The necessities for compliance with rule 17-a4 include:
• Working with a Designated Third Party consultant (D3P).
• Documented, enforceable retention policies.
• Data that are stored in a searchable index that's easily retrievable and viewable.
• Data that are stored on write once read many (WORM) electronic media.
• Data that are stored off-site.
Ultimately, broker-dealers should have systems in place to store digital content which is protected from tampering and loss.