在看似非常突然的举动中，SSD技术已成为主流。即使是中档计算机，这些快速的固态驱动器也是常见的功能。甚至下一代Playstation也将配备 SSD(feature an SSD)而不是更传统的硬盘驱动器。
总的来说，这是一件好事。SSD(SSDs)代表了与传统硬盘驱动器相比性能的重大飞跃。但是，它们也带来了一些特殊的使用和维护注意事项。大多数阅读本文的用户可能已经在他们的系统中安装了SSD，或者几乎肯定会在他们的下一个系统中安装 SSD。
因此，是时候解开SSD技术独有的最重要但被误解的问题之一了。我们谈论的是SSD磨损。驱动器的神秘杀手，让许多早期采用该技术的人彻夜难眠。
在我们解决SSD的实际磨损问题之前，我们需要简要谈谈SSD(SSDs)与我们都知道和喜爱的硬盘驱动器有何不同。
SSD与传统硬盘(Traditional Hard)驱动(SSDs)器有何不同(Differ)
传统的机械硬盘驱动器由涂有特殊磁性材料的盘片组成。盘片以每分钟数千转的速度旋转，而读/写头在比人类头发还细的空气袋上滑过它们的表面。
第一个硬盘驱动器如此之大，以至于它们需要一架飞机来交付(needed an airplane for delivery)——同时只保存几兆字节的数据。如今，一个 4TB 的便携式硬盘可以轻松放入您的口袋。与最初的情况相比，这些驱动器便宜、容量大且相当可靠。
然而，机械硬盘驱动器技术没有希望跟上固态计算机组件（如CPU(CPUs)、RAM和闪存）的进步。盘片只能旋转得如此之快，读/写头只能移动，因为物理定律允许具有这么大质量的物体做。
固态驱动器没有移动部件。都是半导体电路。电子可以比任何机械组件更快地(much)穿过硅芯片。这(Which)就是为什么即使是最便宜的 SSD 也会在性能上完全抹杀机械驱动器。
由于它们没有机械部件，因此它们的物理脆弱性也大大降低，并且更不容易发生故障。另一方面，简单地使用SSD会缩短其使用寿命，如果您以错误的方式使用它们，这种缩短可能会非常显着。发生什么了？
为什么 SSD 会磨损？
首先(First)，从SSD读取数据对其使用寿命没有任何明显影响。相反，写入闪存单元的行为会降低它的性能。SSD中的每个存储单元都有一个氧化物成分。两层与氧气混合的一种或另一种化学物质。电子被困在这些氧化物层之间。
给定电池的状态取决于充电水平。换句话说，有多少电子被困在氧化层之间。每次改变这种状态时，氧化层都会磨损，最终失去容纳电子的能力。这会使状态无法正确读取。对一个单元格写(Write)太多次，它最终会变坏。
SSD 技术类型和耐用性
虽然所有SSD(SSDs)都会遭受写入磨损，但它们的容忍度并不相同。有不同的存储单元设计，它们改变了单个单元中可以存储多少信息。
最稳健的设计称为SLC或单级单元(single level cell)存储器。这仅在单元格中存储一位数据，使其成为二进制。因此，即使在发生大量磨损之后，也很容易区分代表一种状态或另一种状态的充电水平。
MLC 和TLC设计，多级和三级，每个单元分别存储两位和三位。它们的单元格具有多个级别，因此必须读取许多不同的状态。由于不同电池状态之间的裕度较窄，即使是少量磨损也会导致电子容量问题，从而无法回忆起正确的状态。
所以我们应该只使用SLC，对吗？问题是SLC在每 GB 的基础上非常昂贵。它快速而强大，但不是很密集。如今，计算机中的大多数高级SSD驱动器都使用MLC，并且由于容量更大且价格合理， TLC变得越来越流行。(TLC)
那么在实践中，这些便宜的产品缺乏续航能力，你有多少担心呢？
SSD 耐力实践
今天这个问题的答案是“一点也不”。在计算机SSD(SSDs)的早期，您可以通过写入请求在几个小时内将其销毁。今天，您可以期望多级驱动器具有比典型用户所需要的更多的写入耐久性。
这有几个原因，但归结为驱动器本身更加智能，并且现代操作系统知道如何正确使用SSD驱动器。
例如，SSD(SSDs)现在使用一种称为磨损均衡(wear-leveling)的技术。这透明地将单元写入分布在整个磁盘周围，以便均匀地发生磨损。否则，一些细胞会比其他细胞死得更快。
那么你可以期待多少写入耐力？最新一代的驱动器，例如三星 950 Pro 512GB 驱动器(Samsung 950 Pro 512GB drive)具有 400TB 的写入耐久性。但是，许多人仍在使用流行的旧驱动器，例如850 EVO。该驱动器的额定容量“仅”为 150TB。
酷刑测试(Torture tests)表明，这个评级是非常保守的。在现实生活中使用该型号的驱动器在放弃幽灵之前进行了高达 9100TB 的写入。所以 150TB 数字只是制造商不再履行保修的点。
尽管如此，消费级驱动器不应该用于任何经常发生大量磁盘写入的工作。它们不适合服务器使用或用作重型媒体暂存驱动器。然而，对于普通的日常消费者使用而言，写入耐力是您永远不必花时间思考的事情。
购买一个好的驱动器品牌(Buy a good brand of drive)，无论哪种方式，都要定期备份您的关键任务数据。
Everything You Need To Know About SSD Wear & Tear
In what ѕeems like a very sudden move, SSD technology has gone mainstream. These fast, solid-state drives are a common feature on evеn mid-range computers. Even the nеxt generation of Рlaystation will feature an SSD instead of a more traditional hard drive.
In general this is a good thing. SSDs represent a major leap in performance over traditional hard drives. However, they also bring some special usage and maintenance considerations with them. Most users reading this probably have an SSD in their system already or will almost certainly get one in their next system.
So the time is right to unpack one of the most important, yet misunderstood, issues unique to SSD technology. We’re talking about SSD wear and tear. The mythical killer of drives that has kept many an early adopter of this technology awake at night.
Before we can tackle what SSD wear and tear actually is though, we need to briefly talk about how SSDs are different from the hard drives we all know and love.
How SSDs & Traditional Hard Drives Differ
The traditional mechanical hard drive consists of platters coated in a special magnetic material. The platter spins at thousands of revolutions per minute, while read/write heads skate across their surfaces on a pocket of air thinner than a human hair.
The first hard drives were so big, they needed an airplane for delivery – while only holding a few single megabytes of data. These days a 4TB portable hard drive easily fits in your pocket. These drives are cheap, capacious and pretty reliable compared to how things were at the outset.
Yet, mechanical hard drive technology has no hope of keeping up with the advancement of solid state computer components such as CPUs, RAM and flash memory. Platters can only spin so fast, read/write heads can only move as the laws of physics allow objects with that much mass to do.
Solid state drives have no moving parts. It’s all semiconductor circuitry. Electrons can move through silicon chips much, much faster than any mechanical components ever could. Which is why even the cheapest SSD will completely obliterate a mechanical drive in performance.
Since they have no mechanical parts, they are also much less physically fragile and far less prone to failure. On the other hand, simply using an SSD will shorten its lifespan and if you use them in the wrong way, that shortening can be quite dramatic. So what’s going on?
Why Do SSDs Wear Out?
First of all, reading data from an SSD doesn’t have any appreciable effect on its lifespan. Instead, it’s the act of writing to the flash memory cell that degrades it. Each memory cell within an SSD has an oxide component. Two layers of one or another chemical mixed with oxygen. Electrons are trapped between those oxide layers.
What a given cell’s state is, depends on the charge level. In other words, how many electrons are trapped between the oxide layers. Every time that state is changed, the oxide layers wear down, eventually losing their ability to contain electrons. This can make the state impossible to read correctly. Write to a cell too many times, and it eventually goes bad.
SSD Technology Types and Endurance
While all SSDs suffer from write wear, they don’t all have the same amount of tolerance for it. There are different memory cell designs, which change how much information can be stored in a single cell.
The most robust design is known as SLC or single level cell memory. This stores only a single bit of data in a cell, making it binary. It is therefore quite easy to distinguish between a charge level that represents one state or another, even after quite a lot of wear has happened.
MLC and TLC designs, multi- and triple- level, store two and three bits per cell respectively. Their cells have multiple levels and therefore many different states that have to be read. Since the margins between different cell states are narrower, even a small amount of wear can cause electron capacity issues that make it impossible to recall the correct state.
So we should only use SLC, right? The problem is that SLC is incredibly expensive on a per-gigabyte basis. It’s fast and robust, but not very dense. Most of the premium SSD drives in computers these days are using MLC, and TLC is becoming more popular thanks to bigger capacities at a good price.
So how much do you have to worry about the lack of endurance of these cheaper products in practice?
SSD Endurance In Practice
The answer to that question today is “not very much at all”. In the early days of computer SSDs you could destroy one in just a few hours by hammering it with write requests. Today you can expect multi-level drives to have way more write endurance than the typical user will ever need.
There are a few reasons for this, but it comes down to the drives themselves being much smarter and modern operating systems knowing how to use SSD drives properly.
For example, SSDs now use a technique known as wear-leveling. This transparently spreads cell writes around the entirety of the disk so that wear happens evenly. Otherwise some cells would die much more quickly than others.
So how much write endurance can you expect? The latest generation of drives, such as the Samsung 950 Pro 512GB drive has a write endurance of 400TB. However, many people are still using popular older drives such as the 850 EVO. That drive is rated for ‘only” 150TB.
Torture tests show that this rating is very conservative. In real life use that model of drive took a whopping 9100TB of writes before giving up the ghost. So the 150TB number is just the point at which the manufacturer won’t honor the warranty any more.
Still, consumer grade drives should not be used for any job where lots of disk writing happens on a constant basis. They’re no good for server use or as heavy media scratch drives. For normal every day consumer use however, write endurance is something you’ll never have to spend any time thinking about.
Buy a good brand of drive and, either way, make regular backups of your mission-critical data.
