Explanation
Disaster recovery and business continuity are vital concerns with availability. If data is destroyed or compromised, having regular backup systems in place as well as being able to perform disaster recovery in the event of a major or widespread problem allows operations to continue with an acceptable loss of time and data to management. This also ensures that sensitive data is protected and persisted in the event of the loss or corruption of data systems or physical storage systems.

SOC 2 deals with the CIA triad. SOC 1 is for financial reporting. SOC 3 is only an attestation by the auditor. There is no SOC 4.

Explanation
Cryptographic erasure is a secure method to destroy data by destroying the keys that were used to encrypt it.
This method is universally available for volume storage on IaaS and is also extremely quick. Shredding, degaussing, and demagnetizing are all physically destructive methods that would not be permitted within a cloud environment using shared resources.