{"id":13232,"date":"2012-08-10T09:00:00","date_gmt":"2012-08-10T08:00:00","guid":{"rendered":"https:\/\/aidanfinn.com\/?p=13232"},"modified":"2012-08-10T09:00:00","modified_gmt":"2012-08-10T08:00:00","slug":"ws2012-hyper-v-advanced-storage-networking-performance-io-balancer-controls","status":"publish","type":"post","link":"https:\/\/aidanfinn.com\/?p=13232","title":{"rendered":"WS2012 Hyper-V \u2013 Advanced Storage & Networking Performance I\/O Balancer Controls"},"content":{"rendered":"

The <\/em>Performance Tuning Guidelines for Windows Server 2012<\/em><\/a> document is available and I\u2019m reviewing and commenting on notable text in it.<\/em><\/p>\n

These are very<\/em> advanced controls and should not be touched without reasonable consideration, planning, and understanding.  Don\u2019t go assuming anything, or playing with this stuff in a production environment.  Don\u2019t blame the settings if it all goes wrong, go look in a mirror instead.  Ok, that\u2019s the formalities out of the way.<\/p>\n

Microsoft says that:<\/p>\n

\n

The virtualization stack balances storage I\/O streams from different virtual machines so that each virtual machine has similar I\/O response times when the system\u2019s I\/O bandwidth is saturated<\/p>\n<\/blockquote>\n

When they talk about \u201cbandwidth\u201d they are talking about the ability to throughput data, e.g. networking or storage.<\/p>\n

We can manipulate the balance of that throughput in congestion scenarios, giving contending virtual machines a better shot at getting their network or storage throughput through the stack.  In other words, some VMs are hogging network\/storage IO and you want to give everyone a slice so they can work too.<\/p>\n

The registry controls for storage can be found at HKLMSystemCurrentControlSetServicesStorVsp.  The registry controls for networking can be found at HKLMSystemCurrentControlSetServicesVMSwitch.<\/p>\n

There are three REG_DWORD registry values to control I\/O balancing:<\/p>\n