Pretty sure it's that the various sizing calculators from Microsoft always base figures on physical/actual number of cores. When you introduce HT, you're not really giving yourself double the number of CPUs in raw performance, so any planning based on the calculators goes out the window.
We disable it on our servers, but only as the recommendation. Richard From: bounce-9546388-8066...@lyris.sunbelt-software.com [mailto:bounce-9546388-8066...@lyris.sunbelt-software.com] On Behalf Of Sean Martin Sent: 06 September 2012 00:33 To: MS-Exchange Admin Issues Subject: Exchange 2010 Design Questions Hello all, I'm a little more than a year removed from any real Exchange management but I am loosely involved with my company's re-vitalized effort to migrate from Exchange 2003 to Exchange 2010. We recently had an Exchange PFE onsite to assist with a high-level design for our environment. One of the recommendations kind of threw me for a loop and I wanted to get some feedback from those of you running Exchange 2010. Disable Hyper-threading - http://technet.microsoft.com/en-us/library/dd346699.aspx: The article states: "Hyperthreading causes capacity planning and monitoring challenges, and as a result, the expected gain in CPU overhead is likely not justified. Hyperthreading should be disabled by default for production Exchange servers and only enabled if absolutely necessary as a temporary measure to increase CPU capacity until additional hardware can be obtained." What capacity planning and monitoring challenges are introduced? We've been running hyper-threaded multi-core servers for many, many years and I can't think of any challenges that were introduced. Is there a specific scenario I'm not thinking about that is specific to Exchange capacity planning or monitoring? FWIW, we have 6 physical servers which will be evenly distributed between two active sites based on the latest design. Servers are Dell PowerEdge M610 blade servers with dual 6-core procs, 24GB memory, QLogic 8GB HBAs* connecting to Compellent Storage. *3 servers at one site will actually leverage infiniband (4x40GB) connectivity to Xsigo directors which will distribute vHBAs and vNICs. Any insight would be appreciated. - Sean --- To manage subscriptions click here: http://lyris.sunbelt-software.com/read/my_forums/ or send an email to listmana...@lyris.sunbeltsoftware.com<mailto:listmana...@lyris.sunbeltsoftware.com> with the body: unsubscribe exchangelist --- To manage subscriptions click here: http://lyris.sunbelt-software.com/read/my_forums/ or send an email to listmana...@lyris.sunbeltsoftware.com with the body: unsubscribe exchangelist
