VMware vSphere 5.1 vs. vSphere 5.5

vSphere 5.1 vSphere 5.5
Released September 2012 September 2013
Hypervisor ESXi ESXi
Physical CPUs per host 160 320
Physical RAM per host 2 TB 4 TB
vCPU per VM 64 64
vMEM per VM 1 TB 1 TB
VMDK Size 2TB 62 TB
VM Hardware Version 9 10
VMFS Version 5.58 5.60
Free ESXi Memory Limit 32 GB unlimited
Single Sign-On SSO 1.0 built on identity management by RSA SSO 5.5 completely rewritten from the ground up. Supports a multi-master model
vSphere Flash Read Cache NO YES
Virtual SAN NO YES
Reliable Memory Technology NO YES
vSphere Big Data Extensions NO YES
vSphere App HA NO YES
40GBps NIC Support NO YES
Windows 2012 Cluster Support NO YES
PDL AutoRemove NO YES
vSphere Replication Only one copy of a VM Up to 24 replicas
vCSA Scale (vPostgres) 5 Hosts
50 VMs
100 Hosts
3000 VMs