When deploying random small IO-based database services on storage, which RAID type should be appropriate? for what?

Bank's bill imaging system often stores structured data on a SAN array, and unstructured data On the NAS array.

The data backed up by the differential backup is relative to the data added and modified after the last full backup.

The dual-controller storage system generally contains a mirror channel, and data written to the storage system cache will be written through the mirror channel Into the peer controller.

Which of the following is not a characteristic of the Cloud?