IDE hard disk is out of date, SCSI hard disk is mainly used in servers, and it can still be seen in some older servers. NAS, SAS and even PCIE SSD are mostly used as hard disks for new servers.

SATA hard disk is still one of the mainstream consumer hard disks. SATA is subdivided into three versions according to the data transmission standard: SATA, SATA2 and SATA3, and the interfaces are compatible with each other. The theoretical maximum data transmission speed of SATA3 interface can reach 6 GB/s..

NVMe is a technical protocol adopted by solid state hard disk now. SSD supporting this protocol uses PCIE high-speed channel (bus) for data transmission. The theoretical speed can reach 32G version bps, which is close to 4GB/S in the four-channel PCIE3.0 mode, which greatly exceeds the SATA interface. On the physical interface, besides PCIE slot, there are M.2 and U.2 SSD interfaces with PCIE channel. M.2 interface is the most common in the field of consumer-grade solid-state drives, while U.2 is mainly used for enterprise-grade server solid-state drives. It should be noted that M.2 is just a physical interface or slot, which can support both PCIE channel and SATA channel, depending on the design of computer motherboard and solid state drive.