Windows
Clustering Implementation
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Devendra
Ozarkar dwells on the subject of Clustering Technology
and C-DAC’s plans to introduce the same in some of
it’s product developments.
High
Availability has become an important aspect for deployment
of business-critical e-commerce and line-of-business
applications. Clustering technology provides high
availability, scalability, and manageability.
A
cluster is a group of independent computers that work
together to run a common set of applications and provide
the image of a single system to the client and application.
The computers are physically connected by cables and
programmatically connected by cluster software. These
connections allow computers to use fail over and load
balancing, which is not possible with a stand-alone
computer.
In
the Windows 2000 Advanced Server and Datacenter Server
operating systems; Microsoft introduces two clustering
technologies viz. Cluster Service and Network Load
Balancing Service that can be used independently or
in combination.
The
Cluster service is intended primarily to provide fail
over support for applications such as databases, messaging
systems, and file/print services. Cluster service
supports 2-node fail over clusters in Windows 2000
Advanced Server and 4-node clusters in Data center
Server. Cluster service is ideal for ensuring the
availability of critical line-of-business and other
back-end systems, such as Microsoft Exchange Server
or a Microsoft SQL Server 7.0 database acting as a
data store for an e-commerce Web site.
The
Network Load Balancing Service provides scalability
and high availability to enterprise-wide TCP/IP services,
such as Web, Terminal Services, proxy, Virtual Private
Networking (VPN), and streaming media services. This
service load balances incoming IP (Internet Protocol)
traffic across clusters of up to 32 nodes.
We
are planning to introduce clustering technology in
FACET (Fundamental Analysis based Capital Enhancement
Tool). A Department of Information Technology funded
project to study / Analysis of Economic, Industry
and Company conditions in an effort to determine the
value of a company stock.
We
will be configuring both Windows Clustering technologies
in conjunction to create highly scalable and available
n-tier e-commerce sites.
 As
shown in Fig. 1. Network Load Balancing Service will
be implemented across a front-end web server farm.
NLB transparently partitions the client requests among
the hosts and lets the clients access the cluster
using one or more "virtual" IP address.
From a client’s point of view, the cluster appears
to be a single server that answers client request.
Performance
can be scaled by plugging additional servers as and
when required.As indicated in Fig.2. A Cluster Service
is planned for the back- end server having business
logic and database service This will provide service
ability to the client even if one of the servers have
failed. Thus by deploying Network  Load
Balancing across a front-end Web server farm (Fig
1.), and clustering back-end line-of-business applications,
with application / business logic on one server (Node
1 in Fig.2) and database on another server (Node 2
in Fig.2), we will get the benefits of near-linear
scalability with no server or application-based single
points of failure. Ref: www.microsoft.com
Devendra Ozarkar, MTS, He is presently working
as a System, Network and Database Administrator for
the Pune Telecom, FACET and Telemedicine Project.
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