SQL Server Performance

Long Distance Mirroring

Discussion in 'SQL Server 2005 Database Mirroring' started by cdykes, Apr 12, 2007.

  1. cdykes New Member

    I need to set up some sort of high availability solution from a data center in Virginia to a data center in Texas. Seems like mirroring is probably the way to go rather than transact replication. Can someone comment on the type of performance hit that would be seen over this distance using transaction safety set to full? I'm assuming that it's not even worth trying and that the only possible mirroring solution that is reasonable would be high performance. What type of data loss is possible with high performance? I understand that if the principal goes down and some of the very recently entered transactions have not made it to the mirror server, they will be lost.

    Assuming both servers are up and running smoothly, but the network is just bogged down, would there be a possibility of losing random data throughout the day or is it good at queing up the transactions that need to be committed to the mirror? Also, what if the mirrored server goes down temporarily or is rebooted...does it catch back up when it comes back?

    Thanks,
    Chris
  2. MohammedU New Member

    You should be very careful when you do the mirroring from VA to TX and I don't think it is advisable to run with SAFETY FULL mode... unless you have fat dedicated connectionn between the two centeres...
    Based on the distance check for log shipping or any other DR solution...

    If you run in full safety mode, it has to commit the trasansaction on primary as well as mirrored server which will effect performance...

    Database Mirroring Best Practices and Performance Considerations
    http://www.microsoft.com/technet/prodtechnol/sql/2005/technologies/dbm_best_pract.mspx



    MohammedU.
    Moderator
    SQL-Server-Performance.com

    All postings are provided “AS IS” with no warranties for accuracy.
  3. satya Moderator

    FOr such WAN based setup it is better to chop down the network issues or atleast to see a dedicated link is associated between principal and mirror servers, you can check my presentationhttp://sqlserver-qa.net/blogs/bc/ar...rroring-by-ssqa-in-sql-server-open-world.aspx with regard to using the database mirroring.

    Satya SKJ
    Microsoft SQL Server MVP
    Writer, Contributing Editor & Moderator
    http://www.SQL-Server-Performance.Com
    This posting is provided AS IS with no rights for the sake of knowledge sharing. The greatest discovery of my generation is that a human being can alter his life by altering his attitudes of mind.
  4. cdykes New Member

    thanks for the info. Did a lot of reading up this weekend. Haven't seen anything regarding licensing though. If I'm running 4 procs with standard on the principal, and the mirror is 4 procs, do I need 8 standard licenses, or does the 4 cover it since they are never both up at the same time?

    Thanks!!
  5. satya Moderator

    SQL server 2005 is based on the processor licenses, depending upon the count you have its best to consult a local Microsoft shop in this case.

    Satya SKJ
    Microsoft SQL Server MVP
    Writer, Contributing Editor & Moderator
    http://www.SQL-Server-Performance.Com
    This posting is provided AS IS with no rights for the sake of knowledge sharing. The greatest discovery of my generation is that a human being can alter his life by altering his attitudes of mind.

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