SERVER CLUSTERING

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SERVER CLUSTERING

• Chapter 6

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OVERVIEW

• List the types of server clusters.
• Determine which type of cluster to use for your
  applications.
• Describe how Network Load Balancing and server
  clusters work.
• Deploy an NLB cluster.
• Deploy a server cluster.

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WINDOWS SERVER 2003 CLUSTER TYPES

• Server clusters
• Network Load Balancing clusters

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SERVER CLUSTERS
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NETWORK LOAD BALANCING
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DESIGNING A CLUSTERING SOLUTION

• What are you protecting against?
• Software failure
• Hardware failure
• Site failure

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ESTIMATING AVAILABILITY REQUIREMENTS

• Decide what applications are required, and how
  much downtime can be tolerated.
• Consider what threats may be presentthey will
  not be the same in every situation or
  environment.
• Investment in fault tolerance and availability is
  governed by the laws of diminishing returns.
  Spending twice as much will not provide double
  the protection.

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SCALING CLUSTERS

• Scale up
• Improve performance of systems by installing a
  more powerful processor and adding RAM and higher
  performance disk subsystems.
• Scale out
• Add servers to cluster to increase overall
  processing power.

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HOW MANY CLUSTERS?
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COMBINING CLUSTERING TECHNOLOGIES
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DISPERSING CLUSTERS

• Geographic separation provides higher
  availability in situations such as
• Natural disaster (flood, earthquake, tornado)
• Power failure, rolling blackouts
• Theft, vandalism, terrorism

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USING NETWORK LOAD BALANCING

• Easier to install, configure, and maintain than
  server clustering.
• Does not require additional storage hardware.
• No additional software is required.
• Managed via the Network Load Balancing Manager
  application.

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UNDERSTANDING NETWORK LOAD BALANCING

• Each NLB cluster can consist of up to 32 servers.
  
• A virtual network adapter acts as an intermediary
  between the physical network interface and the
  protocol stack.
• An algorithm associated with the virtual network
  adapter determines which requests should be
  answered and which should be ignored.

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PLANNING A NETWORK LOAD BALANCING DEPLOYMENT
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NLB OPERATIONAL MODES

• Unicast mode
• Servers in the cluster can only communicate with
  each other if more than one network interface is
  installed in the server.
• Multicast mode
• Servers with one network card can communicate
  with each other, but any routers on the network
  must support multicast MAC addresses.

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NLB NETWORKING

• Servers in an NLB cluster determine independently
  whether or not to process an incoming request.
• Servers in an NLB cluster transmit heartbeat
  messages to let the other servers in the cluster
  know they are running and operational.
• Heartbeats are the only cluster-related
  communication between servers in an NLB cluster.

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DEPLOYING A NETWORK LOAD BALANCING CLUSTER
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MONITORING NETWORK LOAD BALANCING

• Monitoring of NLB clusters can be performed
  using
• Network Load Balancing Manager
• Event Viewer

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USING NETWORK LOAD BALANCING MANAGER
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USING EVENT VIEWER
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USING NLB.EXE

• Command line utility used to configure and manage
  NLB clusters
• Enables commands to be placed into scripts and
  batch files

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DESIGNING A SERVER CLUSTER

• Designing a server cluster deployment
• Planning a server cluster hardware configuration
• Creating an application deployment plan
• Selecting a quorum model
• Creating a server cluster
• Configuring failover policies

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DESIGNING A SERVER CLUSTER DEPLOYMENT
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PLANNING A SERVER CLUSTER HARDWARE CONFIGURATION

• All servers in the cluster must be running the
  same edition of Windows Server 2003.
• All servers in the cluster must have the same
  processor architecture 32-bit or 64-bit.
• At least one network interface per system is
  required. Two are preferred.
• Shared storage connection is required.

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USING SCSI
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USING FIBRE CHANNEL
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CREATING AN APPLICATION DEPLOYMENT PLAN

• Single-instance applications
• Applications that can run on no more than one
  server at a time, using a given configuration
• Multiple-instance applications
• Applications in which duplicated code can run on
  multiple nodes in a cluster or in which the code
  can be partitioned

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DEPLOYING SINGLE-INSTANCE APPLICATIONS
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CAPACITY PLANNING

• Idle servers in a standby configuration must be
  capable of running the application(s) on the
  active server.
• Depending on the failover configuration, the idle
  server may be required to run more than one
  application in the event of a multiple server
  failure.

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DEPLOYING MULTIPLE-INSTANCE APPLICATIONS
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SELECTING A QUORUM MODEL

• Single-node cluster
• Single-quorum device cluster
• Majority node set cluster

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CREATING A SERVER CLUSTER
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CONFIGURING FAILOVER POLICIES

• Failover pairs
• Hot-standby server
• NI
• Failover ring
• Random

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CHAPTER SUMMARY

• A cluster is a group of servers that appears to
  users as a single resource and that provides high
  availability, reliability, and scalability for
  specific applications.
• A Network Load Balancing cluster is a group of
  servers running a stateless application, such as
  a Web server, each of which has an identical,
  independent data store.
• A server cluster is a group of servers running a
  stateful application, such as a database server,
  and sharing a common data store.

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CHAPTER SUMMARY (continued)

• Network Load Balancing works by creating a
  virtual network adapter with IP and MAC addresses
  that represent the cluster as a single unit.
• When NLB is running in unicast mode, ordinary
  communication between cluster servers is
  impossible. In multicast mode, the cluster
  servers can communicate normally.
• Although NLB and server clusters can both
  function with a single network interface adapter
  installed in each server, using multiple adapters
  in each server can prevent network performance
  degradation.

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CHAPTER SUMMARY (continued)

• A server cluster requires a storage resource
  shared by the nodes in the cluster. Windows
  Server 2003 supports shared SCSI and Fibre
  Channel for this purpose.
• In a server cluster, the quorum is a storage
  resource that contains cluster configuration
  data, which nodes use to create their
  configuration databases as they join the cluster.
  
• You can configure a cluster to use various
  failover policies by specifying which nodes are
  permitted to run various cluster resources.

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CHAPTER SUMMARY (continued)

• To create and manage server clusters, use the
  Cluster Administrator application. To manage
  Network Load Balancing clusters, use Network Load
  Balancing Manager.