Storing disconnected hard drives for years has risks: mechanical lubricants can dry up and SSDs lose electrical charge in their cells. To preserve data long-term, it is advisable to power on the units and perform data integrity checks at least once a year.
“Cold storage” seems like the ideal solution for long-term backups: disconnect the drive and store it in a cool, dry place. However, time works against it. In traditional HDDs, the lubricant on the motor spindle and bearings can solidify, causing the platters not to spin or the heads to stick to the platter (stiction). In SSDs, NAND cells retain an electrical charge that slowly dissipates without power; after years unpowered, data can become unreadable. The best practice is to periodically connect the units, read all sectors, and rewrite if necessary to refresh the charge. This detects early degradation and avoids the surprise of finding an unrecoverable backup when it is most needed.
