External SSD vs HDD for Backup: An Unpowered SSD Is Only Specified for 1 Year

Short answer: for a backup that stays plugged in or travels with you, buy a portable SSD; for a large archive or a copy that lives in a drawer or a safe-deposit box, buy a hard drive; and for anything you cannot replace, buy both. The detail most buyers never see is that the JEDEC standard behind consumer SSD endurance ratings, JESD218, only requires a worn client SSD to hold data for 1 year without power at 30°C. That is not a reason to avoid SSDs. It is a reason not to treat one as a time capsule.

First, decide what kind of backup this is

“Backup drive” describes at least three different jobs, and the right hardware differs for each:

• The connected backup. Plugged into your computer or dock, updated hourly or daily by Time Machine, File History or a backup app. It is powered constantly, so retention is irrelevant. Speed and silence matter.
• The rotating or travel backup. Carried in a bag, connected for an hour a week, handled a lot. Shock resistance matters most.
• The cold copy. Written once or twice a year and stored away from the computer — ideally away from the house. Cost per terabyte and unpowered behavior matter most.

Almost every disagreement about SSD versus HDD comes from people talking about different jobs.

What the JEDEC retention spec actually says

JEDEC is the semiconductor industry’s standards body, and its JESD218 standard defines how SSD endurance (the TBW figure on a spec sheet) is rated. As part of that definition it sets a data-retention requirement, explained in JEDEC’s own presentation on the standard:

Three qualifications keep this from being misread:

1. It is measured at the end of rated endurance. The requirement is that after the drive has absorbed all the writes it is rated for, it must still hold data for that long. NAND flash stores data as trapped charge, and worn cells leak charge faster than fresh ones. A backup SSD that has been written a few dozen times is nowhere near that condition.
2. It is a floor, not a forecast. Manufacturers must meet it; most drives exceed it. But no consumer SSD maker publishes a longer guaranteed figure, so 1 year is the only number anyone has actually promised.
3. Temperature works against you. Charge leaks faster when the drive is stored warm. A drive in a climate-controlled closet is in a different situation from one in a car glovebox or an attic in July.

Does plugging the drive in “recharge” it? Partly. A powered SSD’s controller can detect weakening cells and rewrite them, but how aggressively it does so is firmware-specific and undocumented, and a drive connected for two minutes will not scan itself end to end. There is no JEDEC or manufacturer figure for how often to power up an archived SSD. Connecting it a few times a year and running a full verification pass — which forces every block to be read — is cheap insurance rather than a guarantee.

Hard drives age too, just differently

Magnetic recording does not rely on trapped charge, so a hard drive’s bits are not on the same clock. That makes an HDD the more conservative choice for a copy that will sit for years. It does not make it archival:

• Mechanical parts age. Bearings, lubricant and the head-parking mechanism are what fail on drives that sit, and a drive can spin up fine for a decade or refuse on year six. No consumer hard drive carries a shelf-life rating; the 2- to 5-year warranties are not storage promises.
• Failure rates in service are low but not zero. Backblaze, which publishes failure statistics for the several hundred thousand drives in its data centers, reported an annualized failure rate of 1.36% for 2025. Those are 3.5-inch drives in vibration-controlled racks, not portable drives in backpacks, so treat it as a best case.
• Drops are the real killer. A spinning 2.5-inch drive knocked off a desk while running can be destroyed instantly. An SSD in the same fall will almost certainly survive.

The honest summary is that neither technology is an archive medium. A copy you have not checked is a copy you are hoping exists.

Cost per terabyte: do the division yourself

Storage prices moved a lot through 2025 and 2026, flash especially, so any figure printed here would be stale within weeks. The method does not change: divide the price by the capacity in TB and compare within the same week.

What has held steady for years is the ordering:

Two practical consequences. If you are protecting more than about 4 TB — a photo or video library, several family computers — a desktop hard drive is usually the only option that is not painful to buy twice, and buying twice is the point of backup. And if you are protecting under 1 TB, the absolute price gap between a portable HDD and a portable SSD is small enough that the SSD’s durability and speed are easy to justify.

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Speed: it matters for the first backup and for the restore

A portable hard drive manages somewhere around 100–140 MB/s on large files and far less on many small ones. A mainstream portable SSD on a 10 Gbps USB port is rated around 1,000 MB/s — Samsung rates the T7 at up to 1,050 MB/s. In round numbers:

Two caveats. Incremental backups are small, so day to day you will rarely notice the difference; speed pays off on the first run and on the day you restore, which is the day you are already having a bad time. And SSD box speeds are burst figures: once the fast cache fills, sustained writes fall, sometimes to a third of the headline. We covered that cliff in the portable SSD specs nobody prints on the box, and the interface side in NVMe enclosure speed tiers.

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Shock, heat and travel

An SSD has no moving parts, and the ruggedized models publish figures: Samsung rates the T7 Shield at IP65 for dust and water and for drops of up to 3 meters. A portable hard drive has no comparable rating for a fall while spinning; the rubber bumpers on “rugged” HDDs protect the case more than the platters.

For a drive that lives in a laptop bag, this settles the question on its own. The one SSD travel caution is heat: do not leave it in a parked car in summer. Heat is what shortens flash retention, and a closed car is the hottest place most electronics ever see.

Check rugged IP65 portable SSDs on Amazon

SMR vs CMR: the hard-drive spec that is rarely on the box

Conventional magnetic recording (CMR) writes tracks side by side. Shingled magnetic recording (SMR) overlaps them like roof shingles to fit more data on a platter, which means changing one track requires rewriting its neighbors. Drives hide this behind a CMR-style cache zone and tidy up when idle.

The issue became public in 2020, when Western Digital confirmed that its 2 TB–6 TB WD Red NAS drives used device-managed SMR without saying so, after users reported RAID rebuilds failing or taking days; WD now publishes which models are which. For external drives the picture is murkier: makers seldom state the recording type, and high-capacity 2.5-inch portable drives are widely SMR because that is how 4 TB and 5 TB fit in a slim case.

For backup, that is mostly acceptable:

• Sequential backup writes are SMR’s best case. Nightly incrementals give the drive idle time to reorganize.
• A huge first backup is its worst. Once the cache zone fills, write speed can fall to a few tens of MB/s. Let it run overnight; it is slow, not broken.
• Do not put SMR drives in a RAID or NAS. A rebuild is sustained writing with no idle time. If that is your plan, read RAID enclosure vs NAS and buy drives whose spec sheet says CMR.

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The 3-2-1 rule beats any single drive

CISA, the US Cybersecurity and Infrastructure Security Agency, recommends the 3-2-1 rule: 3 copies of important data, on 2 different types of media, with 1 copy off-site. It exists because the failures that actually destroy data are not drive failures. They are fire, theft, a burst pipe, a power surge that takes out the computer and the drive plugged into it, and ransomware that encrypts every disk it can reach — which is why CISA’s ransomware guidance separately insists on a backup that is kept offline.

This is also why SSD versus HDD is a smaller decision than it looks. Using both gets you the “two media types” almost for free, and their weaknesses do not overlap: the SSD is the fast, drop-proof daily copy, and the hard drive is the cheap, large copy that does not mind sitting unplugged.

A home setup that satisfies the rule:

1. The computer itself (copy 1).
2. A portable SSD or desktop HDD at the desk, backing up automatically (copy 2, second medium).
3. A cloud backup service, or a second hard drive refreshed monthly and kept at work or at a relative’s house (copy 3, off-site and, in the drive’s case, offline).

Encrypt anything that leaves the house. BitLocker To Go on Windows Pro and the “encrypt backups” option in Time Machine are built in and cost nothing — but a lost password means a lost backup, so store it in your password manager.

Which to buy, by use case

Maintaining a backup drive of either kind

• Test a restore. Twice a year, pull one old file back from the backup and open it. This is the only test that counts.
• Read the health data. Drives report SMART attributes; free tools such as CrystalDiskInfo on Windows, or Disk Utility’s SMART status on a Mac, will show reallocated sectors on an HDD or percentage-used on an SSD. Rising reallocated-sector counts mean replace now.
• Eject before unplugging. Pulled cables during a write are the most common way portable drives of both types get corrupted.
• Replace on a schedule. Storage is cheaper than recovery. Rotating a backup drive out after roughly five years, while it still works, is sound practice; retire the old one to the off-site role rather than the trash.
• Store cool and dry. It helps both types and is the one retention factor you control.

Where this article stops

We do not lab-test drives, and no one can tell you how long your specific drive will hold data unpowered; the JEDEC figure is a minimum for worn flash, not a measurement of any product. This guide also does not cover true archival media such as M-DISC or LTO tape, professional data recovery, or business retention requirements. If the only copy of something important is on a drive that has started clicking or disappearing, stop powering it and contact a recovery service — every spin-up can make it worse.

Summary

JESD218 requires a client SSD at end of life to hold data for 1 year unpowered at 30°C, which is a worst-case floor and the only retention figure anyone guarantees. It makes an SSD a poor drawer archive and takes nothing away from it as a connected or travel backup, where its speed and shock resistance win clearly. Hard drives cost far less per terabyte and tolerate sitting unplugged, but drop badly and age mechanically; SMR models are fine for backup and wrong for RAID. Whichever you buy, the 3-2-1 rule — three copies, two media, one off-site and offline — matters more than the medium, and a restore you have actually tested matters more than either.

More home and gadget guides at GadgetHub English.

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