What is a solid-state drive? What is a solid-state drive?

Solid-State drives (Solid state disk, or SSD) are external storage devices that are based on permanent storage, such as flash memory, or non permanent storage, such as synchronous dynamic random access memory (SDRAM). Solid-State drives are used to replace a regular hard disk in a portable computer. Although there is no disk-like mechanism to rotate on a solid-state drive, this type of memory is still known as a "hard disk" according to people's naming conventions.

Classification of solid-state drives

Based on non-permanent storage

Solid-State drives made of non permanent storage are used primarily for temporary storage. Because this kind of memory needs to rely on external power to maintain its memory, so the solid-state drive made by this will also need to match the battery to use. Non-permanent memory, such as SDRAM, has the characteristics of fast access. With this feature, the program that needs to be run can be copied from the regular hard drive to the solid state drive first, and then to the computer, to avoid the impact of the hard drive delay and the seek delay on the program performance.

In addition, solid-state drives made from non permanent storage are also used for emergency backups. This type of solid-state hard drive, which is powered by batteries, can have enough time to transfer data to a regular hard drive when the power supply is accidentally interrupted. When power is restored, the data is recovered from the regular hard drive.

Based on permanent memory

The data access speed of the permanent storage is between the non permanent memory and the regular hard disk. As opposed to permanent storage, permanent storage does not require external power to maintain its memory once it has been written to the data. It is therefore more suitable as a substitute for conventional hard disks.

Flash memory is the most common permanent storage. Small-capacity flash memory can be made into a mobile storage device with USB interface, which is often referred to as "USB drive". With the decrease of production cost, it is possible to integrate several large capacity flash modules into a solid-state hard disk with flash memory as storage medium.

The form of solid-state hard disk

As a substitute for conventional hard drives, solid-state drives are made in the same shape as regular hard disks, such as common 1.8-inch, 2.5-inch, or 3.5-inch specifications, and are compatible with each other.

The advantages of solid-state drives

Compared with conventional hard disk, flash memory has the characteristics of low power consumption, no noise, vibration and low heat. These features not only allow the data to be saved more securely, but also prolong the continuous running time of the battery-powered equipment.

For example, the Korean Samsung semiconductor Company (Samsung Semiconductor) launched in March 2006 a 32GB solid-state hard drive, using the same 1.8-inch specifications as the conventional micro-drive. Its power consumption is only 5% of the regular hard drive, the write speed is 1.5 times times the regular hard drive, the reading speed is 3 times times of the regular hard drive, and there is no noise.

In 2007 Computex SanDisk publishes 64GB and 32GB solid-state drives with 2.5-inch, SATA-interface and 1.8-inch, Uata-Interface specifications. A-data on-site solid state drives are divided into 2.5-inch and 1.8-inch two, of which 2.5-inch SATA interface, the maximum capacity of up to 128gb;1.8-inch machine is the IDE interface, the maximum capacity up to 64GB, can be used in the note-type brain and smaller UMPC, Used to replace the traditional hard drive.

Disadvantages of solid-state drives

Cost is the biggest problem that limits the popularity of solid-state drives. At present, the cost per million byte is much higher than that of a regular hard disk, whether it is a permanent or a non-persistent memory. So the price of a small, solid-state drive can be borne by most people.

Solid-state drives have traditionally been used only for military and industrial use because of their high prices, but thanks to the declining cost of NAND flash memory, solid-state drives are now expected to be used on a typical notebook computer to provide a new computer experience. Compared with traditional hard disk, SSD has the advantages of fast speed, low power consumption and high reliability. Because the hard disk is already the bottleneck of system efficiency, it can bring exciting performance improvement by changing the solid state drive.