HDDNewInternal 3.5"
Dell NWCCG 6TB 7.2K 3.5 400-AFNY, 400-AGFU, PRNR6
Capacity6 TB
InterfaceHDD
Warranty3 months
Cost / GB$0.02
$111
$18.5per TB
How long does an unpowered SSD keep its data?
SSDs are superb working drives and questionable shelf archives. Here's what the retention standard really promises, what makes flash forget, and how to store data you need in ten years' time.
Quick answer
A healthy consumer SSD stored unpowered at room temperature typically keeps data for several years, but the guarantee is much shorter: the JEDEC standard only requires one year at 30 °C for a consumer drive that has used up its rated endurance. Retention falls with heat, wear and denser NAND (QLC). SSDs are excellent working drives but a poor choice as the only copy in a cold archive — power them up at least once a year, or archive to hard drives, tape or optical discs.
Flash memory stores bits as electrical charge trapped in cells. Without power, that charge very slowly leaks away. A drive in daily use never notices, because the controller constantly refreshes and corrects data. A drive in a drawer has no such help — which is why “how long does an unpowered SSD keep data?” has a more nuanced answer than most spec sheets admit.
What the standard actually promises
The JEDEC JESD218 standard defines how SSD endurance ratings are tested. A drive meets its TBW rating only if, after that much writing, it can still retain data unpowered for a minimum period:
| Drive class | Active use temperature | Power-off storage temperature | Minimum retention |
|---|---|---|---|
| Client (consumer) | 40 °C | 30 °C | 1 year |
| Enterprise | 55 °C | 40 °C | 3 months |
Those are worst-case floors for a fully worn drive. A new or lightly used drive retains data far longer, because fresh cells hold charge much better than cells that have been through thousands of program/erase cycles. Enterprise drives trade retention for endurance by design — they are expected to stay powered in a server.
What shortens retention
- Heat. Charge leakage roughly doubles for every 5–10 °C rise in storage temperature. A drive in a hot car or attic loses data years sooner than one in a cool cupboard.
- Wear. Each erase cycle damages the insulating layer around the cell, so a heavily written drive leaks faster. Check SMART “Percentage Used” before shelving a drive (see our endurance guide).
- Bits per cell. QLC stores 16 charge levels per cell with narrow margins between them, so it tolerates less leakage than TLC, MLC or SLC.
- Write temperature. Counter-intuitively, data written while the drive is warm and stored cold retains best; written cold and stored hot is worst.
Archive media compared
| Medium | Typical unpowered retention | Main risk | Use for |
|---|---|---|---|
| Consumer SSD / flash drive | 1–10 years (wear & heat dependent) | Charge leakage | Working copies, refresh yearly |
| Hard drive (HDD) | 5–10+ years for the data | Mechanical: stuck motor, lubricant | Bulk offline backups, spin up yearly |
| LTO tape | 15–30 years | Needs a compatible drive | Large cold archives |
| M-DISC / archival BD-R | Decades (manufacturer claims longer) | Low capacity per disc | Irreplaceable photos & documents |
How to store an SSD safely
- Keep a second copy elsewhere. No single medium should be your only archive — follow the 3-2-1 rule.
- Store it cool and dry, ideally below 25 °C, in an anti-static bag.
- Power it up at least once a year and leave it connected for an hour or two. Powering alone does not rewrite every cell, so for real peace of mind read every file (a full checksum verify or a copy to another disk does this), which lets the controller detect and refresh weak blocks.
- Keep checksums (or use a filesystem/backup tool that does) so you can prove the data is intact.
For long-term archives, the economics also favour other media: hard drives and LTO tape cost a fraction as much per terabyte. Compare live prices in our hard drive, LTO tape and optical media rankings.
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Hard drives for offline backups
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HDDUsedInternal 3.5"
(Old Model) Seagate 2TB Surveillance HDD 5900RPM SATA 6.0GB/s 64MB Hard Drive (ST2000VX003)
Capacity2 TB
InterfaceHDD
Warranty3 years
Cost / GB$0.02
$39
$19.5per TB
HDDUsedInternal 3.5"
3TB 7200RPM 128MB CACHE SAS/6GB/S NO ENCRYPTION (ST3000NM0023) -
Capacity3 TB
InterfaceHDD
Warranty—
Cost / GB$0.02
$60
$20per TB
LTO-9NewTape
10-Pack Quantum LTO 9 MR-L9MQN-01 Ultrium Data Cartridge
Capacity18 TB x10
InterfaceLTO-9
Warranty—
Cost / GB$0
$900
$5per TB
LTO-9NewTape
Fuji Lto 9 - 10 Pack
Capacity18 TB x10
InterfaceLTO-9
Warranty2 years
Cost / GB$0
$900
$5per TB
LTO-9NewTape
Fujifilm Data Cartridge
Capacity18 TB
InterfaceLTO-9
Warranty—
Cost / GB$0
$92
$5.11per TB
Before you buy
SSD data retention — questions answered
Do SSDs lose data when unplugged?+
Eventually, yes, but slowly. A healthy consumer SSD kept at room temperature typically holds data for years without power. The JEDEC standard guarantees only one year at 30 °C for a consumer drive at the end of its rated endurance, and heat or heavy wear shortens that.
How often should I power on an SSD in storage?+
At least once a year. Connect it, then read every file — for example by verifying checksums or copying everything to another disk — so the controller can detect and refresh weak cells. Simply plugging it in for a minute is not guaranteed to refresh all data.
Is an SSD or HDD better for long-term archive storage?+
For unpowered archives, hard drives, LTO tape and archival optical discs are safer and cheaper per terabyte than flash. Use SSDs for working data and backups you access regularly, and always keep a second copy on a different medium.
Keep reading
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