  The recently introduced General Data Protection Regulation (GDPR) is forcing
several companies to make significant changes to their systems to achieve
compliance. Motivated by the finding that more than 30% of GDPR articles are
related to storage, we investigate the impact of GDPR compliance on storage
systems. We illustrate the challenges of retrofitting existing systems into
compliance by modifying Redis to be GDPR-compliant. We show that despite
needing to introduce a small set of new features, a strict real-time compliance
(eg logging every user request synchronously) lowers Redis' throughput by 20x.
Our work reveals how GDPR allows compliance to be a spectrum, and what its
implications are for system designers. We discuss the technical challenges that
need to be solved before strict compliance can be efficiently achieved.
