Eucalyptus Architecture: Cloud Level

Cloud Level

Cloud Controller (CLC)

The Cloud Controller (CLC) is a Java program that offers EC2-compatible SOAP and Query interfaces, as well as a Web interface to the outside world, for distribution within the cloud architecture. In addition to handling incoming requests, the CLC acts as the administrative interface for cloud management and performs high-level resource scheduling and system accounting. The CLC accepts user API requests from command-line interfaces like euca2ools or GUI-based tools like the Eucalyptus User Console and manages the underlying compute, storage, and network resources. Only one CLC can exist per cloud.

The CLC handles high-level:

  • Authentication
  • Accounting
  • Reporting
  • Quota management


Walrus, also written in Java, is the Eucalyptus equivalent to AWS Simple Storage Service (S3). Walrus offers persistent storage to all of the virtual machines in the Eucalyptus cloud and can be used as a simple HTTP put/get Storage-as-a-Service solution. There are no data type restrictions for Walrus, and it can contain images (i.e., the building blocks used to launch virtual machines), volume snapshots (i.e., point-in-time copies), and application data. Again, only one Walrus can exist per cloud.

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