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Microsoft Load Balancing and
Clustering
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Outline
Introduction
Load balancing
Clustering
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Introduction
Server cluster is used to provide failover supportfor applications and services.
A Server cluster can consist of several nodes(computers).
Each node is attached to one or more clusterstorage devices.
Cluster storage devices allow different servers toshare the same data, and by reading this dataprovide failover for resources.
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Introduction
Load balancing is used to scale the system
as the client requests are increased
It is suitable for static data which can be
copied to several load balancing servers
Each server is autonomous which means
they dont share any state information
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Cluster Farm
A farm is a group of servers that run similarservices, but do not typically share data.
They are called a farm because they handle
whatever requests are passed out to them usingidentical copies of data that is stored locally.
Because they use identical copies of data (ratherthan sharing data), members of a farm operate
autonomously and are also referred to as clones. Front-end Web servers running Internet
Information Services (IIS) and using NLB are anexample of a farm.
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Cluster Pack
A pack is a group of servers that operate together and share partitioneddata.
They are called a pack because they work together to manage andmaintain services.
Because members of a pack share access to partitioned data, they haveunique operations modes and usually access the shared data on disk
drives to which all members of the pack are connected. An example of a pack is a database Server cluster running SQL Server
2000 and a server cluster with partitioned database views. Members ofthe pack share access to the data and have a unique chunk of data orlogic that they handle, rather than handling all data requests.
In a 4-node SQL Server cluster: Database Server 1 may handle accounts that begin with A-F. Database Server 2 may handle accounts that begin with G-M.
Database Server 3 may handle accounts that begin with N-S.
Database Server 4 may handle accounts that begin with T-Z.
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Server configurations
Server clusters can be setup using many different
configurations.
Servers can be either active or passive, anddifferent servers can be configured to take over the
failed resources of another server.
Failover can take several minutes, depending on
the configuration and the application being used,
but is designed to be transparent to the end-user.
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ClientsWindows Clustering
The Big Picture
IIS Web Serveror other IP based services
Network Load
Balancing
1
2
32
3
4
Data ServersSQL, Exchange, File
Cluster Service
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Clusteringmore detailed picture
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Windows Clustering:Addressing Concerns
Scalability
Scale Up
Scale Out
High Availability
99.9% Uptime
Manageability
Remote
UI and Command line
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Windows ClusteringVocabulary
MSCSServer clusters provide failover of resourcesrepresenting services, applications and base system
features between the servers in the Cluster.
NLB(WLBS) Network Load Balancing clustersdistribute client requests or TCP/IP network traffic
among many servers in the Cluster.
ClusterA group of independent computers that
work together to run a common set of applicationsand provide the image of a single system to the client
and application.
Nodes or HostsEach system in a cluster
confi uration.
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Server ClustersPhysical design
Client PCs
Public network
Private network(heartbeats, status, control)
RAID disk sets
Multi-initiator SCSI orSCSI over Fibre Channel
Cluster servers
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Server ClustersRecommended Environments
Microsoft SQL Server 6.5 & 7.0
Microsoft Exchange 5.5
File shares
Printer shares
Other cluster-aware applications & services
Typical uses are for data that changes
frequently and cannot be easily replicated.
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NLB HostNLB Host
NLB VirtualIP Address
NLB Host NLB Host NLB Host
Internet/
intranet
Network Load BalancingLogical Design
No single point offailure
No performance
bottleneck
No additional hardware
needed
Grow incrementally as
demand increases
Up to 32 nodes in a
cluster
Handle both planned and unplanned server downtime
transparently
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Configuring NLB with two network
adapters 1. Assign appropriate IP addresses to each NIC, placing the NICs in separate
subnets. Rename the first NIC Public and the second to NLB, do this foreach machine.
* Node1
o "Public" NIC* IP address: 10.10.10.11* Subnet: 255.255.255.0* Gateway: 10.10.10.1* DNS: as appropriate
o "NLB" NIC* IP address: 192.168.1.1* Subnet: 255.255.255.0* Gateway: N/A* DNS: N/A
2. On the "Public" NICs, click "Advanced" and add an additional IP address
as the Virtual IP Address which clients will connect to from the Publicnetwork (i.e. - 10.10.10.169)
Node2 -
o "Public" NIC
* IP address: 10.10.10.12
* Subnet: 255.255.255.0
* Gateway: 10.10.10.1
* DNS: as appropriate
o "NLB" NIC
* IP address: 192.168.1.2
* Subnet: 255.255.255.0
* Gateway: N/A
* DNS: N/A
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Infrastructure Scaling
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Clustering on different Windows
versions
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Architecting Multi-node Clusters
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Multiple Sites and Geographically
Dispersed Clusters
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Cluster models
Single node server clusters can be configured with, orwithout, external cluster storage devices. For single nodeclusters without an external cluster storage device, thelocal disk is configured as the cluster storage device.
Single quorum device server clusters have two or morenodes and are configured so that every node is attached toone or more cluster storage devices. The clusterconfiguration data is stored on a single cluster storagedevice.
Majority node set server clusters have two or more nodesbut the nodes may or may not be attached to one or morecluster storage devices. The cluster configuration data isstored on multiple disks across the cluster and the Clusterservice makes sure that this data is kept consistent across
the different disks.
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Cluster application types
Cluster-unaware applications. These types of applications do notinteract with the server cluster at all but can still fail over. Failuredetection is limited. The Cluster service protects these applicationsmainly against hardware failures.
Cluster-aware applications. These types of applications arecharacterized by superior failure detection. The Cluster service canprotect these applications not only against hardware but also againstsoftware failures.
Cluster management applications. These types of applications, whichinclude Cluster Administrator and Cluster.exe, allow administrators tomanage and configure clusters.
Custom resource types. Resource types provide customized clustermanagement and instrumentation for applications, services, anddevices.
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Server cluster components
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References
Microsoft.com