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How to compress the data transfer during synchronisation between availability group nodes?

  • April 13, 2015 at 7:57 am

    #299754

    I got this situation where my network admin observerd that there is a high network utilization between 2 nodes in our AG (the primary node & the DR site, 2 separate locations of course); then he advised to compress the data transfer between those 2 nodes as the previous DBA already did that before!

    Ok, I have no clue about this, so decided to google it, got nothing, so any idea about that? would be great if you share it, thanx in advance.

    P.S: My backup is already compressed through some third party app (just in case if that matters to the subject).

    Hany Helmy

    Thanks & Best Regards,
    Hany Helmy
    SQL Server Database Consultant

  • April 14, 2015 at 2:53 am

    #1790695

    AlwaysON AG have built-in compression for the streams of transaction logs between the primary and secondary replicas, this is not an option that you can configure from within the AG.

    I know that log stream compression for Database mirroring was introduced in SQL Server 2008, and AG provides most of the functionality in DB mirroring plus it uses DB mirroring endpoints for transport - so compression is built-in. Research further around 'log stream compression'.

    Hope this helps

    --

    Charles

  • April 15, 2015 at 2:47 am

    #1791013

    From http://www.sqlserverspecialists.com/2013/02/log-stream-compression-sql-server-2008.html:

    [With SQL Server 2008 (I think the same applies to 2012), the log stream is compressed by default. To measure the impact of log compression, we used the trace flag 1462, which disables log compression].

    Checked the non-default configuration on the server, and this trace 1462 is not enabled, meaning the log is compressed already!

    Thanks & Best Regards,
    Hany Helmy
    SQL Server Database Consultant

  • April 15, 2015 at 5:04 am

    #1791044

    ideally you'd separate the mirror traffic down a separate connection to guarantee performance and security

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    "Ya can't make an omelette without breaking just a few eggs" 😉

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