AlwaysOn AG replicating much slower than mirroring

  • I'm setting up AG replication over our WAN (1GB MPLS). Using sql stress, AG replication quickly falls behind. Network throughput plateaus at ~14Mbs.

    The problem ISN'T NETWORK

    using conventional mirroring, the same workload never falls behind, throughput plateaus at ~26Mbs.

    it's almost like log stream compression isn't happening for AG...

    both mirroring and AG are using async.

  • Did you make the secondary readable? If so, redo the AG without that and see if it makes a diff.

    Do you have static IPs or DHCP?

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

  • thanks for your response. the replica was initially read only, I later switched it to offline and it made no difference. All IPs on the cluster are static...

  • By "offline" I assume you meant "not readable".

    Well, those were my two items. I look forward to your finding and posting about a root cause. There are a few AG gurus here, hopefully they will chime in with some ideas.

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

  • DudeGuy (9/30/2014)


    I'm setting up AG replication over our WAN (1GB MPLS). Using sql stress, AG replication quickly falls behind. Network throughput plateaus at ~14Mbs.

    The problem ISN'T NETWORK

    using conventional mirroring, the same workload never falls behind, throughput plateaus at ~26Mbs.

    it's almost like log stream compression isn't happening for AG...

    both mirroring and AG are using async.

    Please confirm the status of the current cluster validation report

    -----------------------------------------------------------------------------------------------------------

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

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