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High-Availability with Database Mirroring RRS feed

  • Question

  • We're looking into the SharePoint 2010 high-availability design depicted here:

    Configure availability by using SQL Server database mirroring (SharePoint Server 2010)
    http://technet.microsoft.com/en-us/library/dd207314.aspx.

    We are aware of the latency (=< 1 ms) and bandwidth (=> 1 Gbps) requirements and fulfill those.

    The question right now is about the required SQL Server 2008 R2 version: Enterprise or Standard Edition?

    The mirroring type is high-availability database mirroring, also known as high-safety mode with automatic failover (synchronous). My understanding is that this is fully supported by a combination of two SQL 2008 R2 Standard Edition servers plus one SQL Server 2008 Express Edition for the Witness server.

    SQL Server 2008 Mirroring in Standard Edition
    http://blogs.technet.com/b/andrew/archive/2008/11/04/sql-server-2008-mirroring-in-standard-edition.aspx

    Is this a correct understanding? Do we gain anything in terms of performance by moving to Enterprise Edition?

    Here it is stated: Standard Edition supports only single thread, synchronous only. Synchronous is the only option with a Witness server, but what does single thread mean in this context?

    Features Supported by the Editions of SQL Server 2008 R2
    http://msdn.microsoft.com/en-us/library/cc645993.aspx


    MCTS: Messaging | MCSE: S+M
    Sunday, October 30, 2011 11:07 AM

Answers

  • The single thread means
    http://social.msdn.microsoft.com/Forums/en-US/sqldatabasemirroring/thread/a5b58253-cf4a-4dd6-9472-c484347d39ab/

    The single thread mentioned refers to that only one thread will be used by theREDO queue of database mirroring system in Std edition . But in Enterprise edition , it follows the formula Redo threads = FLOOR ((number of logical processors +3) / 4) . Synchronous mode - SAFETY is always set to FULL ( Transactions gets committed at both the partners simultaneously)

    Synchronous mode is high-safety mode. There are more options with Enterprise edition one of them is high-performance, which is used mainly with geo-clusters.


    Marek Chmel, WBI Systems (MCTS, MCITP, MCT, CCNA)
    Sunday, October 30, 2011 2:11 PM

All replies

  • The single thread means
    http://social.msdn.microsoft.com/Forums/en-US/sqldatabasemirroring/thread/a5b58253-cf4a-4dd6-9472-c484347d39ab/

    The single thread mentioned refers to that only one thread will be used by theREDO queue of database mirroring system in Std edition . But in Enterprise edition , it follows the formula Redo threads = FLOOR ((number of logical processors +3) / 4) . Synchronous mode - SAFETY is always set to FULL ( Transactions gets committed at both the partners simultaneously)

    Synchronous mode is high-safety mode. There are more options with Enterprise edition one of them is high-performance, which is used mainly with geo-clusters.


    Marek Chmel, WBI Systems (MCTS, MCITP, MCT, CCNA)
    Sunday, October 30, 2011 2:11 PM
  • You may want to take a look at asynchronous mirroring.  It won't require 1ms/1gb as the transactions are committed to the owner prior to being sent to the partner.  But again, that is only in Enterprise.
    http://sharepoint.nauplius.net
    Sunday, October 30, 2011 5:13 PM
  • The single thread mentioned refers to that only one thread will be used by theREDO queue of database mirroring system in Std edition . But in Enterprise edition , it follows the formula Redo threads = FLOOR ((number of logical processors +3) / 4) . Synchronous mode - SAFETY is always set to FULL ( Transactions gets committed at both the partners simultaneously)

    Synchronous mode is high-safety mode. There are more options with Enterprise edition one of them is high-performance, which is used mainly with geo-clusters.


    Marek Chmel, WBI Systems (MCTS, MCITP, MCT, CCNA)

    Sorry, I did neither mean to mark nor unmark your answer (I'll come back to it a little bit later). However, it is close. Do you happen to know what this could mean in terms of performance for SharePoint?
    MCTS: Messaging | MCSE: S+M
    Monday, October 31, 2011 5:52 AM
  • You may want to take a look at asynchronous mirroring.  It won't require 1ms/1gb as the transactions are committed to the owner prior to being sent to the partner.  But again, that is only in Enterprise.
    http://sharepoint.nauplius.net

    Yes, but asynchronous mirroring does not support automatic failover. I'm actually not sure if all SharePoint databases that can be mirrored, support this mode. As stated above, we fulfill the network requirements for synchronous mirroring.

    Working mainly with Exchange 2010, I would very much have liked asynchronous mirroring with automatic failover. That's how it works within Database Availability Groups (DAGs).
    MCTS: Messaging | MCSE: S+M
    Monday, October 31, 2011 5:59 AM
  • This is a feature of AlwaysOn in SQL 2012 as far as i know.


    Marek Chmel, WBI Systems (MCTS, MCITP, MCT, CCNA)
    Monday, October 31, 2011 8:22 AM
  • Async Mirroring is a supported scenario for databases that support SQL Mirroring: http://technet.microsoft.com/en-us/library/ff628971.aspx#Section3
    http://sharepoint.nauplius.net
    Tuesday, November 1, 2011 4:43 AM