Once you've started procuring new hardware for the production infrastructure, you'll want to reference settings you've made in the lab to ensure that the virtual servers you plan to deploy will be able to handle the tasks assigned to them.
Furthermore, after you've completed the production build, you can use the lab to test new functionality, updates, and beyond, which will only bolster the stability and reliability of the production platform.
6. Use an Existing-Infrastructure Profiling Tool
Virtualization vendors offer several tools that can forecast what hardware you'll need to move a physical infrastructure into the virtual realm. These tools, such as VMware's Capacity Planner, require some setup and configuration, but can provide a wealth of extremely useful information before you spend a dime on production hardware.
These tools employ constant performance profiling to gauge the resources that each server on your network consumes, generally over a period of time from 30 to 60 days. They see the peak utilization of CPU, RAM, disk, and network I/O resources, and mix all of that data together to produce a guide to the CPU, RAM, storage, and network requirements you'll need to shift the infrastructure into the virtual world. In some cases you can even define the brand and model of the servers you're considering, and the tool will tell you how many you need. Playing with the numbers here can save you plenty of money down the road.
7. Spec and Purchase the Production Hardware
Based on the results from your lab testing and capacity planning, you should have a good idea as to what resources each of your physical host servers will require in production--at least to a point.
Spec out the servers to be identical units, from the CPU model to the amount of RAM present. In some instances it's much more financially sound to add another server than to add high RAM counts in a smaller number of servers: Since higher-density RAM is notably more costly than lower-density RAM, you may find that it's cheaper to purchase, for example, six servers with 32GB RAM each than three servers with 64GB RAM each. Buying a larger number of servers has the added benefit of broadening reliability, as you'll have more physical servers to take the load should a failure occur.
As far as storage goes, you'll get more bang for your buck with iSCSI or NFS storage than with Fibre-Channel at this point, especially in lower-scale projects. Regardless, make sure that your storage vendor is approved for use with the virtualization software you've chosen, and that you find some best-practices guides to tune your network, servers, and storage devices for optimal performance. In many cases tuning is as simple as enabling jumbo frames or using link aggregation protocols to increase the bandwidth available to the storage device.
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