1. Clusters

2. zAlternative to symmetric multiprocessing (SMP) zGroup of interconnected, whole computers working together as a unified computing resource yillusion is one machine ysystem can run on its own

3. Clusters zSeparate server yeach computer is a separate server yno shared disks yneed management or scheduling software ydata must be constantly copied among systems so each is current

4. Clusters Standby Server with No Shared Disk High-Speed Message Link I/O P MM PPP

5. Clusters zShared nothing yreduces communication overhead yservers connected to common disks ydisks partitioned into volumes yeach volume owned by a computer yif computer fails another computer gets ownership of the volume

6. Clusters Shared Disk High-Speed Message Link I/O P MM PPP RAID

7. Clusters zShared disk ymultiple computers share the same disks at the same time yeach computer has access to all of the volumes on all of the disks

8. Win2000 Cluster Server zFormerly called Wolfpack zShared-nothing cluster zConcepts yCluster Service – Software that manages cluster-specific activity yResource – Item to be managed xPhysical: Disk drives, Network cards xLogical: Volumes, TCP/IP addresses, Applications, Databases yOnline – A resource is online at a node when it is providing service on that node yGroup – A collection of resources managed as a unit xHelps manage resources, load balancing xUsually a set of resources needed for a specific application

9. Win2000 Cluster Server Components Node Manager – Maintain membership: Uses heartbeat messages to track system Database Manager – Maintain cluster configuration database (resources, groups, ownership): Uses fault-tolerant transaction software Resource Manager – Make decisions concerning resources, startup, failover Event Processor – Connect components

10. Beowulf zFrom NASA High Performance Computing and Communications Project, based on commodity hardware zImplemented as an add-on to Linux, and each node runs a copy of Linux, with kernel extensions for global namespaces zExamples of Beowulf system software: yBeowulf Distributed Process Space – Allow process ID space to span machines, provide single system image, start processes on other nodes yBeowulf Ethernet Channel Bonding – Combine multiple low-cost links into a single logical network yPvmsync – Provide synchronization and shared data objects in a cluster yEnFuzion – Set of tools for parametric computing