A server-based SSD is a solid state drive that may be manufactured in a PCI Express form factor. It could also be a SATA or SAS drive that plugs into the standard SATA/SAS interface, allowing it to be installed directly into a server.
Server-based SSDs can function as a cache in the server or as persistent storage, allowing the SSD server to have essentially an extremely fast scratch disk for very frequently accessed data. Putting this high performance storage directly in the server reduces latency because the server doesn’t have to access data on an external storage array. Because of this, server-based SSDs are high performance direct-attached storage. These SSD server drives are typically NAND flash-based.
Server-based SSDs are most often used for frequently accessed data in a database. Some examples of this are database indexes or whole databases. These best-use cases can reduce data access latency by as much as 90%. Both server vendors as well as some storage vendors offer server-based SSDs.