SQL Server Failover Solutions

  • Opinions please on the best failover solution for SQL Server.

    I am aware of a number of software packages that provide failover but I don't know what is the tried and trusted failover solution.  I am also aware of SQL Clustering and Log Shipping but have never used a failover before.

    Regards

     

    Carl

  • The "best" solution depends on a combination of your business requirements and your budget...

    Log shipping is sometimes seen as the "poor man's" solution, but that is far too simple.  Log shipping doesn't require a SAN like clustering, but it tends to require more care and feeding.  Also, failover in a log shipping environment is not automatic nor is it transparent to the application(s), unlike clustering.

    There are third part solutions that provide some additional benefits such as PolyServe, and I believe that SonaSoft has a failover product as well.  I'm not too familiar with the SonaSoft product but it looks primarily like an automation enhancement layer for log shipping.  PolyServe is more in the mold of clustering and requires a SAN.  PolyServe is something that we are looking into; if it performs as advertised, it is a very impressive product indeed.

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    If most people are not willing to see the difficulty, this is mainly because, consciously or unconsciously, they assume that it will be they who will settle these questions for the others, and because they are convinced of their own capacity to do this. -Friedrich August von Hayek

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  • This may be a stupid questions, but if log shipping and clustering are built into SQL Server, why would you purchase a 3rd Party App to accomplish that?  What are the advantages to buying the 3rd Party App?

    Thanks,

    Matt

  • In the case of PolyServe it's because the product brings totally new capabilities as well as provides some that are SIMILAR to clustering, but it does not use Windows Clustering per se.  MS clustering also requires the use of Enterprise Edition, PolyServe has no such requirement so it can provide failover without spending the big bucks on EE.  Granted, you have to shell out money for PolyServe, but in our case it is significantly less than EE. 

    Yes, I know that with SQL 2005, Standard Edition can be clustered, but it is limited to two nodes and even the Enterprise Edition capability lacks the flexibility and features of PolyServe.

    I don't want to be accused of being a PolyServe salesman, so I would just say that you should check it out for yourself, and decide whether the benefits outweigh the costs.

    /*****************

    If most people are not willing to see the difficulty, this is mainly because, consciously or unconsciously, they assume that it will be they who will settle these questions for the others, and because they are convinced of their own capacity to do this. -Friedrich August von Hayek

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