A flash cache is often used in tandem with slower hard disk drives (HDDs) to improve data access times. The form factor of the NAND flash is typically a solid-state drive (SSD) or a PCI Express (PCIe) card. In a common scenario, the system stores a temporary copy of the most active data in the flash cache and a permanent copy of the data on an HDD. When a data request is made, the flash cache serves the data, if a copy of it is available in the cache.
Flash cache can be located in the server, storage or network, and there are multiple ways to implement it. There are two main types of cache: read and read/write. Cache requires a warm-up time to populate it, and as more data enters the cache, more requests can be accelerated.
Numerous commercial offerings incorporate the term "flash cache" into their product names.