These types of solutions were usually targeted at enterprise customers who had heavy random read and write workloads that needed to be non-volatile. The disks u

These types of solutions were usually targeted at enterprise customers who had heavy random read and write workloads that needed to be non-volatile. The disks usually had a battery with enough life to dump the data to persistent storage in the case of a reboot or power outage. For example if you had need to continuously update a bloom filter for some reason. They have been mostly displaced by enterprise SSD based drives that have high IOPs or big data solutions with transaction logs and distributed reads and writes.