Future enterprise data centers will look like private clouds supporting a flexible and agile execution of virtualized services, and combining local with public cloud-based infrastructure to enable highly scalable hosting environments. The key component in these cloud architectures will the cloud management system, also called cloud operating system (OS), being responsible for the secure, efficient and scalable management of the cloud resources. Cloud OS are displacing “traditional” OS, which will be part of the application stack.
Flexibility in Cloud Operating Systems
A Cloud OS administers the complexity of a distributed infrastructure in the execution of virtualized service workloads. The Cloud OS manages a number of servers and hardware devices and their infrastructure services which make up a cloud system, giving the user the impression that they are interacting with a single infinite capacity and elastic cloud. In the same way that multi-threaded OS define the thread as the unit of execution and the multi-threaded application as the management entity, supporting communication and synchronization instruments; multi-tier Cloud OS define the VM as the basic execution unit and the multi-tier virtualized service (group of VMs) as the basic management entity, supporting different communication instruments and their auto-configuration at boot time. This concept helps to create scalable applications because you can add VMs as and when needed. Individual multi-tier applications are all isolated from each other, but individual VMs in the same application are not as they all may share a communication network and services as and when needed.
A Cloud OS has a number of functions:
- Management of the Network, Computing and Storage Capacity: Orchestration of storage, network and virtualization technologies to enable the dynamic placement of the multi-tier services on distributed infrastructures
- Management of VM Life-cycle: Smooth execution of VMs by allocating the resources required for them to operate and by offering the functionality required to implement VM placement policies
Management of Workload Placement: Support for the definition of workload and resource-aware allocation policies such as consolidation for energy efficiency, load balancing, affinity-aware, capacity reservation
- Management of VM Images: Exposing of general mechanisms to transfer and clone VM images
Management of Information and Accounting. Provision of indicators that can be used to diagnose the correct operation of the servers and VMs and to support the implementation of the dynamic VM placement policies
- Management of Security: Definition of security policy on the users of the system, guaranteeing that the resources are used only by users with the relevant authorizations and isolation between workloads
- Management of Remote Cloud Capacity: Dynamic extension of local capacity with resources from remote providers
OpenNebula is an open cloud OS that provides the above functionality on a wide range of technologies. However, in my view, the main differentiation of OpenNebula is not its leading edge functionality but its open, modular and extensible architecture that enables its seamless integration with any service and component in the ecosystem. The open architecture of OpenNebula provides the flexibility that many enterprise IT shops need for internal cloud adoption. Cloud computing is about integration, one solution does not fit all. Moreover, as pointed out in the CloudScaling “Infrastructure-as-a-Service Builder’s Guide“, the right configuration and components in a Cloud architecture also depend on the execution requirements of the service workload.
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