what's new in vsphere 6 :- 

vSphere 6 ESXi and VM enhancements:

• Cluster now supports up to 64 nodes and 8.000 VMs
• VMs now support up to 128 vCPUs and 4 TB vRAM
• Hosts now support up to:
  480 pCPUs
  12 TB RAM
  datastores with 64 TB
  1000 VMs

Storage:

• Virtual Volumes (VVol)
• improved Storage IO Control

vSphere Fault Tolerance:

• FT support for up to 4 vCPUs and 64 GB RAM
• new, more scalable technology: fast check-pointing to keep primary and secondary in sync
• continuous availability – zero downtime, zero data loss for infrastructure failures
• FT now supports Snapshots (Backup)
• Storage Fault Tolerance:
  primary and secondary VM has its own .vmx & .vmdk files
  primary and secondary VM can be placed on different datastores!

vMotion Enhancements:

• vMotion across vCenter Servers
• vMotion across vSwitches
• Long-distance vMotion – now support of local, metro and cross-continental distances (up to 100+ms RTTs)

vCenter Server Appliance:

• the configuration maximums of the vCenter Server Appliance will be extended:
  The embedded DB now supports up to 1.000 Hosts and 10.000 powered on VMs (vSphere 5.5: 100 hosts/3000 VMs)

vSphere Web Client:

• long awaited performance improvements are implemented
• but nevertheless a Virtual Infrastructure Client 6.0 (C#) will be still available

Improved vSphere Replication:

• Recover Point Objectives (RPOs) will remain at 15 minutes (was at 5 min in early builds – maybe it will be higher in later releases)
• support for up to 2000 VM replications per vCenter

VMware Virtual SAN (VSAN 6.0)

• new On-Disk Format
• Performance Snapshots – vsanSparse
• usability improvements
• supports Failure Domains (note: failure domains are NOT metro/streched clusters)
• new disk serviceability feature

In vSphere 5.5 the maximum supported host memory was 4TB, in vSphere 6 that jumps up to 12TB. In vSphere 5.5 the maximum supported # of logical (physical) CPUs per host was 320 CPUs, in vSphere 6 that increases to 480 CPUs. Finally the maximum number of VMs per host increases from 512 in vSphere 5.5 to 1000 VMs per host in vSphere 6. While this is greatly increased I’m not sure there are many people brave enough to put that many VMs on a single host, imagine the fun of HA having to handle that many when a host fails.