SSD or HDD - what is the difference?
Modern computers use two types of drives:
- SSD (Solid-State Drive), better known as solid state drives.
- HDD (Hard Disk Drive), also called hard disks.
How SSDs work
SSD is faster and more modern, but so far "hard drives" also remain relevant for a number of reasons. In this article we will consider the principles of both types of drives, their advantages and disadvantages. We will also tell you what to look for when buying.
SSDs are non-mechanical storage devices that are many times faster than traditional HDDs. They use high-speed flash memory to store information, and the controller provides access to this data. The data is contained in NAND memory, which consists of links of floating-gate transistors. This design allows you to maintain a charged state when disconnecting the drive from the network. As a result, all data is stored on the computer when it is turned off.
How HDDs work
Hard disks also belong to the class of storage devices, but have a radically different principle of operation, reminiscent of old tape recorders. There is a working surface of a disk and a head for reading combined with the basic design by a rotating shaft. Magnetized heads move on plates, writing and reading information. This is a strong simplification, but enough to form a general picture of the principles of HDD. As we can see, the differences between HDD and SSD are significant. The principle of operation of the former is based on mechanical phenomena, and the latter belong to the category of non-mechanical memory. They simply have no moving parts.
Here we come to the first important point - the types of memory. While browsing online store directories for the right SSD, you could see devices with four types of memory:
- SLC. These are drives with one-level cells, ie in each block is written or 0, or 1. If we speak in the language of memes "the fastest hand in the Wild West". SLC cells transmit information faster than their counterparts, but have a much smaller capacity. In addition, they are durable and reliable - each cell is designed for 100 thousand rewrite cycles. Hence their high cost, especially if you consider models with a modern controller. They are almost non-existent in the consumer segment, so you can immediately look in the direction of the other three.
- MLC. Memory cells are four-level (two charges per cell). Second place for speed and reliability. SSDs with MLC can withstand about 10,000 rewrite cycles, which is also a surplus for ordinary consumers. This memory is mainly equipped with high-speed models such as the Samsung 860 Pro series, designed for the corporate segment and IT companies. However, if read / write speed and reliability are a priority for you, you can safely look at drives with MLC. They are expensive, but trouble-free and durable, withstand about 2 million hours of operation.
- TLC. Logical development of MLC with 8-level cells (3 bits). This was achieved through fine-grained charge control of cells with increased reading sensitivity. In 2020, this is the most common type of memory for both internal and external SSDs. It is a compromise between speed and reliability at a balanced price. Must have for everyday use and games. But remember: in terms of speed and durability, TLC memory is much inferior to MLC, withstanding only 3-5 thousand rewrite cycles.
- QLC. The most budget-friendly memory, capable of storing 4 bits of data per cell. In terms of speed and durability, this is the worst option, especially when it comes to writing / reading many small files. But a gigabyte of QLC memory is extremely cheap, and it will be enough for everyday tasks. If you search, for $ 100 you can really choose a model with a capacity of about 800-1000 GB. With MLC or TLC drives it will not work - for the same money you can find a maximum of 400-500 GB.
To summarize, everything is simple. For expensive PCs and laptops, choose MLC. Expensive, fast, long lasting. In professional activities and games will not disappoint. TLC is the same, but a little cheaper and worse in terms of durability. A good option for a mid-range PC. If you do not record large amounts of data regularly, you will not notice much difference. QLC is better not to take at all, frankly. Except for a small upgrade of an old laptop or PC - in this case, it just does not make sense to buy something expensive and better.