The VirtuaLinux Project
Diskless Cluster + External SAN
Using EVMS and iSCSI, the architecture provides a flexible, high-level description of the underlying hardware that frees the administrator from the traditional, rigid allocation of resources. Performance and scalability are achieved by means of the direct access of cluster blades to the external SAN via a switched Infiniband network (10-20Gb/s). Storage reliability is implemented within the external SAN, which can exploit a redundant array of disks (disks that can be mounted on the blades are usually quite slow and fragile).
Masterless Cluster Configuration
VirtuaLinux has no master, all nodes have a symmetric configuration. Critical OS services are categorized and made redundant by either active or passive replication in such a way they are, at each point in time, cooperatively implemented by the running nodes. Any node can be hot-swapped with no impact on cluster operativeness and stability.
Cluster Virtualization
VirtuaLinux separates three environments, targeted to different classes of administrators: The physical cluster, including the physical devices, which are insulated and made transparent (hardware technician). The privileged cluster, i.e. the environment that provides services and interfaces to the virtual clusters (skilled OS administrator). The virtual clusters that are sets of virtual machines. They can run any OS and configuration in such a way Grid and Beowulf style virtual clusters can coexist simultaneously (standard OS administrator).
VirtuaLinux Features and Tools
VirtuaLinux provides: A bootable DVD. Distribution independence: Virtual Clusters can run any distribution (currently included virtual clusters: Ubuntu Edgy 6.10 and CentOS 4.4 for x86_64). An install facility to setup and configure the included virtual machine images in a diskless, masterless fashion. A recovery facility able to reset a misconfigured (physical) node to factory status. A toolkit to manage Virtual Clusters, which can be dynamically created, destroyed and moved. User and developer documentation.
The aim:
VirtuaLinux allows the coexistence of many Linux distributions and configurations in the same cluster; moreover, virtual clusters can be saved, restored and moved. Upgrading and testing of the cluster is greatly simplified and requires less time. In addition, fault-tolerance is obtained by a combination of architectural, software and hardware strategies that implement a design with no single point of failure.
