In our system, the biggest piece of PII is email addresses. I did not work on our GDPR solution, but my understanding is we have a system where data flows into our log aggregators and email addresses (or any other PII) are scrubbed and replaced with a hash. In our persisted logs (used for analytics and all that), there is only a hash and no email address. In the event that someone needs access to the pre-hashed value, first a request must be approved, and then access granted to a lookup table. If a user has requested we remove their information, the look up hash returns something to that effect.