titter 's List: high availability cluster

• One of the most important things to know about MNS is that you must have at least three nodes in the cluster
• when the quorum database is updated, each copy of the database needs to be updated
• also have some serious limitations
• opens the doors to long distance clustering
• each node has its own, locally stored copy of the quorum database
• Majority Node Set Quorum
• new type of quorum
• Windows Server 2003
• The partition that “owns” the quorum is allowed to continue running the application
• cluster is said to have been partitioned
• communications failure
• Normally, each node within a cluster can communicate with every other node in the cluster over a dedicated network connection
• The other thing that the quorum does is to intervene when communications fail between nodes
• tells the cluster which node is currently active and which node or nodes are in stand by
• tells the cluster which node should be active
• two very important jobs
• resides in a file named \MSCS\quolog.log
• a quorum is the cluster’s configuration database

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• appropriate filesystems may need to be imported and mounted, network hardware may have to be configured, and some supporting applications may need to be running as well
• clustering software may configure the node before starting the application on it
• detecting hardware/software faults, and immediately restarting the application on another system without requiring administrative intervention
• operate by having redundant computers or nodes
• purpose of  improving the > >  availability >  of >   services > >
• e > >  availability >  of >    > >
• improving the >  availability >  of >  services >

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• Windows clusters have historically only presented the option of failover services
• The cluster software evaluates the resources of servers in the cluster and chooses which are used based on criteria set in the administration module

• Kerberos authentication against clustered virtual servers
• Windows Server 2003, Enterprise Edition
• not recommended because of Virtual memory (VM) fragmentation
• Active / Active cluster
• Failover process occurs
• heartbeat fails
• Heartbeat communication
• private NIC
• public LAN
• cluster communication
• private LAN
• two network interfaces
• Every cluster node
• If the failed node is back online, a Failback can be manually initiated or automatically configured
• 8 nodes
• nodes supported
• Microsoft recommends only Active/Passive clusters
• • Active/Active or  
  • Active/Passive
• cluster can be
• external disk or disk subsystem
• use a Shared Disk
• All nodes
• use of Cluster Services.
• Windows 2003 Servers
• high availability
• provide
• function as a single computer/system
• nodes
• group of computers
• cluster is

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