VMware vSAN can set availability, capacity, and performance policies per virtual machine. Table below shows an example of a storage policy on VMware vSAN.

Key storage policy rules: 

Storage Policy


Number of Failures to tolerate


Defines the number of host, disk, or network failures a virtual machine object can tolerate. For n failures tolerated, n+1 copies of the virtual machine object are created and 2n+1 hosts with storage are required. The settings applied to the virtual machines on the Virtual SAN datastore determines the datastore’s usable capacity

Object space reservation

Percentage of the object logical size that should be reserved during the object creation. The default value is 0 percent and the maximum value is 100 percent

Number of disk stripes per object

This policy defines how many physical disks across each copy of a storage object are striped. The default value is 1 and the maximum value is 12

Flash read cache reservation

Flash capacity reserved as read cache for the virtual machine object. Specified as a percentage of the logical size of the VMDK object. It is set to 0 percent by default and Virtual SAN dynamically allocates read cache to storage objects on demand

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