SQL Server 2012 AlwaysOn--Network card performance optimization in synchronous mode

This article is based on the previous "SQL Server 2012 alwayson--specified data synchronization link, eliminate network jitter caused by the submission delay problem" problem continue to optimize, the specific background please refer to the above;

After one months of tossing and turning, the hard-to-chew bone has finally been fixed. The problem is only the advanced function of the network card;

Solution: Turn off advanced features of the NIC Jumbo MTU and large Send offload V2

Problem analysis: Based on Broadcom Ethernet network adapter explanation

Jumbo Mtu

The Jumbo Mtu property allows the network adapter to send and receive jumbo Ethernet frames that are longer than 1514 bytes long but less than 9000 bytes. This property requires a switch capable of handling Jumbo frames.

By default, the frame size is set to 1500 bytes. To increase the size of the receive frame, you can increase the number of bytes by 500-byte increments.

Large Send Offload

TCP fragmentation is usually done by the protocol stack. When the Large Send offload property is enabled, TCP fragmentation can be done by the network adapter.

Disable: Disables Large Send offload.

Enable (default): Enables Large Send offload.

The Large Send offload is one of the advanced features of the network adapter, which is designed to reduce the pressure on the CPU and other related devices by segmenting TCP on the network adapter side, but with the wide application of multicore CPUs, the network adapter has a much weaker processing power than the CPU. Therefore, when a large number of concurrent requests result in frequent data updates or large data transfers, opening the large Send offload will severely affect performance;

Search on the Internet, the impact of such problems are more common

Http://www.bitdefender.com/support/Large-Send-Offload-causes-performance-and-slowdown-issues-459.html

http://www.peerwisdom.org/2013/04/03/large-send-offload-and-network-performance/

https://social.technet.microsoft.com/Forums/windowsserver/en-US/bdc40358-45c8-4c4b-883b-a695f382e01a/ Very-slow-network-performance-with-intel-nic-when-tcp-large-send-offload-is-enabled

is the performance curve before optimization, the figure shows the method call TP99 indicator jitter between 100~300ms

is the optimized performance curve, can see the optimized method call TP99 indicator in the 100~150ms range, and relatively stable;

Although WSFC no longer has a heartbeat line like Windows cluster, in order to avoid the impact of large data synchronization on the application access link, it is recommended to increase the direct line (or dedicated data synchronization network) and modify the Endpoint_url to take effect, depending on the SQL Server 2012 alwayson--Specifies a data synchronization link to eliminate commit latency issues caused by network jitter operations;

SQL Server 2012 AlwaysOn--Network card performance optimization in synchronous mode