External

Category overview

External hard drives add storage to a PC or notebook in minutes, with no internal installation. They are the simplest way to keep a backup, hold a media library that does not have to live on the main drive, or move large amounts of data between machines.

What this category covers

Desktop external HDDs, which are larger units with their own power supply and the highest available capacities; portable external HDDs in 2.5-inch form factor, which are bus-powered and travel easily; and ruggedized portable drives with reinforced enclosures for fieldwork.

How to choose an external hard drive

Desktop or portable

Desktop external drives offer higher capacities and are the right choice for fixed backup and archive use. Portable drives are smaller, draw power from the USB port, and travel without an extra power brick. The trade-off is capacity: portable drives top out lower, and the largest portable drives are slower than equivalent desktop drives.

Plan around the USB connection

The drive's interface limits its speed to that of the host port. A USB 3.x desktop drive on a USB 2.0 port runs at USB 2.0 speed. Verify that the most-used host has the right USB version and that the supplied cable matches.

Backups need more than a single drive

An external drive used as the only backup is one drop or one failure away from data loss. For backups that matter, keep at least two copies on different drives, and keep one of them off-site. The 3-2-1 rule applies to external drives as much as to any other backup medium.

Key features to compare

Capacity per drive

Portable external HDDs run up to about 5 TB. Desktop external HDDs go well beyond, with 12 to 24 TB models common. Higher capacities cost less per gigabyte but mean more data on a single point of failure.

Drive speed and cache

Most portable HDDs run at 5400 RPM. Desktop drives may run at 5400 or 7200 RPM with larger cache. For backup workloads, the difference matters mainly during the initial full backup; after that, incremental backups are usually small enough that drive speed is not the bottleneck.

Software and encryption

Some drives come with backup software or hardware encryption. Many users choose to ignore the bundled software and use a backup tool of their choice or the operating system's built-in tools. Hardware encryption is a useful feature for portable drives carrying sensitive data.

What to check before buying

• Will the drive be fixed in one place or carried frequently?
• Is the capacity enough for both the current data and the next year of growth?
• Does the host PC have a USB port that matches the drive's rated speed?
• Is the drive part of a single backup, or one of several copies in a proper backup plan?
• Does the data being stored need hardware encryption?

Frequently asked questions

Is an external SSD better than an external HDD?

For speed, durability and noise, external SSDs are clearly better. For capacity at low cost, external HDDs still win above a few terabytes. The right choice depends on the use: SSDs for active working data and travel, HDDs for backups and archives where speed is less important.

Why does my external drive disconnect when I plug in another USB device?

This is usually a power issue on bus-powered drives. The host USB port cannot supply enough current when several devices share it. Move the drive to its own port directly on the host, or use a powered USB hub.

Can I leave a desktop external HDD running constantly?

Most desktop external HDDs are designed for intermittent use. Leaving one running 24/7 is possible but shortens the drive's expected life and is harder on the bridge electronics in the enclosure. For continuous use, a NAS (Network Attached Storage) with proper drives is a better long-term solution.

Should I format an external HDD before first use?

Most drives ship pre-formatted in exFAT or NTFS and work out of the box. For a clean start, especially when moving between Windows and macOS, reformatting to the desired file system is straightforward and only takes a few minutes for a quick format.

How do I dispose of an old external drive securely?

For drives that held sensitive data, a full overwrite or a manufacturer's secure erase is the minimum step before disposal. For drives that will not be reused, physical destruction (drilling through the platters in a HDD) is the most reliable approach. Encrypted drives are easier to retire safely because deleting the encryption key effectively renders the data unreadable.