What Is a Solid State Drive?

A solid state drive (Solid State Disk or Solid State Drive, referred to as SSD) is commonly known as a solid state drive. A solid state drive is a hard disk made from an array of solid state electronic memory chips. It is named because Taiwanese English calls solid capacitors Solid. The SSD consists of a control unit and a storage unit (FLASH chip, DRAM chip). The specifications and definitions, functions, and usage methods of the solid-state hard disk are exactly the same as those of ordinary hard disks, and the shape and size of the product are completely the same as those of ordinary hard disks. It is widely used in military, vehicle, industrial control, video surveillance, network monitoring, network terminals, power, medical, aviation, navigation equipment and many other fields.

Classification:

In 1956,

based on

The interface specifications and definitions, functions and usage methods of solid-state hard disks are almost the same as those of ordinary hard disks, and their shape and size are basically the same as those of ordinary 2.5-inch hard disks.

Solid-state hard disks have the characteristics of fast reading and writing, light weight, low energy consumption, and small size that traditional mechanical hard disks do not have. At the same time, their disadvantages are also obvious. Although IDC believes that SSD has entered the mainstream of the storage market, its price is still relatively expensive, its capacity is low, and once the hardware is damaged, it is difficult to recover data, etc .; and some people think that the solid state hard disk has a relatively short durability (life).

Several factors that affect the performance of solid state drives are: the main control chip, NAND flash media, and firmware. Under the same conditions, the interface used may also affect the performance of the SSD.

The mainstream interfaces are SATA (including 3Gb / s and 6Gb / s) interfaces, and SSDs with PCIe 3.0 interfaces have also come out.

Due to the differences in the design and data reading and writing principles of SSDs and ordinary disks, the internal structure is also very different. Generally speaking, the structure of a solid state drive (SSD) is relatively simple and can be disassembled; therefore, most articles we read about SSD performance evaluation have attached the internal disassembly diagram of the SSD.

In contrast, the reading and writing of ordinary mechanical magnetic disks is based on the airflow generated by the high-speed rotation of the disk to hold the magnetic head, so that the magnetic head is infinitely close to the disk without contact, and the magnetic head is driven by the stepper motor to change the lane Data read. Therefore, its internal structure is relatively complicated and precise, and disassembly is generally not allowed. Once dismantled, it is very likely to cause damage and the disk will not work properly. This is why when we evaluate disks, we basically can't see the disk removal diagram. ^[4]

Fast reading and writing speed: using flash memory as the storage medium, the reading speed is faster than that of mechanical hard disks. Not used for SSD

Capacity: The maximum solid-state drive capacity is only 4TB. Optimus MAX (Optimus Prime) released by SanDisk ^[6]

For the use and maintenance of solid state drives, the most important one is that the "good habits" developed in the era of mechanical hard drives may not be suitable for solid state drives.

First, don't use defragmentation

Defragmentation is a good way to deal with the slowdown of mechanical hard disks, but it is totally a kind of "torture" for solid state drives.

There is a limit to the number of times a consumer solid state drive can be erased and written, and defragmentation will greatly reduce the life of the solid state drive. In fact, the solid state hard disk's garbage collection mechanism is already a good "disk defragmentation", no more defragmentation is completely unnecessary. Windows' "defragmentation" function is a product of the era of mechanical hard disks and is not suitable for SSDs.

In addition, it is best to disable win7's Superfetch and Windows Search functions when using solid-state drives. These two functions are not of practical significance, and disabling can reduce the hard disk read and write frequency.

Second, small partitions and less partitions

It is also due to the "garbage collection mechanism" of solid state drives. Deleting a file completely on a solid state hard disk is to destroy the entire area where the invalid data is located. The process is as follows: first gather the valid data in the area, move it to a free place, and then clear the "problem area".

This mechanism means that the SSD capacity should not be full when partitioning. For example, a 128G solid-state hard disk, the manufacturer will generally nominally 120G, a part of the space is reserved. However, if you only divide 100G when partitioning, leaving more space, the performance of the solid-state hard disk will be better. This reserved space is automatically used for optimization operations inside the SSD, such as wear leveling, garbage collection, and bad block mapping. This practice is called "small partition".

"Few partitions" is another concept related to the impact of "4k alignment" on solid state drives. On the one hand, the mainstream SSD capacity is not very large. More partitions means more wasted space. On the other hand, too many partitions easily lead to misalignment of partitions, and the performance of the disk area at the partition boundary may be affected. The easiest way to maintain "4k alignment" is to use the partitioning tool that comes with Win7 to partition, so that the divided areas are guaranteed to be 4K aligned.

Third, reserve enough free space

The more SSD storage, the slower the performance. And if a partition is in the state of more than 90% usage for a long time, the probability of a solid state drive crashing will be greatly increased.

Therefore, it is very important to clean up useless files in time, set an appropriate virtual memory size, and store large files such as movie music on a mechanical hard disk. You must allow sufficient free space on the solid-state hard disk partition.

Fourth, update the firmware in time

"Firmware" is like the BIOS on the motherboard, which controls all internal operations of the solid-state drive, which not only directly affects the performance and stability of the solid-state drive, but also affects its life. Excellent firmware contains advanced algorithms that can reduce unnecessary writes to solid state drives, thereby reducing wear and tear on flash memory chips, maintaining performance and extending the life of solid state drives. Therefore, it is very important to update the latest firmware officially released in time. Not only can it improve performance and stability, but it can also fix previous bugs.

V. Learn to use recovery instructions

The solid state drive's Trim reset command can completely restore performance to the factory state. However, it is not recommended to use it too much, because for a solid state hard disk, every Trim reset is equivalent to completing a complete erase operation, which will affect the disk life. ^[7]

With the rapid development of the Internet, people's storage requirements for data and information are also constantly increasing. Now many storage vendors have launched their own portable solid-state drives, more mobile solid-state drives that support Type-C interfaces, and solid-state drives that support fingerprint recognition. roll out.