AlwaysOn sometimes becomes out of sync

  • OK im getting mixed messages on whether a heartbeat network is needed, Microsoft recommend you dont use one for 2008 onwards as it can have adverse effects. I can get another VLAN created and add another NIC to the servers but if Microsoft say it isnt needed then why bother? Surely a 10GB interface should be able to handle a simple heartbeat between nodes?

  • michael.mcloughlin (2/3/2014)


    OK im getting mixed messages on whether a heartbeat network is needed, Microsoft recommend you dont use one for 2008 onwards as it can have adverse effects.

    A lot changed in Windows 2008, Teamed adapter support was better as well as the improvements to the heartbeat networking. This post gives excellent detail of the changes.

    The detail in the link above mentions the special virtual heartbeat adapter which uses an APIP address, thing is it will have to bind itself to a NIC on the server to be able to complete the heartbeat communication.

    michael.mcloughlin (2/3/2014)


    Surely a 10GB interface should be able to handle a simple heartbeat between nodes?

    Yes but this 10Gbps connection is shared by however many VMs are connecting through the vSwitch, or are you saying that this VM is the only VM communicating through that switch?

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

  • Currently there are only these nodes with 10GBPs interfaces on this vSwitch. Any other VMs on the same vSwitch have 1Gbps nics configured. I will take a look at the URl you gave later, currently sorting a failed disk in the san 😎

  • what version ESX\VSphere you using?

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

  • Hi gurus !!

    Check if you have any error in the SQL Server Errologs related with avaliable workers and raise the value in case you find this error.

    How many databases you have using AlwaysON ? I plan tor prepare an 5000 databases AlwaysOn setup and my first tests ended with a bad result due a lack of threads. I increased the maximum workers value and it didn't help. Any of you have any experience with this amount of databases ? My understand is that it won't work with the hardware I have avaliable ( Two 16 corees 65 Gb of RAM ).

    Check this table (The number of workers might vary depending the number of cores you have).

    http://msdn.microsoft.com/en-us/library/ms190219.aspx

  • Perry Whittle (2/4/2014)


    what version ESX\VSphere you using?

    vSphere 5.5

  • jvazquezm (2/4/2014)


    Hi gurus !!

    Check if you have any error in the SQL Server Errologs related with avaliable workers and raise the value in case you find this error.

    How many databases you have using AlwaysON ? I plan tor prepare an 5000 databases AlwaysOn setup and my first tests ended with a bad result due a lack of threads. I increased the maximum workers value and it didn't help. Any of you have any experience with this amount of databases ? My understand is that it won't work with the hardware I have avaliable ( Two 16 corees 65 Gb of RAM ).

    Check this table (The number of workers might vary depending the number of cores you have).

    http://msdn.microsoft.com/en-us/library/ms190219.aspx

    Please open a new thread for this statement/question.

    But I will say that you will have an EXCEPTIONALLY hard time doing mirroring for that number of databases. It would lock up a ton of threads and hammer most IO subsystems. I once had a client that I managed to get up to 7400+ databases on a single server and I had to jump through all kinds of hoops to interact with and manage that server, including building a custom log shipping construct. All normal processes and tools just rolled over and died on the metadata (or worse took the server down with them).

    Best,
    Kevin G. Boles
    SQL Server Consultant
    SQL MVP 2007-2012
    TheSQLGuru on googles mail service

  • Thank you for your comment a will open a new thread with this topic. In this momment I have a lab with 4000 databases with only 1000 configured in two avaliability groups and the result is very disapointing. But I will explain it better in my own thread.

  • Please Private Message me when you make your new thread, I don't want to miss it! Thanks!

    Best,
    Kevin G. Boles
    SQL Server Consultant
    SQL MVP 2007-2012
    TheSQLGuru on googles mail service

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