I'm trying to get a greater understanding around load balancing for Windows IIS Web servers and MSSQL database servers.

In our environment I have 2x IIS web servers and 2x MSSQL database servers. I am planning to put a fault tolerant ACE appliance for the web servers which connect to a shared database.

MSSQL db is mirrored to another server so if one of the db servers is down it automatically fails over to the 2nd server.

To fully load balance and keep high availability would I have to implement an MSSQL cluster? If you load balance the web servers, what considerations must be made for the database servers?


There are probably other ways to do it, but the best way in my opinion would be the MSSQL cluster for the database portion. Typically a load balanced set of web servers are ignorant to the database clustering, but that can change depending on your application. Most applications have individual discrete calls for data, so there's never any worry about being connected to a different database server, as long as the same dataset exists.

When you say the databases are mirrored, exactly how are they mirrored? An easier, common setup is to actually just have a shared datastore that fails over with the cluster. This probably isn't as fault tolerant as some mirrored options, but mirroring enters more variables. (How frequent is it mirrored, what's the load generated from constant mirroring, etc)

  • It is set up as High Safety with Automatic Failover (Synchronous) with a witness server. – Rowell Nov 11 '11 at 4:58

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