Push or Pull Replication

A study conducted by MSCOM ops team found 1 GB of data took 110 Minute to push and 12.5 minutes to Pull across the continents. Furthermore SQL 2008 with Windows Server 2008 made a huge difference over SQL 2005 and Windows Server 2003.


Push subscription replication of character data with SQL Server 2008 running on Windows Server 2008 yielded a 104 percent increase over SQL Server 2005 running on Windows Server 2003, and pull subscription replication of the same data yielded a 1,298 percent gain.


Lot of performance improvement is attributed to windows server TCP/IP Stack and SQL Native Client driver. Different reader and writer thread behavior resulted in push and pull performance difference.


Reader thread fills two buffers  of 40 KB  and signals the Writer thread to write the buffer on subscriber, so the 40 KB packet moves thru and fro over the wire, but in case of Pull model Writer thread pulls the data in one huge chunk as big as TCP/IP let it get.  One of the most significant improvements to Windows Server 2008 is the autotuning of the receive window size, designed for high-latency environments. In previous versions of the operating system, the maximum window size was limited by the 16-bit Window field in the TCP header amounting to a maximum window size of 64 KB. In Windows Server 2008, by combining the Window field together with a Scale Factor field of the TCP header, the window can be scaled or tuned, up to 16 megabytes (MB) in size.


Read the full study here http://msdn.microsoft.com/en-us/library/dd263442.aspx




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