Windows 2008 Clustering – Now a day’s lot of organization
are heavily dependent on redundancy in case of hardware/ Service failures on
critical servers, So they plan for Workaround or provide actual solution to
problem, Windows 2008 clustering provides the solution for redundancy & it
really depends on how the clustering is configured in your environment, In
order to understand clustering in details you need to first know the basic
& most important concepts mentioned below-Again lot of Windows services
i.e. DNS,DHCP, exchange are cluster aware & lot of third parties are also
making their applications windows cluster aware to provide cluster support for
higher availability of services.
This article is very helpful to someone who is new in
clustering & wants to know the clustering concepts
Cluster—a
cluster is a group of servers that are presented to the network as a single
system.
Node—A node is an
Single server that is a member of a cluster
Cluster resource—a
cluster resource is a service, application, IP address, disk, or network name
defined and managed by the cluster.
Virtual cluster
server—a virtual cluster server name is the virtual name where the
workstations connect to the server; it is configured as virtual which
represents all the servers that are running in clustering.
Active node—an
active node is a node in the cluster that is active in cluster & the rest
of servers are acting as passive.
Passive node—a
passive node is the server where no services are running & clients are
actually connecting to active node
Active/passive
cluster—An Active/Passive cluster is configured where one node is active
and another node is passive and waiting for failover to happen
Active/active cluster—this
is the configuration where both nodes are active at the same time &
workstations are connected to them.
Cluster heartbeat—This
is critical as this determines failover & fallback as the communication
between the nodes is sent through this private communication, It constantly
look for services that are running on server & if it found some problems
than failover happens to next available node.
Cluster quorum—In
short it holds configuration of clustering & if it fails than entire
cluster gets failed, Very important configuration
Shared storage—shared
storage means the disk that are allocated to cluster node as LUN’s
LUNs—LUN is the
shared drive from External Storage presented to Cluster Nodes
Failover—In case
of nay issues encountered failover is the technique of moving resources from
Active node to passive node.
Failback— once
the Node is active that has failed than the process of moving from current
active node to failed active node is called as Failback process
New features in Windows 2008
clustering
Some of the New features with Windows2008 Clusters:
(1)Create cluster wizard, for creating clusters
(2)Cluster Validate Tool
(3)X64-based Windows2008 Clusters, support up to 16 nodes
in a single cluster
(4)Heartbeat process is done by unicast format providing
more security of nodes in the cluster
(5)Supports IPv6- IP address of the nodes can be in
different subnets, So that Geographical clusters can also be configured.
(6)Cluster Service can be run using the local system
account instead of the Domain service account
(7)Built well to work with SAN storages
(8)Migration of Legacy clusters
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