There is a significant difference between modern SSDs and HDDs. They are fundamentally different from each other in the principle of operation and have both their advantages and disadvantages in use.
History
From the earliest days of the first computers, there was one very important problem - how to store the necessary information. The calculation results and input data were stored on various media. The first computers used punched cards: ordinary cardboard boxes with holes representing 0 or 1. Over time, other types of storage devices such as audio cassettes, magnetic floppy disks, hard disks, and solid state drives appeared. The first hard drive was released by IBM in 1956. The device was intended for the first "SUPER" computer with a 305 RAMAC hard drive. The drum rotation frequency was 1200 rpm, and this system weighed about a ton and consisted of 50 discs with a diameter of 610 mm. Each disk corresponded to 100 kilobytes, which is considered too small by modern standards.
Solid-state drives appeared a little later, in 1978 from the American company StorageTek, it was built on the architecture of volatile memory, which, in fact, was RAM, rather than a flash drive. The first flash drive was released in 1995 by the Israeli company M-Systems. Until about the 2000s, flash memory was significantly inferior in performance to hard drives, but progress was relentlessly moving forward. Since 2012, it has already been possible to find the same super-fast SSD drives on the market that we are used to using.
The main differences
HDD, also known as hard drive, is a small palm-sized device made of metal, plastic and a control board with connectors for connection. Its principle of operation resembles a tape recorder. Inside you can see rotating disks (that's why it is called that) and read heads (each disk has its own head) with a speed of 5400-10000 rpm, as well as a controller consisting of buffer memory and connection interfaces. Only 2 form factors are popular now - these are 2, 5 and 3.5 inches, which can be found in almost any computer hardware store. The controller board of modern HDDs has 2 connectors: power supply and data transfer (SATA interface). Large 3.5-inch hard drives are cheaper, have more information, consume more power, can be very noisy and take up more space. Small 2.5-inch drives are used in portable electronics like laptops and media players. They are much smaller in size, tend to be more expensive, have worse performance, hold less information, but consume less energy and create a minimum of acoustic and vibration discomfort during use.
The SSD is made a little simpler, it has no moving parts, it's just a board with memory elements and a controller soldered on it. There are two types of memory - RAM and NAND. RAM memory is volatile, information is stored in it as long as the necessary power is supplied to it, as soon as you turn off the electricity, all information will disappear. NAND memory does not depend on electricity, when disconnected from the power, information remains stored for an infinite amount of time, and it can be accessed by applying power. NAND memory is used in solid state drives. Typically, ssd drives come in a 2.5-inch form factor, making them ideal substitutes for devices that already have a drive of this size. But this connection method has a big drawback in the form of limited baud rate of connectors. To fix this problem, a special M.2 interface was developed. It can be used directly through the motherboard or using a PCI Express adapter. M.2 drives are even smaller than 2, 5, they work even faster, but the cost of such devices is about 10-15 times more expensive than HDD.
Pros and cons of each type of device
SSD Solid State Drive
Pros:
- There are no moving parts, high mechanical resistance to external influences and no noise;
- The read and write speed is much higher than that of a hard disk, about 4-10 times;
- Stable read and write speed regardless of the size and position of files in the file system;
- Very low power consumption.
Minuses:
- The main disadvantage of flash memory is the limited number of rewriting cycles. For a good storage device, this number usually reaches 3,000 - 10,000 times. The cheaper ones may not even reach the 1000 mark, so at any time you can irrevocably lose all the information, without wanting to;
- Very high cost of 1GB relative to hard drives. At the moment, the cost of a 120GB solid state drive is about the same as the cost of a 1TB hard drive;
- The complexity, and sometimes the impossibility of recovering information from a Flash drive due to its complex structure.
HDD Hard disk
Pros:
- Cost for 1GB of information;
- Large volume in the size of 1 device. Now you can find hard drives even 16TB in the 3, 5 format;
- Relative reliability of information storage. In fact, a hard disk has no limit on the amount of data rewriting, it can only become obsolete in the mechanical part;
- If the device stopped working, then there is a high probability not only to restore all data, but also to fix the device for further work.
Minuses:
- The write speed is lower than that of solid-state drives, not even saved by the speed of 10,000 rpm and the expanded cache size up to 64MB;
- Very poor read / write stability. For example, 1 file weighing 1 GB can be copied faster than 1000 files of 1 KB (this is about 1000 times less than 1 GB), while the SSD will cope with the second task in a couple of seconds;
- Noise and vibration from work, especially on server versions, where the main thing is productivity, not user comfort;
- High energy consumption due to moving parts: read heads and rotating motor.
Recommendations to users
Thus, each of the storage media we have considered can be used for different purposes: to store a large amount of data, it is better to use an HDD, and for good performance, an SSD. When assembling or modifying a personal computer or laptop, the golden mean is the combined use of a flash drive and a hard drive. The operating system and all the necessary programs are installed on the solid-state drive, since they, as a rule, consist of many very small files in size, and are scattered throughout the space, and all the necessary information, such as photographs, videos and documents, is already stored on the hard drive. The system can always be restored, and your personal files may be lost forever. For computers that do not have hard drives like Ultrabooks, Tablets or MacBooks, it is highly recommended that you back up your data to hard drives at least once a month, any portable HDD or home cloud storage like Apple's Time Capsule or Western's My Cloud will do. Digital, it's not for nothing that system administrators, when making backups, say - “one copy of data is zero copies of data”. Even in spite of the archaic nature of hard drives, at this stage in the development of technology they remain the most reliable and widespread custodians of information.
