Server Virtualization. In the first phase of VMware server virtualization, older servers consuming two units of rack space were replaced with larger, more efficient servers consuming four units of rack space. Two tiers of virtual server infrastructure were defined. Tier 1 offered high availability and disaster recovery for critical applications; of the approximately 400 applications supported by EMC’s worldwide IT organization, this tier served about 20 mission critical applications (increasing to 27 at the end of each fiscal quarter to support peak needs). Tier 2, offering high availability only, was designed for the majority of applications that can.
