Driver: Interrupt Coalescing / Moderation Driver: Offloading (IP / TCP / UDP) offload engine for layer 3 or 4 protocols there is also a "Large Segment Offload" feature on some adapters. I have labeled my findings based on where you'll find it: either as an operating system feature, or in the device manager of the Ethernet adapter you're using. This is the start of a two-part series regarding tweaks I have found for networking in each type of system. The performance change increase for a SQL server is usually quite noticeable from some of the ones I have done in the past.Like most Sys Admins, my job includes managing both Linux and Windows machines. Multiple processors are a good thing for networking, not a bad thing.
Why VMware thought it was a BAD idea to “ DISABLE” the “ Receive Side Scaling“ parameter as a default on the VMXNet3 network card, I just can’t understand. Typically this outage lasts only 5 seconds maybe. Saving these changes will cause a slight outage for the VM server as it needs to reset the network card to read in the new configuration parameters. Maximum Number of RSS queues = 4 (This should match the “Maximum Number of RSS Processors” parameter.) Maximum Number of RSS processors = 4 (Depends on the number of Processors available on the server. Receive Side Scaling (RSS) = ENABLE (This setting is a very important performance parameter) Some parameters verbage may be slightly different depending on the version of the driver. In Windows, Edit the adapter and change the following parameters as shown in RED. The other change that needs to made and this is the important one, is on the VMWare VMXNet3 network card. I believe that has been resolved in a newer driver version. There was a bug in the VMWare VMXnet3 driver that caused performance issues for SQL server when the “RSC” parameter was enabled on the OS. The “Receive Segment Coalescing State”, ie “RSC”, parameter seems to do the most good especially when running SQL server. There is no outage required to change these OS parameters. I usually put these commands in a batch file or script when I need to execute them. In Windows, Open a command prompt window with elevated permissions and execute the following commands displayed in RED.Ĭ:> netsh int tcp set global chimney= disabledĬ:> netsh int tcp set global autotuninglevel= disabledĬ:> netsh int tcp set global ecncapability= disabledĬ:> netsh int tcp set global netdma= disabledĬ:> netsh int tcp set global rsc= disabled VMWare VM Server Tuning – Windows OS & VMXNet3 Network Card Optimizations
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