Every storage medium fails. The useful question isn't which one lasts longest — it's how each one fails, how much warning you get, and what schedule keeps your data alive across a timespan longer than any single device.
The short answers
| Medium | Realistic working life | Warning before failure | Unpowered storage |
|---|---|---|---|
| Spinning hard drive | 3–5 years active | Often some | Reasonable, years |
| SSD (consumer) | 5+ years, usually endurance-limited far beyond typical use | Usually little | Poor for long periods |
| USB stick | 1–3 years of real use | Almost none | Poor |
| SD card | 2–5 years, fewer with heavy writing | Little | Poor |
| Writable CD/DVD | Highly variable, sometimes only a few years | None | Unpredictable |
| Archival optical disc | Rated for decades | None | Good |
| LTO tape | 15–30 years rated | N/A | Good, needs a drive |
The variation within each row is larger than the differences between rows. Treat these as orientation, not prediction.
Spinning hard drives
How they fail: mechanically, usually. Bearings, motors, read heads. Sometimes gradually with bad sectors accumulating, sometimes suddenly.
The failure curve isn't a simple wear-out. Large-scale data from operators running thousands of drives consistently shows elevated failure in the first months — manufacturing defects surfacing — then a lower steady rate for several years, then a rising rate as drives age past the four or five year mark.
That first-months bump is why a new drive isn't automatically safer than a two-year-old one, and why running a new backup drive alongside the old one for a few weeks is sensible.
Warning signs: clicking, grinding, or beeping; slow transfers; files that intermittently won't open; the drive disappearing and reappearing; errors during backup. Any of these means replace now.
Health monitoring exists — drives report internal statistics, and both operating systems and various free tools can read them. It's an imperfect predictor: many failures give no advance warning in the data. Treat a warning as reliable and the absence of one as meaningless.
Unpowered storage: reasonable. A drive in a drawer for five years will usually still read, which is why hard drives beat flash for archives.
Replacement schedule: every three to five years for active use. For archive drives that sit unused, plug in annually to verify and replace every five years regardless.
Solid state drives
How they fail: the memory cells wear out with writes, and the controller can fail outright.
Endurance is rated in terabytes written. For normal use — documents, browsing, media — modern consumer SSDs have endurance far exceeding what anyone will write in the drive's practical lifetime. You'll replace it for being too small or too slow long before you wear it out.
Heavy write workloads — video editing scratch disks, databases, extensive virtualization — are the exception, and those should use drives rated for it.
Warning signs: usually none. This is the important difference. SSDs frequently work perfectly and then don't. Some drives enter a read-only state when they detect wear, which is the best case. Many just stop.
Recovery is harder than with spinning drives, partly because of how the controller manages data internally. Professional recovery from a failed SSD is less often successful.
Unpowered storage: poor for long periods. Stored charge dissipates over time, faster in warmer conditions and faster on a heavily-worn drive. An SSD left unpowered for years is not a safe archive.
Practical implication: SSDs are excellent as working drives and poor as long-term shelf storage. Use them for the system drive and for portable working storage; use spinning drives for archives.
Flash: USB sticks and memory cards
Covered in more depth elsewhere, and the summary:
USB sticks are the least reliable storage anyone uses regularly. Cheap controllers, cheap memory, physically fragile. Treat as disposable transit media.
SD cards from reputable manufacturers are better, and cards used in cameras get heavy write cycling and wear out. Replace every few years and immediately on the first error.
Both lose data when unpowered for extended periods. Anything sitting on a USB stick in a drawer since 2019 should be copied off today and verified.
Counterfeits are widespread in the memory card market, reporting a larger capacity than they contain. Buy from trusted sources and test new cards before relying on them.
Optical discs
Ordinary writable CDs and DVDs are far less durable than their reputation. The dye layer degrades, and the rate depends on the dye chemistry, manufacturing quality, storage conditions, and light exposure. Some burned discs from the early 2000s read fine; others from the same era are unreadable. There's no way to tell without trying.
Pressed discs — commercially manufactured, not burned — are more stable, because the data is physically stamped rather than chemically written.
Archival-grade optical media exists, using an inorganic recording layer rather than organic dye, and is rated for decades. It's genuinely stable and it's expensive per gigabyte.
The bigger problem is drives. Optical drives are disappearing from computers. A perfectly readable disc is useless without something to read it in, and that's an accelerating problem.
If you have data on discs: copy it to hard drives now, while drives to read them still exist. This is one of the more urgent migrations most people are quietly overdue on.
Tape
Not relevant to most households, worth knowing about.
LTO tape is rated for decades of storage, costs very little per terabyte at scale, and is inherently offline — which makes it excellent against ransomware. The drives are expensive, so it only makes economic sense above a substantial volume.
It shares the optical problem in a milder form: you need a compatible drive, and tape generations have limited backward compatibility.
The thing that actually determines longevity
No medium is permanent. Data survives by being copied forward.
A photo from 1998 that's still readable today has probably lived on a hard drive, then a different hard drive, then possibly a disc, then another hard drive, then a cloud service. The medium changed several times. The data survived because someone kept moving it.
This reframes the whole question. You're not choosing a medium that will last thirty years — you're building a process that migrates data across media every few years.
The process:
- Two copies, minimum, on different devices, ideally in different places
- Verify annually — plug in each drive, open a few files, confirm it reads
- Replace on a schedule — every three to five years, regardless of apparent health
- Migrate before formats or connectors become obsolete — this is what caught everyone with optical discs and floppy disks
- Keep a manifest of what's on each drive, so you know what you'd be losing
Step three is the one people resist because the drive still works. That's exactly why it's the right time to replace it — copying from a healthy drive is easy, copying from a failing one is not.
Format obsolescence, the slower threat
Media outlasting the ability to read it is a recurring pattern. Floppy disks, Zip drives, optical media, and various proprietary formats have all followed it.
Current things to watch:
Connectors change. Older interfaces are disappearing from new machines. A drive you can't plug in is a drive you can't read.
File formats become unsupported. Proprietary formats from discontinued software are a real risk. Save anything important in an open format alongside the original — PDF for documents, standard image formats for pictures, plain text or CSV for data.
Encryption becomes unreadable. An encrypted archive whose software no longer runs, or whose password is lost, is gone regardless of the medium's condition.
Cloud services close. A different kind of obsolescence, and the same lesson: keep a copy you control.
The replacement schedule
Annually:
- Plug in every archive drive, open files, confirm it reads
- Check the health status of active drives
- Note the age of everything
Every 3–5 years:
- Replace active drives, backup drives, and archive drives
- Copy forward to the new drive, verify, then dispose of the old one securely
Whenever a warning appears:
- Replace immediately. A drive giving warning signs is a drive on borrowed time.
Whenever a connector or format starts disappearing:
- Migrate now, while you still can. Waiting until the last drive with the right port dies is how archives are lost.
The uncomfortable summary
If your only copy of anything is on a device more than five years old that you haven't plugged in during that time, it may already be gone and you wouldn't know.
Check it this week. That's the actionable version of everything above.
Next in this series: How to Connect and Use an External Drive on Any Device