On multiple engagements recently, I’ve worked with clients that didn’t include a whole lot of RAM in their new vSphere servers. For example, one bought new servers with 96 GB of RAM and another bought servers with 128 GB of RAM. The price differential to move to 256 GB of RAM was $1,000.
I strongly recommended to both clients that they consider at least 256 GB of RAM in all future server purchases. One of the goals of virtualization is to control costs through maximizing existing resources. It’s common to see vSphere environments operating at very low CPU levels even when they’re maxed out on RAM. As such, there are instances in which organizations are buying more servers just because they need more RAM. This adds both unnecessary hardware costs as well as new licensing costs.
My recommendation: Buy as much RAM as you can possibly afford for your virtual hosts. In the long-term, it will save money by enabling much higher virtual machine density on those hosts.