DRS can manage virtual machines that have virtual flash reservations.
Virtual flash capacity appears as a statistic that is regularly reported from the host to the vSphere Client. Each time DRS runs, it uses the most recent capacity value reported.
You can configure one virtual flash resource per host. This means that during virtual machine power-on time, DRS does not need to select between different virtual flash resources on a given host.
DRS selects a host that has sufficient available virtual flash capacity to start the virtual machine. If DRS cannot satisfy the virtual flash reservation of a virtual machine, it cannot be powered-on. DRS treats a powered-on virtual machine with a virtual flash reservation as having a soft affinity with its current host. DRS will not recommend such a virtual machine for vMotion except for mandatory reasons, such as putting a host in maintenance mode, or to reduce the load on an over utilized host.