A portable external hard drive in regular use typically lasts 3 to 5 years. Desktop hard drives that sit still on a shelf often run longer, and data center drives tracked by Backblaze mostly make it past four years and often past six. External SSDs don't wear out from age the way spinning drives do, but an SSD left unplugged in a drawer can slowly lose data, and the minimum the industry standard requires is only about a year once a consumer SSD is worn out.
None of these numbers tells you when your drive will fail. Plan on any single drive dying without warning, and keep the files on at least two of them.
TL;DR: Portable HDDs: about 3-5 years in regular use; drops, heat, and bus power are what kill them. Desktop HDDs: often 5+ years; Backblaze's data center drives failed at 1.36% per year in 2025, and about 90% lasted four years in its longer analysis. SSDs: rated by writes, which most backup drives never use up, but unpowered SSDs can lose data over time (the JEDEC client spec requires one year at 30°C for a worn drive). For a drive in a drawer, plug it in at least once a year, check the files, and replace it around year five.
How Long Do Hard Drives Last, by Type
| Drive | Typical lifespan | What usually ends it |
|---|---|---|
| Portable HDD (2.5", bus powered) | 3-5 years of regular use | Drops and knocks while running, heat, weak USB power, cheap enclosures |
| Desktop HDD (3.5", own power supply) | 5+ years | Mechanical wear (motor, heads), power supply or enclosure failure |
| Portable SSD | Usually outlasts its usefulness when powered regularly | Controller failure, connector damage, data loss if left unpowered for long periods |
| Internal Mac SSD | The life of the Mac in most cases | Write wear only matters under very heavy workloads |
These are typical ranges, not guarantees. The same model can last ten years in one home and die in eight months in another.
What the Failure Data Says
The best public data on hard drive lifespans comes from Backblaze, which runs several hundred thousand drives in its data centers and publishes the failure numbers every quarter.
- 2025 annual failure rate: 1.36% across 344,196 drives, down from about 1.55% in 2024 (2025 Drive Stats report). Roughly 1 in 70 drives failed during the year.
- Lifetime failure rate: 1.30% across all the drives Backblaze has run.
- Survival over time: in Backblaze's analysis of drive lifespans, about 90% of its drives lasted four years and 65% were still running after six. Failure rates stayed low for the first three and a half years, then rose quickly.
- Bad models exist. Single models have run at 6-10% failures per year while the fleet sat near 1%.
Two cautions before applying this to the drive on your desk. Backblaze's drives are enterprise models in climate-controlled racks, never dropped, never unplugged mid-copy. And they spin all day; a home archive drive mostly sits switched off. The data is a good guide to how long the mechanism lasts. It says nothing about the knocks, heat, and power problems that kill portable drives.
Why Portable External Drives Die Sooner
A 2.5-inch portable hard drive is the same kind of spinning disk, in a much harder life:
- It gets moved while running. The read heads fly nanometers above the platter. A knock while the drive is spinning can crash them into it. This is the most common way portable drives die.
- It gets warm. Small enclosures with no fan run hot during long copies, and heat shortens the life of the motor and electronics.
- It runs on USB power. Unpowered hubs and long cables can starve the drive, which shows up as random disconnects. Each unexpected disconnect during a write is a chance to corrupt the filesystem.
- The enclosure fails first. Often the disk inside is fine and the USB bridge board dies. That's one reason a "dead" drive is sometimes recoverable.
Desktop drives with their own power supply avoid most of this, which is why they're the better choice for an archive that doesn't travel. Our external drive guide covers which to buy for which job.
How Long Does an SSD Last?
SSDs wear out by writing, not by age. Each flash cell survives a limited number of writes, and drives are rated in terabytes written (TBW). Internal 2TB SSDs are commonly rated for over a thousand terabytes written, and portable SSDs use the same kind of flash (most portable models just don't publish a rating). A backup drive that gets a few hundred GB a month won't come close in its lifetime.
What matters more for backups is what happens when the SSD is unplugged. Flash memory holds data as an electrical charge, and that charge leaks slowly. A powered SSD refreshes it in the background; an unpowered one can't. The JEDEC standard for client SSDs (JESD218) requires a drive to hold data for one year unpowered at 30°C, measured once the drive has used up its rated write endurance. Retention roughly halves for every 5°C warmer the drive is stored.
In practice, a new or lightly used SSD keeps data much longer than a year. The point is that an SSD in a hot drawer is a worse long-term archive than people assume, and a worse one than a hard drive, which stores data magnetically and doesn't leak charge.
How Long Does Data Last on an Unused External Drive?
A hard drive in a cool, dry drawer keeps its data for many years. The risk is mechanical: lubricants settle and motors that haven't spun in years sometimes don't start. An SSD has the charge-leak problem above.
For any drive you rarely use:
- Plug it in at least once a year and let it run for a while. For an SSD, an hour or two connected gives the controller time to refresh.
- Check the files, not just the drive. Open a few, or better, compare them against a list of checksums made when you copied them. A drive that mounts can still hold damaged files; our guide to bit rot on Mac shows how to check.
- Store it cool and dry, away from magnets, upright for desktop drives, in a padded case for portables.
- Keep a second copy somewhere else. A drive in a drawer is one copy. If it's the only one, it isn't a backup.
Signs an External Hard Drive Is Failing
- New clicking, grinding, or beeping noises
- The drive disconnects or remounts on its own
- Copies slow to a crawl or fail partway
- Finder freezes when the drive is connected
- Disk Utility's First Aid reports errors it can't repair
If you notice any of these, copy off the files that exist nowhere else first, before running repairs. Our drive not showing up guide covers what to do when it won't mount at all.
When Should You Replace an External Hard Drive?
Replace a drive when it shows any warning sign above, and plan to move a working archive drive's contents to a new drive around year five. Moving it is cheaper than recovering it. Hard drives still cost less per TB than anything else (see our cheapest storage per GB breakdown), so a fresh 8TB drive every few years is a small cost against the files on it.
When you migrate, check the copy before wiping the old drive. If you're merging several old drives onto one, run them through our free duplicate file finder first, so the same shoot doesn't land on the new drive three times. That's also a good moment to note which projects moved where, because three migrations later nobody remembers. Tracking that is part of what Tusk does, if you'd rather not keep the list by hand.
FAQ
A portable external hard drive in regular use typically lasts 3 to 5 years. Desktop external drives with their own power supply often last 5 years or more. Backblaze's data center drives failed at 1.36% per year in 2025, and about 90% lasted four years in its lifespan analysis, but portable drives face drops, heat, and power problems those drives never see.
SSDs wear out from writes, and 2TB SSDs are commonly rated for over a thousand terabytes written, far more than a backup drive uses. The bigger risk for backups is storage without power: the JEDEC client SSD standard only requires a worn drive to keep data for one year unpowered at 30°C. Plug SSDs used as archives in at least once a year.
A hard drive is the better choice for long-term storage you rarely plug in. It stores data magnetically and doesn't leak charge while unpowered, and it costs much less per TB. SSDs are better for drives that travel and get used often, because they have no moving parts to damage when knocked.
A hard drive stored cool and dry usually keeps its data for many years, but its motor can fail to spin up after long storage. An unpowered SSD slowly loses charge, so data retention depends on wear and temperature. For either, plug the drive in once a year, check the files, and keep a second copy elsewhere.
Clicking or grinding sounds, random disconnects, very slow or failing copies, Finder freezing when the drive is connected, and First Aid errors it can't repair. If you see any of these, stop using the drive for anything except copying off files that exist nowhere else.