Dan Goodwin, writing for Ars Technica:

For almost five months—possibly longer—the Spotify music streaming app has been assaulting users’ storage devices with enough data to potentially take years off their expected lifespans. Reports of tens or in some cases hundreds of gigabytes being written in an hour aren’t uncommon, and occasionally the recorded amounts are measured in terabytes. The overload happens even when Spotify is idle and isn’t storing any songs locally.

And:

Spotify officials hadn’t responded to Ars questions more than two days after they were sent. According to comments left in the Spotify forum in the past 24 hours, the bug has been fixed in version 1.0.42, which is in the process of being rolled out. The update remains unavailable to many users, this reporter included. And that means Spotify’s drive-assaulting behavior continues unabated for many.

Sounds like, if you use Spotify, get the update or disable it.