FAQ : NLB & Clustering

Hmmm.. sudah waktunya mengkonfigurasi Network Load Ballancing & Clustering nih…. saya searching2 ini ada beberapa teori dasar dari forum2 luar nih… moga manfaat

ASK :

I have two servers running Windows 2008 Web Edition and SQL 2008 Standard Edition, how would be the best approach to load balance them?

Should I use database mirroring or log shipping? Is Win2008 NLB easy to configure by a developer, since I’m not a sys admin?

What I’m looking for is to be able to have my sites running in case of a single server malfunction, and also to be able to easily add more servers if the demand grows. My sites runs in ASP.Net 3.5 and all of them already store the session in SQL Server.

Answer :

Database clustering is a bit of an ambiguous term, some vendors consider a cluster having two or more servers share the same storage, some others call a cluster a set of replicated servers.

Replication defines the method by which a set of servers remain synchronized without having to share the storage being able to be geographically disperse, there are two main ways of going about it:

  • master-master (or multi-master) replication: Any server can update the database. It is usually taken care of by a different module within the database (or a whole different software running on top of them in some cases).Downside is that it is very hard to do well, and some systems lose ACID properties when in this mode of replication.

    Upside is that it is flexible and you can support the failure of any server while still having the database updated.

  • master-slave replication: There is only a single copy of authoritative data, which is the pushed to the slave servers.Downside is that it is less fault tolerant, if the master dies, there are no further changes in the slaves.

    Upside is that it is easier to do than multi-master and it usually preserve ACID properties.

Load balancing is a different concept, it consists distributing the queries sent to those servers so the load is as evenly distributed as possible. It is usually done at the application layer (or with a connection pool). The only direct relation between replication and load balancing is that you need some replication to be able to load balance, else you’d have a single server.

Windows Server 2008 Network load-balancing (NLB) explained

Network load-balancing (NLB)
Best for: Application Servers
Examples: Web Servers, VPN Servers, Exchange 2003 Front-end servers, Exchange 2007 CAS Servers

NLB provides a simple solution that allows high TCP/IP availability for application servers. NLB distribute the load among servers in the cluster group. When using NLB It is very important that Server OS and applications patch level are the identical to provide best user experience. You can install Server 2008 Network load-balancing (NLB) from Server Manager > “Add Features”.

Untuk cara setupnya ada disini :  http://technet.microsoft.com/en-us/library/cc754833(WS.10).aspx

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