长期存储正在发生变化。我们习惯于使用硬盘驱动器(hard disk drives)(HDD)，现在我们中的许多人都拥有固态驱动器(solid-state drives)( SSD )。但是什么是电子多媒体卡 (eMMC)，为什么我们在笔记本电脑而不是SSD(SSDs)和HDD(HDDs)中看到它？
我们已经知道SSD(SSDs)通常优于HDD(HDDs)，所以让我们重点比较 eMMC 与SSD(SSDs)以及两者的优缺点。
什么是固态硬盘？(What Is SSD?)
如果您不知道，固态驱动器是一种全电子长期数据存储组件。固态最简单的解释是没有运动部件。从技术上讲，固态是指使用半导体的电子产品。
没有移动部件意味着没有摩擦，因此磨损更少。这也意味着数据移动得更快，因为它不必等待盘片旋转和读写臂移动到您需要的数据。
SSD驱动器具有三种适用于笔记本电脑的外形尺寸；2.5寸机箱像硬盘(HDD)，mSATA像卡，M2像内存(RAM)。
什么是 eMMC？(What Is eMMC?)
乍一看，eMMC 似乎是一种固态硬盘。它没有任何移动部件，而且速度非常快。
关于 eMMC 本质的一个重要线索是名称中的多媒体卡部分。如果这让您想到 SD 或 microSD 卡，那么您的想法是正确的。这基本上就是eMMC。
eMMC 和 SD 卡是按照相同的基本标准构建的，并且按照相同的原理运行。如果您有智能手机或平板电脑，那么您可能已经有了一个带有 eMMC 的设备。
那么有什么区别呢？(What’s The Difference Then?)
我们已经谈到了它们具有不同的外形尺寸和物理尺寸的事实。我们还看到SSD(SSDs)可以轻松拆卸和更换，但 eMMC 焊接在主板上。如果您需要更换它，您最好购买另一台笔记本电脑。
目前，可用的最大容量 eMMC 仅为 128GB。eMMC 是智能手机中使用的存储(storage used in smartphones)类型，因此它们的上限为 128GB。如果您曾经看到列出的 eMMC 容量为1(B) Tb，请了解 Tb 代表Tera b its，而 TB 代表Tera (T)B(T) ytes 。一个太比特大约是 125 GB。1 TB 为 1000 GB。了解存储容量大小(Understanding storage capacity sizing)很重要。
可用的最大 SSD 为 60 TB，而且似乎每个月都在增长。eMMC 的尺寸也可能会增长，但要赶上SSD(SSDs)需要很长时间。
eMMC 与 SSD：性能差异(eMMC vs SSD: Performance Differences)
如果我们打开一个SSD，你会看到几个看起来像 SD 卡的芯片。这些芯片只能执行这么多的read/write operations。使用多个芯片可以平衡读/写操作，从而使每个芯片的使用寿命更长，这意味着整个 SSD 驱动器的使用寿命会更长(the whole SSD drive will last longer)。
如果你打开一个 eMMC，你会看到它里面只有一个芯片。所以所有读/写都只命中一个芯片。当然，这意味着它的寿命将比相同容量的SSD更短。(SSD)
SSD和 eMMC 芯片的关键组件是NAND门。关于NAND(NAND)门的重要知识是它可以被认为是一个实际的门。因为 eMMC 是单芯片，它只有这么多门，而SSD有几个芯片，所以它有更多的门。
可以将 eMMC NAND门想象成一个带有收费站的单车道公路，而SSD就像一个有多个收费站的 16 车道高速公路。给定相同的流量，SSD每次都会获胜。
eMMC 与 SSD：成本差异(eMMC vs SSD: Cost Differences)
很快就会发现 eMMC 笔记本电脑比SSD笔记本电脑便宜很多。差价通常是几百美元。部分原因是SSD有更多的部件并且制造成本更高。
我们还会发现配备SSD的笔记本电脑还将配备其他更高端的组件，例如更好的视频和更多的RAM。需要SSD驱动器的人通常会将笔记本电脑用于Facebook和购物以外的用途。他们需要一台比大多数拥有 eMMC 的笔记本电脑更坚固的笔记本电脑。这占成本差异的很大一部分。
什么更好？SSD 还是 eMMC？(What’s Better? An SSD Or An eMMC?)
这取决于您的需求。
如果您需要一台负担得起的笔记本电脑(need an affordable laptop)，将您的数据存储在云(store your data in the cloud)中，并且存储在笔记本电脑上的数据并不重要，那么 eMMC 笔记本电脑可能是最好的。基于 eMMC 的笔记本电脑非常适合休闲使用。对于只做一些报告写作和网上冲浪的普通学生来说，这很有好处。他们制作了一台很好的辅助笔记本电脑或平板电脑的替代品。
如果您需要一台具有大容量、可靠的本地存储和快速数据访问的笔记本电脑，那么SSD笔记本电脑可能是最好的选择。当然，成本会更高。对于具有较重工作负载（如编程、游戏、设计工作或多任务处理）的主笔记本电脑来说，这是一条路线。
eMMC vs SSD: What’s The Difference?
Long term storage is chаnging. We’re usеd to using hard disk drives (HDD) and many of us now have solid-state drives (SSD). But what is the electronic multi-media card (eMMC) and why are we seeing it in laptops instead of SSDs and HDDs?
We already know that SSDs are generally superior to HDDs, so let’s focus on comparing eMMC vs SSDs and the strengths and weaknesses of both.
What Is SSD?
In case you’re not aware, a solid-state drive is an all-electronic long-term data storage component. The simplest explanation of solid-state is that there are no moving parts. More technically speaking, solid-state means electronics that use semiconductors.
No moving parts mean no friction so less wear and tear. It also means that the data moves quicker since it doesn’t have to wait around for platters to spin and the read-write arm to move to the data you need.
SSD drives come in three form factors for laptops; 2.5-inch chassis like an HDD, mSATA which looks like a card, and M2 which looks like RAM.
What Is eMMC?
At first look, the eMMC seems to be a type of solid-state drive. It doesn’t have any moving parts and it’s pretty fast.
A big clue about the nature of eMMC is the multi-media card part of the name. If that makes you think of SD or microSD cards, you’re thinking in the right direction. That’s basically what eMMC is.
The eMMC and SD cards are built to the same basic standard and operate on the same principles. If you’ve got a smartphone or tablet, you’ve probably got a device with eMMC in it.
What’s The Difference Then?
We already touched on the fact that they have different form factors and physical sizes. We’ve also seen that SSDs can be easily removed and replaced, but an eMMC is soldered to the motherboard. If you needed to replace it, you’re probably better off buying another laptop.
Right now, the largest capacity eMMC available is only 128GB. eMMC is the kind of storage used in smartphones, so that’s why they cap out at 128GB. If you ever see an eMMC listed as having 1 Tb capacity, understand that Tb stands for Terabits, while TB stands for TeraBytes. A Terabit is about 125 GB. A Terabyte is 1000 GB. Understanding storage capacity sizing is important.
The largest SSD available is 60 TB, and that seems to grow every month. eMMCs will likely grow in size too, but it’ll take a long time to catch up to SSDs.
eMMC vs SSD: Performance Differences
If we were to open an SSD, you’d see several chips that look like SD cards. These chips can only perform so many read/write operations. Having several chips to work with balances the read/write operations so that each chip lasts longer, meaning the whole SSD drive will last longer.
If you opened an eMMC you’d see it only has one chip in it. So all read/write hits just one chip. Of course, that means that it will have a shorter lifespan than an SSD of the same capacity.
The key component in both SSD and eMMC chips is the NAND gate. What’s important to know about the NAND gate is that it can be thought of as an actual gate. Because an eMMC is a single chip it only has so many gates, while the SSD has several chips so it has far more gates.
Think of the eMMC NAND gate as being like a single lane road with a toll booth, while the SSD is like a 16-lane highway with several toll booths. Given the same amount of traffic, the SSD is going to win every time.
eMMC vs SSD: Cost Differences
It doesn’t take long to see that an eMMC laptop is a lot less expensive than an SSD laptop. The difference is usually a few hundred dollars. Part of that is because an SSD has more parts and is more expensive to make.
We’ll also find that a laptop with SSD is also going to have other higher-end components, like better video and more RAM. A person who needs an SSD drive is typically going to use that laptop for more than Facebook and shopping. They need a more substantial laptop than most that have eMMC. That accounts for a big part of the cost difference.
What’s Better? An SSD Or An eMMC?
It depends on your needs.
If you need an affordable laptop, store your data in the cloud, and your data stored on the laptop isn’t critical, then an eMMC laptop may be best. The eMMC based laptop is fine for more casual use. It’s good for the average student who is only doing some report writing and web surfing. They make a good secondary laptop or a substitute for a tablet.
If you need a laptop with large, reliable, local storage and fast data access, then an SSD laptop may be best. Of course, it will cost more. This is the route to go for a primary laptop with heavier workloads like programming, gaming, design work, or multi-tasking.
