Intel Nehalem's Hidden Virtualization Risk
With advances in addressable memory, simultaneous multithreading and I/O handling, Intel's Nehalem microarchitecture allows IT managers to put even more VMs on a single physical system. But there is risk involved with putting too many virtual eggs in one physical basket, and data center managers must look to careful capacity planning, as well as monitoring and reporting tools, to prevent problems.Intel's Nehalem microarchitecture-now officially known as the Intel Xeon 5500 series-offers advances in addressable memory, simultaneous multithreading and I/O handling, providing IT managers with the ability to put even more virtual machines on a single physical system. But as memory capacity and compute power increase and I/O overhead diminishes, what's the new VM limit on a single system? The answer may be the amount of risk your organization can tolerate in terms of putting a large number of virtual eggs in one physical basket. To reduce risk, IT managers should place a premium on moving VMs to healthy physical systems and on data center management tools that monitor both the virtual and physical resources in the data center.
Several years ago, Intel introduced processor technology called FlexMigration that eases virtual-to-virtual machine movement across Intel processors of different generations. Combined with VMware's Extended VMotion-which overcomes limitations in the older, strict VMotion that required exactly matched physical processors-IT managers will have more options when it comes to migrating VMs. The trade-off is that VMs will be presented with a processor of the lowest-common-denominator feature set in the VMotion pool of physical systems.