Portable versus desktop SSD external hard drives

$90 for a 5TB SSD? That doesn't sound right.

The only thing I could find on Amazon that is 5TB and $90 is the following and it is not an SSD: https://www.amazon.com/Seagate-Portable-External-Hard-Drive/dp/B07VS8QCXC/ref=sr_1_4?keywords=amazon%2B5tb%2Bdrive&qid=1574633918&s=pc&sr=1-4&th=1

Portable hard disk drives might be more rugged than desktop drives. Or they might not be.

Portable drives are physically generally smaller than desktop drives. Or they might not be.

Portable drives and desktop drives both work fine with a Mac. Usually.

SSDs are generally physically more robust than are hard disk drives.

A five terabyte hard disk drive will store roughly five times a one terabyte hard disk drive. Whether that matters to you depends on your current and near-future storage requirements. Most folks only accumulate data, though at differing rates.

Device longevity and failure rates don’t generally track by capacity, they’re usually tied to vendors and particular series of devices, and around what prices the devices are designed to sell, where cheaper devices tend to be, well, cheaper-built.

A decently-fast hard disk operates at 100 to maybe ~150 I/O operations per second, or so. Most portable and cheaper desktop hard disks are lower-RPM hard disk drive devices and are otherwise not fast devices, and variously won’t even reach that 100 figure. A recent SSD routinely operates at tens of thousands of I/O operations per second, to hundreds of thousands of I/O operations per second. That is, quality SSDs are vastly faster than hard disk drives. Whether that performance difference matters depends on your budget and your plans. Time Machine might not need an SSD for instance, but big videos or movies or working with large files might.

There’s no one-size-fits-all answer here. And requirements, budgets, and expectations will differ. Widely.

If something seems to good to be true it usually is. Congratulations on taking the time to double check your purchase!

SSDs must be powered on once in a while to refresh their internal NAND memory cells to keep the data from becoming corrupt. If you don't use the SSD all the time I would recommend getting in the habit of powering on the SSD once a month. While in theory corruption does not occur for several years I have seen reports of SSDs corrupting data in just six months if they are left without power.

Also it is nearly impossible to recover any deleted data from an SSD or from a failing SSD.

Also do not use the proprietary third party software which ships with the drive to manage the external drive. You may lose out on being able to utilize the SSD's built-in hardware encryption, but you save yourself many headaches due to compatibility issues with the third party software. Without access to the third party software you may be unable to access the contents of the hardware encrypted SSD.

Instead use macOS to manage the external drive. Make sure to erase the external drive using macOS Disk Utility since the drive may ship using the Windows NTFS file system which macOS can read, but not write. Erase the drive as GUID partition and MacOS Extended (Journaled). If you need the external drive encrypted then let macOS encypt it for you with software encryption.

Have a look at Mercury Pro Elite drives at OWC (macsales.com). Good quality, excellent customer service, Mac-centric retailer. They come in all flavors (desktop/portable), many sizes, spinning or SSD - if choosing spinning, get the 7200 rpm. Most also come with their own power supply (or an option to run it bus powered or plugged in). They are the only ones I buy.

A lot of external drives are of very poor quality. Many times it is the controller interface board which fails and not the actual hard drive. Hard drives are actually pretty good reliable devices if they are not bumped and speed is not a concern.

If your external drives were not encrypted, then you may want to try and erase them or physically destroy them.

I agree with @babowa that the Mercury Pro Elite Enclosures are really good. I have used many of them over the years. Plus you can easily replace or upgrade the drive within the enclosure unlike many other external drives. Whatever external drive you purchase, just make sure the USB cable is detachable, otherwise the drive is toast if anything happens to the cable.