Gadgets & Devices
A jargon-free guide to choosing an external drive, comparing SSD and hard disk options, capacity, and ports so you pick the right storage for your needs.
Buy a portable SSD if the drive will travel with you or hold anything you open daily; buy a desktop hard disk if you want the cheapest possible space for backups and archives that mostly sit still. Every other decision — capacity, port, encryption, file format — falls out of that one choice, and getting it wrong is exactly what leaves people with a drive that crawls or a backup that quietly fails.
There are three real categories on the shelf, not two, and they price out very differently.
A portable SSD (Samsung T7, Crucial X9, SanDisk Extreme, WD My Passport SSD) has no moving parts, weighs around 40-60 grams, and survives being dropped in a bag or onto a hard floor. A SATA-based one reads and writes up to about 1,050 MB/s; an NVMe model (Samsung T9, Crucial X10 Pro) can hit 2,000 MB/s or more. Expect to pay roughly three to five times per terabyte what a spinning drive costs.
A portable hard disk (WD My Passport, Seagate Expansion) is a 2.5-inch, 5,400 RPM mechanical drive. It's USB-powered and pocket-sized, but it tops out near 5 TB and moves data at only 120-140 MB/s. It's also the most fragile option: a drop while the platter is spinning can kill it.
A desktop hard disk (WD Elements/My Book, Seagate Backup Plus Hub) is a 3.5-inch drive that needs its own power adapter. It goes up to 20-24 TB, runs 180-260 MB/s, and has by far the lowest cost per terabyte. It's meant to live on a desk, not in a bag.
Most people buy on price alone, end up with a slow 2.5-inch portable HDD as their main working drive, then wonder why copying a folder of photos takes ten minutes. If you touch the files often, the SSD's speed and shock resistance earn their premium. If the drive just parks a video library or nightly backup, the desktop HDD's cheap bulk wins. Many people rationally own both.
Many budget external hard drives use SMR (shingled magnetic recording), which overlaps data tracks to cram in more capacity. SMR is fine for write-once archives but chokes on sustained or random writes, sometimes dropping to 20-40 MB/s mid-transfer. Drives built for backups and NAS use CMR (conventional recording) instead. Manufacturers rarely print this on the box, so search the exact model number plus "SMR" before buying if steady write speed matters to you.
Buying too little is the most common regret, so size for where your data will be in two years, not where it is today.
Start with the real number: on Windows, right-click your drive in File Explorer and choose Properties; on a Mac, open Apple menu > About This Mac > More Info > Storage. Note how full it is, then estimate growth. This is where file type matters enormously:
Pick the size you think you need and step up one tier — 2 TB instead of 1 TB, 8 TB instead of 4 TB. There's a technical reason beyond convenience: keep at least 10-15% free on an SSD so its controller has room for wear-leveling and garbage collection. A drive crammed to 99% both slows down and, on an SSD, wears faster.
For a backup drive specifically, aim for 1.5 to 2 times the data you're protecting. Backup software like Windows File History or macOS Time Machine keeps multiple versions over time, and Time Machine will happily consume the whole drive with historical snapshots. A backup disk that's already near full can't keep a useful history.
A 2,000 MB/s SSD plugged into the wrong port runs at a quarter of its speed. The drive, the cable, and your computer's port all have to support the same standard — the chain runs at its slowest link.
Here's what the USB labels actually mean:
To make it concrete, copying a 50 GB video file takes roughly 110 seconds over USB 3.2 Gen 1, but around 50 seconds over Gen 2. For a mechanical hard disk, none of this matters — the drive maxes out at ~200 MB/s, so even old USB 3.2 Gen 1 has headroom to spare. Don't pay for a fast port on a slow drive.
Newer laptops use the small, reversible USB-C connector; many still have the rectangular USB-A. A USB-C drive that ships with only a USB-C cable is useless on a USB-A-only machine without an adapter. Also note that a USB-C port is not automatically fast — plenty of laptop USB-C ports are wired for only 5 or 10 Gbps, and only ports marked with the Thunderbolt lightning bolt guarantee 40 Gbps.
Straight out of the box, most drives are formatted NTFS (Windows) or exFAT. This trips people up constantly:
If the drive will only ever touch one operating system, use that OS's native format for reliability and features. If it moves between a PC and a Mac, format it exFAT.
For anything sensitive, encryption is the difference between a lost drive and a data breach. BitLocker To Go (Windows Pro/Enterprise) or VeraCrypt (free, cross-platform) encrypt any drive with AES-256, so a thief who plugs it in sees only scrambled data. Some drives include hardware encryption with a built-in keypad, which is convenient but ties you to that hardware. Skip encryption for a drive of movies you don't mind losing.
If the drive travels rough, look at ruggedized models (LaCie Rugged, Samsung T7 Shield) with IP-rated water and dust resistance and rubber bumpers. Check the warranty too: most externals carry 2-3 years, and a longer warranty is a rough proxy for the manufacturer's own confidence.
One rule overrides all of this: every drive eventually fails, SSD and hard disk alike. Never let a single external drive hold your only copy of anything. Follow the 3-2-1 rule — three copies of important data, on two different types of media, with one kept offsite (or in cloud storage). An external drive is one leg of that plan, never the whole thing.
They're more durable against drops and vibration because nothing spins, which is why they're better for travel. But SSDs have finite write endurance and can fail suddenly with little warning, while a failing hard disk often gives audible clicking or slowdowns first. Neither is a substitute for a real backup.
Yes — format it as exFAT, which both operating systems fully read and write. Avoid NTFS (Windows-write-only on Mac) and APFS (Mac-only). Just always eject the drive before unplugging, since exFAT isn't journaled and is more vulnerable to corruption.
Almost always a weak link in the chain: a USB 3.2 Gen 1 port, an old cable, or an SMR hard disk slowing down on sustained writes. Confirm the drive, cable, and port all support the same speed standard, and plug into a port marked for 10 Gbps or Thunderbolt rather than a random hub.
For a desktop hard disk used as a backup target, yes — that's what it's built for, though enabling sleep for the drive reduces wear. Leaving a portable drive dangling from a laptop invites a knock that can damage the port or a spinning HDD. Either way, eject before unplugging to avoid corrupting files mid-write.
Lena writes about phones, laptops, and gadgets for people who want good advice, not a spec-sheet recital. She's blunt about what's worth the money, patient with setup headaches, and a firm believer in making your devices last longer.
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