The hard disk is the primary storage medium of the computer; the hard drive is equivalent to the computer’s warehouse, operating system, software, documents, data, etc. are stored in the form of data in the “warehouse.” That’s why hard drives are one of the essential pieces of hardware for a computer. So, what types of hard disk are there? Regarding the types of hard disk, there are two main classifications.
From the perspective of the hard disk interface, hard disk types are divided into IDE, SCSI, SAS, Fibre Channel, and SATA five kinds, IDE interface hard disk are mostly used in household products, but also partly used in servers; SCSI hard disk is mainly used in the server market; SAS that is, serial connection SCSI, is the new generation of SCSI technology; and Fibre Channel is only used in high-end servers, expensive; SATA is the more popular types of hard disk interface, is now the most popular interface type in the market.
From the perspective of the hard disk principle, the hard disk types are divided into SSD, HDD, SSHD.
Table of Contents
Classification by hard disk interface
IDE hard drive
IDE’s full name is “Integrated Drive Electronics,” which initially refers to a hard drive that integrates a “hard drive controller” with a “disk body.” The integration of the disk body with the controller reduces the number and length of cables at the hard disk interface, increases the reliability of data transfer, and makes hard disk manufacturing easier because hard disk manufacturers no longer need to worry about the compatibility of their hard disk with other manufacturers’ controllers.
The IDE interface technology has been in continuous development since its birth, and performance has been improving, and its low price, robust compatibility features, for which it has created other types of hard disk irreplaceable status.
IDE represents a type of hard disk, but in the actual application, people are also accustomed to using IDE to call the earliest appearance of IDE type hard disk ATA-1, this type of interface with the development of interface technology has been eliminated, and after the event of more types of hard disk interfaces, such as ATA, Ultra ATA, DMA, Ultra DMA, and other interfaces are IDE hard disk.
SCSI hard drive
SCSI is an entirely different interface from the IDE (ATA), which is the standard interface for ordinary PCs, while SCSI is not explicitly designed for hard drives.
SCSI has a wide range of applications, multi-tasking, large bandwidth, low CPU occupancy, and hot-swappable and other advantages, but the higher price makes it difficult to popularize as IDE hard disk, so SCSI hard disk is mainly used in mid- and high-end servers and high-end workstations.
Under the broad category of IDE and SCSI, a variety of specific interface types can be distinguished, each with a different specification. With varying speeds of transfer, such as ATA100 and SATA, Ultra160 SCSI and Ultra320 SCSI both represent a specific hard drive interface, and the respective rates vary widely.
SAS
SAS (Serial Attached SCSI) is the next generation of SCSI technology. Like the popular SATA (Serial ATA) drives, they use serial technology to achieve higher transfer speeds and improve internal space by shortening the connection lines.
SAS is a new interface developed after the parallel SCSI. This interface is designed to improve the performance, availability, and expandability of storage systems and to provide compatibility with SATA hard drives.
The SAS interface technology is backward compatible with SATA. Accurately, the compatibility of the two is mainly reflected in the physical and protocol layers.
Fibre Channel
The spelling of Fibre Channel is Fibre Channel, and SCIS interface like Fibre Channel was not originally designed and developed for hard disk interface technology, is specially designed for network systems, but with the storage system for speed requirements, only gradually applied to the hard disk system.
Fibre Channel hard drives were developed to increase the speed and flexibility of multi-drive storage systems, and their advent has dramatically increased the rate of communication in multi-drive networks. The main features of Fibre Channel are hot pluggability, high-speed bandwidth, remote connectivity, a large number of connected devices, etc.
Fibre Channel is designed to meet the high data transfer rate requirements of high-end workstations, servers, massive storage sub-networks, bi-directional, and serial data communication between peripherals through hubs, switches, and point-to-point connections in a multi-drive system environment such as servers.
SATA hard drive
In 2001, the Serial ATA Committee, composed of Intel, APT, Dell, IBM, Seagate, and Maxtor, formally established the Serial ATA 1.0 specification. In 2002, the Serial ATA Committee established the Serial ATA 2.0 specification, although Serial ATA-related equipment has not yet been officially launched.
The Serial ATA bus uses embedded clock signals to provide more robust error correction capability. The most significant difference is that the transmission commands can be checked, and errors will be corrected automatically if found, which significantly improves the reliability of data transmission.
Classification by principle
Hard drives can be classified into SSD, HDD, SSHD according to the principle
SSD
SSD’s are all known as Solid State Disks, which are arrays of multiple flash memory chips plus a master and cache, and are hard disks made from collections of solid-state electronic storage chips. It consists of no control unit and no storage unit. Solid-state drives are identical to ordinary hard drives in terms of interface specification and definition, function, and usage.
There are two kinds of solid-state hard disk storage media; one is to use flash memory as storage media, the other is to use DRAM as storage media, is widely used in military, automotive, industrial control, video surveillance, network monitoring, network terminals, etc.
The new generation of SSDs is universally available in mSATA, SATA, PCIe, M.2.
The mSATA interface, fully known as the mini SATA interface, can be thought of as the mini version of the standard SATA interface, while the physical interface is the same as the mini PCI-E interface.
The M.2 interface of the nvme protocol high-performance SSD is new in the last two years, about the size of two fingers, it is both sequential read/write speed, and 4K IPOS performance is more than two times higher than the SATA interface, the performance is more reliable.
SATA interface is currently the most used hard disk interface, SATA 3.0 interface is the most significant advantage of maturity.
The PCIe interface is a new generation of hard drive interfaces and compared to the SATA interface, and a PCI-E lane car is like driving on a highway, while a SATA lane car is like driving on a bumpy mountain road.
Advantages: fast reading and writing speed, anti-vibration and drop resistance, low power consumption, no noise, broad working temperature range, lightweight.
Disadvantages: small capacity; limited life; high price
HDD
The full name of HDD is Hard Disk Drive and is one of the primary storage media for computers. It consists of one or more magnetic discs made of aluminum or glass, magnetic head, spindle, control motor, head controller, data converter, interface, and cache. During operation, the magnetic head is suspended on a high-speed rotating disc to read and write data. The mechanical hard disk is a computer storage device that integrates precision machinery, microelectronic circuits, and electromagnetic conversion into one.
The pros: large capacity, meager price, and enough performance for the vast majority of people in the vast majority of situations.
Disadvantages: HDD storage media is a disk and contains a very complex and sophisticated mechanical structure, so it is terrified of vibration when running
SSHD
SSHD is a combination of mechanical hard disk and solid-state drive, using smaller capacity flash memory particles to store commonly used files. In contrast, the disc is the most critical storage medium, flash memory only serves as a buffer, saving the most widely used data into the flash memory to reduce the search time, thus improving efficiency.
SSHD is not as big as regular HDD, not as fast as SSD, and not as safe as enterprise drives at the same price. Yet only twice as expensive as different drives, being able to buy all three at the same time and never finding such a product again. It can be said that SSHD is both space and reading speed.
Pros: Hybrid drives take advantage of both mechanical and solid-state drives and are somewhere in between in terms of speed and are less expensive than solid-state drives.
Disadvantages: The combination of advantages also leads to a combination of problems, the hybrid hard disk like the mechanical hard disk is sparse for shock resistance. Like the solid-state hard disk, the number of flash memory particles in reading and writing has a corresponding limit; the good thing is that this flash memory only records the standard files, and only backup, rather than storing the data entirely in the flash memory.
Which one should you choose?
In the past ten years, CPU performance has increased by more than 150 times, while traditional mechanical hard drives have increased by less than 1.5 times, this uneven development, significantly affecting the overall performance improvement.
Compared to HDDs, SSDs do not have a series of components such as heads, motors, disks, etc., and are unmatched by traditional hard drives in terms of speed, power consumption, and lightness.
At present, traditional hard drives still occupy a significant share of the hard drive market because of low cost and other factors, however, as the cost of SSDs continues to decline, technology continues to improve, and better support for the system and other factors, the future to replace traditional hard drives is also an inevitable trend.
The above is a detailed explanation of the types of hard drives; we suggest that for those with an average budget, the best match is SSD+HDD, while those without budget constraints can choose SSD directly.