SQL Server Performance

database mirror - can the witness be protected from going down with disaster recovery?

Discussion in 'ALL SQL SERVER QUESTIONS' started by Trev256b, Oct 14, 2013.

  1. Trev256b Member

    i have database principle in data centre A, and database mirror in data centre B. if one of the data centres goes down how can i make sure the witness server stays online if it resides in one of the data centres?
    1) is there a simple way to replicate the function of the witness in another data centre, or do i just have to rebuild the witness in the other data centre?
    2) if the data centre goes down and the witness also goes down - does that mean the database mirror will not failover?
  2. Shehap MVP, MCTS, MCITP SQL Server

    In that case , I do prefer to put your witness server at a different site but if your haven’t enough room for another site, you shouldn’t worry much about data loss if you configured your DB Mirroring solution using synchronous mode to guarantee that each single transaction is saved on the principal server is committed as well on the mirror server but this can affect negatively on your database performance so you should take a conscious decision based on the nature of your system transitions workload , their frequency and their performance reads, in simple word your DB stress powers how far it can afford your users’ workload side by side with Synchronous mirroring

    Despite of this , if you have already SQL Server 2012 , you can make use of its new powerful technology HAG (High availability Always on group) to build a DR site without any data loss or performance impact in the same time using Asynchronous mode , you can read more about it at http://technet.microsoft.com/en-us/library/ff877931.aspx#AsyncCommitAvMode

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