Resolving NLB/CLB/MSCS Cluster Clusters

Microsoft servers offer three cluster-aware technologies: Network Load Balancing (NLB), Component Load Balancing (CLB), and Microsoft Cluster Service (MSCS).

Network Load Balancing (NLB, NetworkLoadBalancing)

Network Load Balancing acts as a front-end cluster for allocating incoming IP traffic in a server cluster, which is an incremental for e-commerce Web sites. Ideal for scalability and significant availability. Up to 32 Windows.NET Enterprise Servers can be linked together to share a single virtual IP address. NLB enhances scalability by allocating client requests across multiple servers within a cluster. As traffic increases, more servers can be added to the cluster, and any one cluster can hold up to 32 servers. NLB provides high-availability while providing continuous service to users, that is, automatically detecting server failures and reallocating client traffic among the remaining servers within 10 seconds.

NLB provides network traffic load balancing for TCP/IP-based services and applications to improve operating system availability and scalability. Common applications are terminalservice, webservice and webapplication. NLB provides external services through a virtual IP. When a request is received, NLB randomly determines which server will handle the request.

Component Load Balancing (CLB, ComponentLoActiveDirectoryBalancing)

Component Load Balancing distributes load across multiple servers running the site's business logic. It provides dynamic balancing of COM+ components in a server set with up to eight equivalent servers. In CLB, COM+ components are located on servers in separate COM+ clusters. The call to activate the COM+ component is balanced to the load of the different servers in the COM+ cluster. CLB works with NLB and cluster services by acting on the middle tier of a multi-tier cluster network. The CLB is provided as a feature of ApplicationCenter2000 and runs on the same set of computers as the Microsoft Cluster Service.

CLB primarily provides dynamic load balancing for mediation applications that use COM+ components to improve system availability and scalability. CLB will decide who will process the service request based on the current workload.

Cluster Service (MSCS, MicrosoftClusterService)

The Cluster Service acts as a back-end cluster that provides high availability for applications such as databases, messaging, and file and print services. When any node (the server in the cluster) fails or works offline, MSCS will try to minimize the impact of the failure on the system.

The Value of Cluster Services

Online business applications are at the heart of the company's operations, including databases, messaging servers, enterprise resource planning (ERP) applications, and core file/print services. The clustering service of the Windows 2000 operating system ensures that the above critical applications are online when needed by removing the physical server as a single point of failure.

When a hardware or software failure occurs on any node, the application currently running on that node is moved from the cluster service function to the other non-faulty node and restarted. Since the cluster service uses a shared disk configuration with a common bus structure such as SCSI and fiber, no data will be lost during a failure emergency.

MSCS mainly provides fault-tolerant transfer of back-end services and applications to improve system availability. Common applications are SQLServer and ExchangeServer.

MSCS is determined by the client to handle the service request, all servers share a sharetorage to store the session state. When the active server hangs, it continues to be taken over by the passive server. The passive server will take the session state from the sharestorage and continue the unfinished work to achieve the purpose of fault-tolerant transfer.

Cluster This cluster depends on which product, personally think that most of the cluster purpose is N nodes to share one or several common tasks. According to the function and structure, it can be divided into HA (High-availability High Availability Cluster) LB (Loadbalancing Load Balancing Cluster)

In the dual-system hot backup scheme, there are three different working modes according to the working mode of the two servers. That is, dual-system hot standby mode, dual-machine mutual standby mode, and dual-machine duplex mode.

Hot standby mode: the current active/standby mode, the active server is in working state; the standby server is in the monitoring preparation state, and the server data includes database data to two or more servers at the same time. Write (usually each server uses a RAID disk array card) to ensure instant synchronization of data. When the active server fails, the standby machine is activated by software diagnostics or manual mode to ensure that the application is fully restored to normal use in a short period of time. Typical applications are in securities funds servers or market servers. This is a mode that is currently used more, but since another server is in a backup state for a long time, there is a certain waste from the consideration of computing resources.

Two-machine mutual standby mode: two relatively independent applications run simultaneously on two machines, but each is set to be a standby machine. When one server fails, the other server can be short. The application of the faulty server is taken over in time, thus ensuring the continuity of the application, but the performance requirements of the server are relatively high. The configuration is relatively good.

Duplex mode: is currently cluster (cluster: cluster includes two, one is network load balancing, the other is server cluster. The duplex mode here is a network load balancing cluster In one form, both servers are active, running the same application at the same time, ensuring overall performance, load balancing and mutual backup, and the need to utilize disk storage technology (preferably in San mode). There are many such methods in the WEB server or FTP server.

Dual-system hot backup refers to hot standby (or high availability) based on two servers in a high-availability system. Because the two machines are highly available and used in China, it is named hot standby. Br>

Dual-system high-availability is divided into active-standby mode (Active-Standby mode) and dual-master mode (Active-Active mode). The active-standby mode refers to a server. In the active state of a certain service (that is, the Active state), another server is in the standby state of the service (that is, the Standby state). The dual-host mode means that two different services are in active/standby state (ie, Active-Standby and Standby-Active states) on two servers.

Load balancing, the English name is LoadBalance, which means that the load (work tasks) is balanced and distributed to multiple operating units for execution, such as Web servers, FTP servers, enterprise critical application servers and other key Task servers, etc., to work together to complete tasks.