Clusters

Clusters

Alternative to symmetric multiprocessing (SMP)

Group of interconnected, whole computers working together as a unified computing resource illusion is one machine system can run on its own

Clusters

Separate server each computer is a separate server no shared disks need management or scheduling

software data must be constantly copied among

systems so each is current

Clusters

Standby Server with No Shared Disk

High-Speed Message LinkI/O

P

I/OI/O I/OM M

P PP

Clusters

Shared nothing reduces communication overhead servers connected to common disks disks partitioned into volumes each volume owned by a computer if computer fails another computer gets

ownership of the volume

Clusters

Shared Disk

High-Speed Message Link

I/O

P

I/OI/O I/OM M

P PPI/O I/O

RAID

Clusters

Shared disk multiple computers share the same

disks at the same time each computer has access to all of the

volumes on all of the disks

Win2000 Cluster Server

Formerly called Wolfpack Shared-nothing cluster Concepts

Cluster Service – Software that manages cluster-specific activity Resource – Item to be managed

Physical: Disk drives, Network cardsLogical: Volumes, TCP/IP addresses, Applications, Databases

Online – A resource is online at a node when it is providing service on that node

Group – A collection of resources managed as a unitHelps manage resources, load balancingUsually a set of resources needed for a specific application

Win2000 Cluster Server

ComponentsNode Manager – Maintain membership: Uses heartbeat messages to track systemDatabase Manager – Maintain cluster configuration database (resources, groups, ownership): Uses fault-tolerant transaction softwareResource Manager – Make decisions concerning resources, startup, failoverEvent Processor – Connect components

Beowulf

From NASA High Performance Computing and Communications Project, based on commodity hardware

Implemented as an add-on to Linux, and each node runs a copy of Linux, with kernel extensions for global namespaces

Examples of Beowulf system software: Beowulf Distributed Process Space – Allow process ID

space to span machines, provide single system image, start processes on other nodes

Beowulf Ethernet Channel Bonding – Combine multiple low-cost links into a single logical network

Pvmsync – Provide synchronization and shared data objects in a cluster

EnFuzion – Set of tools for parametric computing