How important is the hard disk cache? After you read it, you will understand

Last week, "News Tea Fan" Xiao Bian pushed about the new cache-free SSD hosting program launched by Chonglian Electronics, and some of the small partners left a message asking what happened to the non-cached SSD. After all, the SSD was only a long time ago. When there is a rise, there will be no cached master products. The importance of this cache is not important to many people want to know, Xiaobian said today.

The role of hard disk cache

"Cache" exists to balance the speed difference between high-speed devices and low-speed devices. For the simplest example, the data in memory should be stored in the mechanical hard disk. Since the mechanical hard disk is much slower than the memory, theoretically it takes a long time to complete the task, and the result is that the write is super slow.

To solve this speed difference (memory speed and hard disk speed), you need to do a "buffer" to temporarily store data, which is the role of the hard disk cache. However, it should be noted that in fact, the hard disk cache is not all used to cache data, there are other uses, so not necessarily the greater the cache, the better the performance.

And there is a problem with the caching algorithm. If the algorithm is not good, the hit rate will not be high, so that the large-capacity cache is useless, and even the speed problem will occur. In addition, this must be combined with the disk's own platter capacity and speed. For example, a hard drive with a sustained read/write speed of about 150MB/s or so and a single-disc capacity of no more than 1TB capacity is sufficient for caching 64MB. 128MB is obviously wasted; only those with a single-disc capacity exceeding 1TB and continuous read/write performance at around 200MB/s The mechanical hard drive, 128MB of cache makes sense.

SSD cache

Compared to mechanical hard drives just mentioned, SSDs are a lot faster, but they are still much slower compared to memory. The SSD cache is generally used as a cache with one or two DRAM particles (white particles are memory particles). Whether the SSD was cached earlier is a very important indicator. The low-end entry-level products even have no cache design, and their service life and performance must be a lot worse. In the current high-speed products due to the large amount of data exchange, the cache is already a standard for solid-state hard drives, which is used to improve product read-write performance.

Why is the new hard disk not cached yet?

Since the function of caching is almost decisive for the hard disk, why should the new master control also emphasize non-cache design? This is because the SSD of the SSD is "having cache" in another way. The new technology of the gang is called "HMB memory buffering technology." In simple terms, it is to remove what should have appeared on the hard disk. Cache, to find memory to borrow storage space, to achieve data buffer!

The benefit of this is that the cost will be reduced, and the SSD will reduce the cost due to one fewer cache particles. However, with the new technology, the cached SSD speed can still be achieved.

However, this is also a price: the memory capacity is bound to be partially occupied. From the perspective of Xiao Bian, I am afraid that computers with more than 16 GB of memory can use this technology. Otherwise, the system and software applications will not occupy enough memory, plus the solid state. Hard disk to borrow memory as a cache, is undoubtedly a matter of worse.