My current lab consists of a single Hewlett Packard Proliant DL380 G6.
The hardware specifications are:
Model: ProLiant DL380 G6 Processor Type: Intel(R) Xeon(R) CPU X5560 @ 2.80GHz Logical Processors: 16 NICs: 4 Memory: 60GiB Storage: 2X Samsung evo SSD in raid0: 220GiB 1X Samsung HD103SJ: 915GiB On this i have installed:
VMware ESXi, 6.5.0
VMware vCenter 6.5.0
I am also running a windows server 2012 R2 server which takes care of ldap authentication (Active Directory) and DNS.