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I'm about to study about NLB on Windows Server 2003. It archives both of my interests now: scalability and high-availability. But I don't know about its power in production environment.

  • Is NLB a efficient solution?

    How does it implement in real-world? Is it popular?

    What are its limit?

Thank you so much for answering my questions. :)

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up vote 4 down vote accepted

NLB is a decently efficient solution but it has it's limits, too. IT works single data center only, so you better make sure you dont have an issue there - or multiple NLB'd clusters. NLB scalability limits are in the documentation - I thin it is around 32 computers. It is a good solution if you dont have a front end load balancer (like in the router in front). It is definitely bettter than DNS round robin which on one side is ignorant to computer utilization and on the other hand of computers down for maintenace.

NLB will NOT solve inherent scalability issues, but it will try (and do a decent job) to balance incoming connections to the different computers.

Is it popular? Not SO much. The main reason being that many high end routers have load balancing functionality already in there, and somehow people go for hardware. Is it unpopular? No. Is it a shame it is not more widely used? Yes.It is really a decent technology.

Btw., upgrade to 2008 R2 - your license covers that anyway (unless you PURCHASED licenses, then you are - in for waste as they are not usable for service providers AND more expensive than the monthly SPLA rental agreeement with Microsoft.... a web server for around 15 USD per month processor license, btw.).

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Long waited for a proper answer. +1 vote. NLB seems to be not a preferred choice, is there some solutions that do better than NLB and are used widely on Windows platform? – Vimvq1987 Mar 20 '10 at 9:26
Not to my knowledge. THe main issue being that this is a rare scenario to start with - not many people see the need to develop something here. – TomTom Apr 20 '12 at 5:14

There are many many ways to achive NLB, it's not a one size fits all and really depends on what service and application your working with.

Scaling is key to many large internet applications. You may find this talk from the facebook engineers interesting.

It's sometimes more cost effective to use open source tools for clustering, per server licence fee's can cripple a startup. Don't even ask what a 2 million user client access licence will cost you ;-).

If you can identify where your bottlenecks are, you can concentrate on attacking these first for the greatest gains. No good scaling your front end http services, if all connections goto a overloaded and i/o bound mysql instance for example.

locked by splattne Mar 23 '10 at 19:05
Licensing costs - are only relevant for people who don't know about MS SPLA licenses. If the SPLA costs crippe a startup, it should not get on the market at all. Irrelevant answer with wrong information. – TomTom Mar 20 '10 at 8:56
@TomTom so your saying that licences costs on Windows is the same than hosting on FOSS? Please explain. Could you explain SPLA costs to me. How much would I pay for 30,000 users, 2xms-sql server, 2xiis servers. – The Unix Janitor Mar 20 '10 at 12:10
Not the same, but it makes simply no difference. FOSS since long time thinks the software cost is relevant - it is maintenance and upkeep of the infrastructure and the custom developped things that mkes the cost. Windows wont add more than 2 to 3% to the total cost. – TomTom Mar 20 '10 at 13:06
Pricing depdns on whether it is active/active or active/passive, but if you choose rightlicenses it is maybe 200 USD per month. NORMALLY. BizSpark gives you anything pretty much for free for the first years for a system that size - we talk of I think 100 USD for three years. But even 200 USD per month is nothing if you have 3-4 people to pay, servers to acutally lease, bandwidth to pay. And no - nr. of users is irrelevant, web licensing is always per processor. – TomTom Mar 20 '10 at 13:08
Licensing costs are a substantial consideration even for large projects. – Warner Mar 22 '10 at 14:42

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