CONNECTION INTERFACE

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.