SSD caching is a data processing technology which uses solid state drives as a buffer space for frequently used data. Read and write operations are faster, since the system detects "warmth" of the data and, if it is "hot" enough, puts it to high speed drives.
For instance, SSD cache significantly increases productivity when the storage is processing streams in video surveillance environment. This workload pattern receives mostly sequential requests with seldom random write and read operations. Without SSD cache, the storage makes attempts to moderate these peaks by HDDs, which consequently cause total performance degradation.