A new policy setting has been introduced to accommodate the new RAID-5/RAID-6 configurations in VSAN (only available in All-Flash configuration). Minimum 4 hosts will be required for RAID5, and minimum 6 hosts will be required for RAID6 configuration.
This new policy setting is called Failure Tolerance Method. This policy setting takes two values: performance and capacity. When it is left at the default value of performance, objects continue to be deployed with a RAID-1/mirror configuration for the best performance. When the setting is changed to capacity, objects are now deployed with either a RAID-5 or RAID-6 configuration.
The RAID-5 or RAID-6 configuration is determined by the number of failures to tolerate setting. If this is set to 1, the configuration is RAID-5. If this is set to 2, then the configuration is a RAID-6.