Clustering Technology For Fault Tolerance

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Clustering TechnologyFor Fault Tolerance

• Jim Gray
• Microsoft Research
• http//www.research.Microsoft.com/Gray

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What is Wolfpack?

• A consortium of 60 HW SW vendors(everybody who
  is anybody)
• A set of APIs for clustering and fault tolerance
• An enhancement to NT Server (in beta test )
• Key concepts
• System a particular node
• Cluster a collection of systems working together
  
• resource a hardware or software module
• resource dependency one resource needs another
• resource group fails over as a unit
  dependencies do not cross group boundaries

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What Wolfpack Supports in V1

• two node failover (twin-tail SCSI)
• Apps
• File, Print, web server, IP address, Net Name
• Most of Microsoft BackOffice (SQL, Exchange,
  Viper, Falcon,)
• Oracle
• SAP
• many others
• Easy to program, operate, use

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Cluster Advantages

• Clients and Servers made from the same stuff.
• Inexpensive Built with commodity components
• Fault tolerance
• Spare modules mask failures
• Modular growth
• grow by adding small modules
• Parallel data search
• use multiple processors and disks

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What Happens When a Component Fails?

• Redundant disk or path configure around it.
• Non-redundant software restart.
• Non-redundant hardware migrate software to
  surviving nodes.
• Fault detection 1 ms to 10 sec.
• Failover .1 sec to 1 min.
• This is standard in Tandem, Teradata, VMScluster