This is a common assumption that comes up time and time again. I have had many Production Managers assure me that 'I got Thunderbolt Drives so they'll be the fastest and we'll be covered'. This is almost never true and I would like to explain why. Dive deep into the wonderful world of hard drive speeds.
WHAT IMPACTS THE SPEED?
Many parts and components make up a hard drive that you buy off the shelf. Each and every one of these parts plays a role in the end performance that you will experience as a user. I summarize them as the 4 Pillars of Hard Drive Performance: Drive, Enclosure, Connection Interface, Cable / Computer Interface
The physical drive that lives inside your hard drive is the key player when it comes to speed. Most commonly you would know this as Hard Disk Drive (HDD) or Solid State Drive (SSD).
HDDs are made up from multiple magnetic platters that physically spin inside the drive. Your data is stored on these magnetic platters and a read/write arm moves across them to record your data and to recall your data when it is required. These are the most affordable drives, yet due to their mechanical nature they have poorer performance when it comes to speed.
SSDs are made from flash storage chips that are housed on a Printed Circuit Board (PCB). There are no moving parts, all of the legwork is done by the copper connections and the circuits. These drives are more expensive but also offer the best performance.
In any consumer hard drive product you will find a HDD or SSD inside of a wonderful housing, this housing is known as the enclosure. The enclosure is what you typically think of when you imagine a hard drive. Some enclosures are made of plastic, others are made of aluminum. This material choice plays a small role in heat dissipation but is largely about durability, aesthetics and price.
What we are really concerned about is speed. What part of the enclosure impacts speed? It's the PCB or circuit board. The PCB inside of an enclosure essentially acts as an intermediary between the drive and the computer. Think of it as the knife that bridges the gap between the force of your cutting hand and a piece of food. Or the tennis racquet that transfers the strength of your arm to the force of a moving tennis ball. In the same way a sharper knife or a lighter racquet gives you better results, an effective enclosure will provide you with absolute speed.
The two main players on the circuit board are the SATA Connection and the Connection Interface. We will cover Connection Interface below as it's incredibly important and worthy of it's own pillar, but the SATA Connection should not be overlooked. Below is an image if a bare bones HDD, the connector on the bottom is what a SATA Connection looks like:
While all of these numbers may come across as confusing, the one thing that you need to know is that a newer revision of SATA means faster speeds. This isn't a common cause of a slow hard drive but it does crop up from time to time and is worthy of your time and consideration.
You will typically know of connection interfaces as USB3, USB3.1, Thunderbolt 2, Thunderbolt 3, Firewire 800, eSATA, etc. I would define these as external connection interfaces, while the SATA Revisions that we just discussed are considered internal connection interfaces.
Each one of these connection interfaces runs at a different speed, some faster than others. You'll see terms being thrown around like '40Gbps' or 'SuperSpeed+', these can be confusing and quite often misleading. We all understand the concept of a Megabyte and most people have a good gauge of how a Megabyte makes up a Gigabyte and a Gigabyte makes up a Terabyte, it's metric and works on the concept of 1000 (1000 Megabytes is a Gigabyte and 1000 Gigabytes are a Terabyte). I believe it's easier to understand when we use terms that we are used to. So let's break it down in Megabytes Per Second (MB/s).
As you can see, there is a wide array of speed difference between different connections which will have an impact on the performance of your hard drive. It's very clear that USB3.0 is slower than Thunderbolt 2, but this difference in speed won't always mean your hard drive will perform slower which we explore below in 'The Weak Link of the Chain'.
CABLE / COMPUTER INTERFACE
So you have a USB3.0 Port on your hard drive, great, but what if you are using a USB2.0 Cable? Or if your computer is an old 17" MacBook Pro that has USB2.0 Ports on the side? Will that impact your speed, yes.
In conjunction with all of the above elements we need to consider the role of the cable and the computer's connection interfaces. This is the last major bridge that your data needs to cross. Today we live in a world with Cable Adapters, USB Hubs and what some would call a wild west of cables coming out of China.
Knowing your computer is simple. The connection interfaces will be in line with the ones that we described above and their speeds the same. You can easily look up your computer specs or a product listing and this information will be accessible.
Cables are a bit trickier. Many have different connectors on each end and the gauge of cable that is between these two connectors can be of varying quality. The cable quality and cable connectors will impact the speed. It's very easy to fall down the rabbit hole when it comes to cables and adapters, this will be explored in a different blog post. For now, you just need to be aware that they play a role in your hard drives performance.
THE WEAK LINK IN THE CHAIN
This is by far the most important concept to understand when it comes to hard drive speed. You know that old saying 'a chain is only as strong as it's weakest link'? The same principle is in effect here. Your hard drive is only as fast as the slowest component in use. In every single hard drive, one of the four pillars (drive, enclosure, connection interface, cable / computer interface) will be the weakest link in the chain and cause a limitation in overall speed. The best way to explore this is by example:
Example 01: (Slow Cable)
Here we see the USB2.0 Cable becoming the weak link in the chain. Despite all of the other upstream components being faster we default to the speed of USB2.0 due to that one cable at the end of our connection.
Example 02: (Slow HDD)
This is a very common limitation, the HDD will be the weak link in the chain. Everything else is offering great speeds but the HDD is stuck at 115MB/s, it's the slowest component and thus will become the max speed we can attain.
Example 03: (Slow Connection and Cable)
When using an SSD, your drive speed surpasses the speed of the common USB3.0 Interface. In this instance you will only be able to use your SSD at 420MB/s despite it being capable of running at 520MB/s. This is because the USB3.0 Port, Cable and Connection is the weak link in the chain.
Example 04: (Slow SSD)
When using high end connections like USB3.1 it is very unlikely that it will be the weak link in the chain. Here you can see the SSD, despite being really fast, has become the slowest component in use and thus the bottleneck in drive speed.
As depicted by the above examples, you can clearly see how the weak link in the chain will hold back all of the other components.
The most common weak link that we see is the drive component. Your standard 5600rpm HDD will run around 115MB/s. All common connection interfaces easily exceed that speed, USB3.0 is faster (420MB/s), Thunderbolt 1 is faster (1000MB/s), USB3.1 is faster (1000MB/s) and Thunderbolt 3 is a lot faster (5000MB/s).
When dealing with SSDs the story is a little different. Most SATA SSDs will run around 520MB/s. When this SSD is connected via USB3.0 you will be capped out by the limitations of USB3.0 (420MB/s), but if you use the same drive via USB3.1 (1000MB/s) you will be once again limited by the drive speed, even though its a fast, solid state drive.
When considering hard drive speed you should first consider your drive (HDD/SSD), then your connection interface (USB, Thunderbolt) followed by your cables, adapters and computer connection interface. The SATA Status of an enclosure is the last thing that I check as it's only a factor in rare circumstances.
WILL THUNDERBOLT MAKE MY DRIVE FASTER?
With all of that said, we land back at our original question. Will Thunderbolt Make My Drive Faster? If you read and understood this article, I'm sure you'd be able to answer that yourself. But allow me to elaborate on my original answer for the sake of being thorough: 'Sometimes, but in most circumstances it won't make a difference.'
Thunderbolt is a connection interface. Indeed there are times where having a Thunderbolt Hard Drive over a USB3.0 Hard Drive will make your drive faster, but this will only occur where all other pillars of hard drive performance exceed the speed of the USB3.0 connection interface. So you need to ask yourself, when will a drive (HDD/SSD) exceed Thunderbolt 1 (1000MB/s), Thunderbolt 2 (2000MB/s) or Thunderbolt 3 (4000MB/s)? The prime example is SSDs, but you may also see high performance drives in RAID Systems. All SSDs will cap out on USB3.0 and require a faster connection interface to achieve peak performance, so in this instance you need Thunderbolt or USB3.1 to get the most out of that particular SSD.
When I have been asked the question of Thunderbolt Drives it has been in relation to HDDs, specifically 5600rpm HDDs which cap out around 115MB/s. Being that all modern connection interfaces exceed the 115MB/s limit of the drive itself, it doesn't matter if we are using USB3.0, Thunderbolt 1, Thunderbolt 2, USB3.1 or even Firewire 800. That drive will perform the same via any of those connections.
So for those of you that have been fooled into thinking a Thunderbolt Hard Drive will perform better or offload faster, think twice and ask if it's got an SSD inside. If not, like in most circumstances, being Thunderbolt won't make a difference at all.
MERELY A GLIMPSE
For some this may seem like an information overload, particularly when it gets technical. But this is merely a glimpse down the rabbit hole. In order to understand on an even deeper level, there are many other facets that need to be explored. I'll make brief mention of them below as reference for anyone who may want more information. Rest assured, these will be covered in-depth in a future blog post.
- Power Delivery is important. Most hard drives will suffice on bus power (5W-12W) but some will require more power from an external source. All explanations above are based on adequate power delivery to the hard drive.
- There are many flavours of HDD. 2.5" and 3.5", 5400RPM through to 7200rpm. These form factors and components have an impact on speed. In this article we are primarily talking about 5600RPM HDDs which is what you will see in most portable hard drives off the shelf.
- SSDs come in many flavours as well. There are SATA SSDs which we discussed in this article, but also the newer M.2 SSDs and PCIe SSDs, both of which deliver significant speed improvements.
- The concept of connection interfaces is quite in-depth. We need to address M.2 and PCIe Internal Connections as opposed to just SATA which we discussed here. In terms of External Connection Interfaces the differences in power delivery, different connectors and ports as well as the difference between Theoretical Speed and Actual Speed all needs to be discussed.
- What happens to the bridge after the connection to your computer? Your USB-C or Thunderbolt 3 Port connects directly to your computers motherboard which has it's own limitations in terms of PCIe Lanes and how it allocates speed and resources. While this rarely is a factor in the throttling of hard drive speeds it's valuable information that you should know.
So I leave you with a new understanding of hard drive theory and hopefully with some practical knowledge that you can apply to your work. As I said, this is the tip of the iceberg. If there is anything you want to know specifically or in more detail, please let us know in the comments section below.