vSphere High Availability Enhancements (vSphere 6.0)

vSphere HA delivers the availability required by most applications running in virtual machines, independent of the OS and application running in it. It provides uniform, cost-effective failover protection against hardware and OS outages within a virtualized IT environment. It does this by monitoring vSphere hosts and virtual machines to detect hardware and guest OS failures. It restarts virtual machines on other vSphere hosts in the cluster without manual intervention when a server outage is detected, and it reduces application downtime by automatically restarting virtual machines upon detection of an OS failure.

With the growth in size and complexity of vSphere environments, the ability to prevent and recover from storage issues is more important than ever. vSphere HA now includes Virtual Machine Component Protection (VMCP), which provides enhanced protection from All Paths Down (APD) and Permanent Device Loss (PDL) conditions for block (FC, iSCSI, FCoE) and file storage (NFS).

Prior to vSphere 6.0, vSphere HA could not detect APD conditions and had limited ability to detect and remediate PDL conditions. When those conditions occurred, applications were impacted or unavailable longer and administrators had to help resolve the issue. vSphere VMCP detects APD and PDL conditions on connected storage, generates vCenter alarms, and automatically restarts impacted virtual machines on fully functional hosts. By doing this, it greatly improves the availability of virtual machines and applications without requiring more effort from administrators. 

vSphere HA can now protect as many as 64 ESXi hosts and 8,000 virtual machines—up from 32 and 4,000— which greatly increases the scale of vSphere HA supported environments. It also is fully compatible with VMware Virtual Volumes, VMware vSphere Network I/O Control, IPv6, VMware NSX™, and cross vCenter Server vSphere vMotion. vSphere HA can now be used in more and larger environments and with less concern for feature compatibility.

More details:-  http://www.vmware.com/files/pdf/vsphere/VMW-WP-vSPHR-Whats-New-6-0-PLTFRM.pdf