Shulou(Shulou.com)11/24 Report--

In the recent Xiaomi 14 series press conference, Lei Jun announced a technology called "Xiaomi Ultra Space storage expansion".

Xiaomi did a lot of bottom reconfiguration when developing the OS, and found that the extra reserved space for the memory chip in the past was very large, and there was at least extra 10GB space waste in the 256GB.

Xiaomi engineers wanted to rewrite the system firmware, and the modified product saved this space, which was adopted after verification with the supplier. In the end, the 16+512GB version of Xiaomi 14 / 14 Pro can have more 16GB space, and the 8+256GB version of Xiaomi 14 Pro can also have more 8GB space.

Some netizens are opposed to this technology, and their views are mainly focused on the following aspects:

1. OP (reserved space) exists all the time. Although it is not visible to ordinary consumers, it is not very difficult for developers to change the size of OP. Xiaomi's "technological upgrade" of changing the size of OP is not a "technological innovation".

2. Reducing the OP space will affect the flash memory lifetime.

3. No matter 256GB multi-8GB or 512GB multi-16GB, there is little improvement.

So what about this technology?

How does Xiaomi change the memory chip? A piece of mobile storage labeled 256GB actually has more real space than 275GB. 93.1% of the space is actually available to users, and the remaining 6.9% is called Over Provision, or OP for short, which is occupied by internal management of the memory.

Engineers began to think that if they could buy some space from the OP area for users without affecting the phone's performance, then users would have more space to store their photos, videos and apps. So Xiaomi began to try.

Xiaomi works closely with memory manufacturers. First, Xiaomi modified its space management strategy to reduce the space occupied by the OP area from 6.9 per cent to about 3 per cent. This process requires an in-depth understanding of how the memory works to ensure that the OP area space is compressed without affecting the performance and lifetime of the memory. After many tests and optimization, Xiaomi found an ideal balance.

To sum up, Xiaomi does get extra capacity by changing the size of the OP. But at the same time, Xiaomi also ensures life and performance through optimization of software and firmware.

The most critical life issue, I believe many digital enthusiasts know that for storage products, reducing the size of the OP is likely to affect the life of the product. Especially for digital products such as mobile phones, the warranty period is generally only one year. As a result, many netizens will worry that Xiaomi's magic modification of the memory chip will lead to the "planned scrapping" of the phone (the phone breaks down just after the warranty period).

In response, Zhang Guoquan, director of Xiaomi's mobile system software department, posted a long post on Weibo to explain the problems. Zhang Guoquan said: "according to the current model of heavy users, under the condition of writing 40GB data every day, the expansion chip of 256GB can still be guaranteed for more than 10 years and 512GB for more than 20 years."

If calculated according to this data, the 256GB expansion chip life is about 142.6 TBW,512GB, and the expansion chip life is about 285.2TBW. We can make a rough comparison of the lifetime of some of the more mainstream solid state drives on the market:

In the 512GB gear, the endurance grade of posture TiPlus7100 512GB version is 300TBW, Western Digital WD_BLACK SN770 500GB version is 300TBW, Pro 512GB version is 500TBW, Samsung 980 PRO 500GB version is 300TBW, and posture Ti600 500GB version (the solid state drive is QLC particles, other control samples are TLC) is 200TBW.

In other words, the life of Xiaomi's 512GB expansion chip is only slightly lower than that of mainstream TLC solid-state drives, but significantly stronger than QLC solid-state drives. And SSDs tend to have a five-year warranty, while many consumers tend to replace their phones within five years. Therefore, according to this life data, ordinary consumers do not have to worry too much about the life of the "expansion chip".

Let's make a simple conclusion about the cost of OP reduction: when other conditions are roughly the same (such as the same firmware or read-write strategy), the larger the OP, the better the performance and durability. However, the disadvantage is that the available capacity will be relatively small.

Taking these solid state drives in Kingston as an example, it is not difficult to find that when the proportion of OP increases, the 4K write performance and durability have been significantly improved.

About improving performance: because each NAND flash module is made up of multiple blocks, and each block contains multiple pages. NAND flash memory can be read and written at the page level, but can only be erased at the block level.

If you need to modify or erase a single page on a written page in a block, the entire block content containing multiple pages must first be read into temporary memory and then erased before the new block content can be written to the same block address.

Only when the page is already blank, the page is written directly to the block in NAND flash memory without going through this tedious read-modify-write cycle. Keeping a large number of blocks blank and reserved by reserving space helps to maintain performance consistency, especially when random writes exhibit the highest write magnification (WAF).

On improving durability: first of all, because each NAND flash chip has a limited service life, depending on its program and erase durability (P / E), this characteristic is determined by the manufacturing process of the NAND flash memory manufacturer, because every program or erase operation performed on the NAND flash chip consumes the chip's ability to reliably store charges, thus posing a threat to data integrity.

When a piece of flash memory runs out of life, you need to find a piece from the OP to replace it. The larger the OP, the more blocks you can replace and the better the durability. When the OP is exhausted, the whole hard drive is not far from being scrapped. (at this point, some solid state drives will disable write operations.)

Cheating "poor method" about the technology of "Xiaomi Ultra Space storage expansion" announced by Xiaomi this time, it can actually be evaluated as a tricky "poor method".

For any mobile phone with 256GB capacity, what if the capacity is not enough? The most direct way is to buy a 512GB version of the phone, which doubles the capacity directly. But the drawback is that it costs more.

The proportion of OP is actually similar. Many enterprise SSDs have a high proportion of OP, but the price is that more flash chips are needed to deliver the same capacity to customers. And you still have to pay more to use more flash chips with larger capacity.

Therefore, Xiaomi's expansion technology is actually on the basis of no extra money to ensure that the life of the hard disk is sufficient, the additional "development" of part of the capacity.

Related readings:

"the additional 8GB storage capacity of Xiaomi 14 mobile phone is expanded: the old model does not support it, and it will be opened to competitors later."

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