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John Paul Cook

Running SQL Server 2008 in a Hyper-V Environment

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SQL Server 2008 does perform very well in a Hyper-V environment when properly configured, which among other things means don't use the default of dynamically expanding virtual hard disk. Hyper-V isn't at all like Virtual Server or Virtual PC. It's best to drop preconceptions drawn from experience with those products.

For best I/O performance in Hyper-V, use passthrough disks (this is when a physical disk is assigned directly to Hyper-V without using a vhd file). Fixed size virtual hard disks are a close second. Dynamically expanding disks and differencing disks provide convenience at the cost of performance and thus should not be used when I/O performance must be maximized.

High network traffic imposes a burden on the CPU when running on Hyper-V (this is also true of Virtual Server). If a SQL Server configuration is CPU bound on bare metal, it might not have enough CPU cycles left for optimal networking performance. Also, keep in mind that a maximum of four logical processors can be assigned to a Hyper-V virtual machine, so if your SQL Server configuration needs more than four processors, it is not suitable for Hyper-V.

Published Monday, October 06, 2008 8:50 AM by John Paul Cook

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About John Paul Cook

John Paul Cook is a Data Platform Solution Architect working out of Microsoft's Houston office. Prior to joining Microsoft, he was a SQL Server MVP. He is experienced in SQL Server and Oracle database application design, development, and implementation. He has spoken at many conferences including Microsoft TechEd and the SQL PASS Summit. He has worked in oil and gas, financial, manufacturing, and healthcare industries. John is also a Registered Nurse who graduated from Vanderbilt University with a Master of Science in Nursing Informatics and is an active member of the Sigma Theta Tau nursing honor society. He volunteers as a nurse at a clinic that treats low income and uninsured patients. Contributing author to SQL Server MVP Deep Dives and SQL Server MVP Deep Dives Volume 2. Opinions expressed in John's blog are strictly his own and do not represent Microsoft in any way.

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