distributed machines. It allows users to construct command specifications to execute on multiple target machines, providing real-time status as commands are executed. Users can enter the command definition, run-time options and selected hosts and groups, and choose to save this command specification for future use. When a command specification is saved, a PERL script is generated that can be run directly from an AIX or a Linux* command line. Groups of hosts can be created and modified to use as targets for a command directly from the DCEM--these groups also can be specified by supplying group host names or using dynamic queries on specific host attributes in a domain.
In addition, the DCEM allows administrators to view RAM, CPU and disk statistics and uses the system error log to perform problem-determination tasks such as examining device information and listing and killing processes. By writing commands and scripts using the DCEM, administrators can broadcast messages and check or change the file system.
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