Today’s Question: You suggested recently that it would be OK to keep your Lightroom [Classic] catalog on an external hard drive, but that if you do it is recommended to get the “fastest external hard drive available”. How does one go about finding such a hard drive?
Tim’s Quick Answer: As a general rule a top-rated bus-powered SSD external drive is going to provide great performance. Two of the drives I would put at the top of my list in terms of performance are the Samsung T5 (https://timgrey.me/samsungt5) and the G-Drive Mobile (https://timgrey.me/gdrivessd).
More Detail: Keeping your Lightroom Classic catalog on an external hard drive provides greater flexibility when you need to move between more than one location with your Lightroom catalog. For example, you could use an external hard drive for your catalog both on your desktop computer at home and on your laptop computer when traveling. The same would hold true if you split your time at two locations during the year.
Speed is the first priority in this type of scenario, which in turn means that an SSD (solid state drive) is generally going to be your best option. I also very much prefer opting for a bus-powered drive, so that an additional power adapter is not required. That also helps to streamline your workflow when moving between two or more locations.
Two of the hard drives I currently put among those I would most highly recommend for fast storage on the go are the Samsung T5 SSD (https://timgrey.me/samsungt5) and the G-Drive Mobile (https://timgrey.me/gdrivessd). The G-Drive option also provides the benefit of being quite rugged, and from that standpoint might be the drive I would recommend most highly.
It is important to make sure your computer provides a connection that enables the fastest speed possible from the drive, based on the drive specifications. For example, both of the drives mentioned above require a USB 3.1 connection for fastest performance. I think it is also worth keeping in mind that the theoretical maximum speed for the interface (such as USB 3.1) does not directly translate to the speed of the hard drive.
For example, the USB 3.1 specification supports data transfer speeds of up to 1.25 GB per second. In reality, the drives listed above will typically give you sustained write speeds of about 500 MB per second, or about half the potential speed of the USB 3.1 specification. Also keep in mind that actual performance can vary considerably based on how the data is actually being transferred.