Sync Very Slow when more than 10 connections to SQL Server RRS feed

  • Question

  • Hi

    We are doing syncing from a SQL Server DB to a SQL Compact .sdf using the Sync Framework.

    One way syncing from the server to the client using wcf.

    I based my sync service app on the "WebSharingAppDemo-SqlProviderEndToEnd" example, using "KnowledgeSyncProvider" as my provider.


    At approximately 50 connections, data transfer to clients becomes extremely slow to non-existant (spikes of 3-5KB every 1-2 minutes, otherwise no data transfer occurs. Clients remains connected (determined using NETSTAT)).

    Problem doesn’t exist when <5 clients connected, then transfer to client is continuous.

    We using SQL Server 2008.


    Server Specs:

    Virtualised server

    Intel Xeon 2.67GHz (2xcores)

    4GB RAM

    Windows Server 2008 R2 Standard SP1

    SQL Server 2008 R2

    SQL Server Compact 3.5

    Sync Framework 2.1

    .NET 4.0

    100Mb internet connection (confirmed 60Mb/s transfer)


    What are we doing wrong?

    Can anybody help please.




    Wednesday, November 23, 2011 6:48 AM

All replies

  • enable Sync Tracing so you get to see where it's spending most of its time.

    On you Sql Server, use Activity Monitor to check if there's blocking...

    you didnt mention how many rows are you trying to sync per client, if you have filtering, and how big are the tables...
    • Edited by JuneT Wednesday, November 23, 2011 7:20 AM
    Wednesday, November 23, 2011 7:19 AM
  • Try to sync 16 tables.

    12 905 records in all the tables.

    The biggest table got 2829 rows.

    The smallest table got 65 rows.

    The affected tables has no filters.

    Wednesday, November 23, 2011 7:38 AM
  • you may want to trace the WCF service as well and check how you configured WCF to handle multiple concurrent connections. (check maxConcurrentCalls, maxConcurrentSessions)

    if you only have that much rows only and its a download only scenario, then it may be unlikely that its the SQL server that's the bottleneck (but monitor it just the same)

    • Edited by JuneT Wednesday, November 23, 2011 8:05 AM
    Wednesday, November 23, 2011 7:49 AM